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Musings Regarding External Voltage Regulation

Feb 6, 1998
11,264
Canadian Sailcraft 36T Casco Bay, ME
Lately there has been a lot of discussion around external vs. internal voltage regulation so I wanted to pass this info along. I had sent this to another member in an off line conversation a few weeks ago but tweaked it a little for a general posting.

If you want to avoid the diatribe below: In almost all cases an external regulator will yield a better performing charging system, but it may not make "financial sense" for your particular use.

The choice of external vs. internal should ideally be based on:


  • Your use of the boat
  • Your battery bank size
  • Your battery bank chemistry (Flooded, GEL, AGM, TPPL AGM, LiFePO4)
  • How much time you are willing to run the motor each day
DISCLAIMER: I usually try and stay away from this topic because many boaters don't fully understand how alternators, voltage regulators and batteries work and work together in concert. Once the money has been spent, they passionately believe their expensive system is working for them. Sadly about 85% or more of the alternator upgrades we see are incorrectly installed & set up. In many cases the system can be better than what they had, but with a proper installation, could be even better. Some owners however don't step back and make well educated decisions based on use and actual data points and can occasionally spend more money than they needed to. I will try to explain this subject as simply as I can.

I am making a LOT of general assumptions below so be patient:

1-
Voltage is the pressure that cause the batteries to accept current.

2 - Amps are the "flow" and the higher the pressure/volts the more the flow/current can be.

3 - The alternator is not "forcing" or dictating amps to a battery, it does not do this, the battery "accepts" or lets current flow, based on voltage at the battery terminals and SoC.

4 -The alternator provides the current up to what it can provide or the battery can accept at XX.XX volts. Prior to the battery reaching the absorption voltage the alternator is basically *full throttle providing all the current it possibly can.

*Unless the regulator uses a temp gradient type regulator.

5 - A voltage regulator is little more than a VOLTAGE LIMITER. All it really does is LIMIT or maintain a preset voltage once the battery bank gets to the target voltage. External high performance regulators can limit voltage based on battery temp, alternator temp, time at voltage & other parameters but they still limit voltage.

Temperature compensation of the alternator and batteries is one of the most useful features of external smart regulators. Voltage limiting or voltage regulation modifies the alternators field voltage/current to maintain the desired set point voltage. This regulation technique is called pulse width modulation. Simply put the on time and off times are modulated at insane speeds in order to maintain the desired voltage set point the regulator wants to see or is limiting voltage to.

If the voltage starts to creep up the PWM or off time to the alternator field gets extended. Cutting back the alternators field limits the current the alternator can produce and thus a voltage limit is maintained and voltage over-shoot is prevented. Good quality external PWM regulators can control voltage to within a 10mV to 30mV range or 0.01V to 0.03V.

If you add a big load the regulator will boost the fields on time to maintain the voltage set point. PWM all happens so fast that you'd need an Oscilloscope to even begin to see it. If the load exceeds what the alternator can produce, eg: a bow thruster, the regulator reverts to full field or 100% output. Voltage limiting and PWM modulation of the field voltage/current go hand in hand.

6 - A typical voltage regulator has no clue what the amperage is coming our of the alternator. All the regulator knows is voltage, hence the term voltage regulator. Voltage regulators regulate based on voltage not amperage. While the amperage out of the alternator changes up & down to maintain a voltage set point the regulator is doing all of this all based on voltage.

7 - The internal resistance of a battery determines the current it "accepts" or takes from the alternator to maintain a voltage at a specific state of charge.

With a small alternator, in bulk mode, the alternator will be limited to what it can physically produce, while hot. What it can produce is based on RPM and alternator winding temperature. Bulk just means "full field" or that the alternator voltage sense circuits has still not attained the pre-set voltage limit of the regulator. This stage of charging is called BULK or constant current (CC). In Europe, under DIN standards, they often call bulk charge a BOOST.

The relation ship of alternator current to banks size also plays a role. A small alternator attains the CV stage voltage limit at a higher SOC. Conversely, if you have a very large amperage alternator, the bulk period will be shorter and the battery bank will attain the voltage limit (CV stage) at a lower overall SOC. With a large source of current a battery can come up to absorption voltage more quickly because the battery can not accept the current, into the battery plates, as fast as the source can provide it. This builds a surface charge on the plates and results in driving the voltage up faster than a smaller current source.

8 - Let's address charging lingo such as *Bulk, *Absorption & Float.

FACT: Both smart and dumb regulators do both bulk (CC) and absorption (CV) or CC/constant current & CV/constant voltage stages.

BULK / CC - Bulk charging is essentially FULL FIELDING the alternator in both smart and dumb regulators. Bulk charging is any period of time before the regulator has attained it's absorption voltage limit at the battery terminal, or alternator, if "voltage sensed" there. In the bulk stage the alternator is delivering the maximum current it that it can based on temperature and rotor RPM.

As a battery charges during bulk its terminal voltage gradually rises. If the regulator, smart or dumb, has been set to 14.4v then until the batteries hit 14.4v is considered bulk charging. Bulk charging is also called constant current charging meaning the charge source, in this case an alternator, is supply all the current that it physically can at its current temperature and RPM.. Bulk is where the maximum current will flow into the battery because the batteries internal resistance is low due to being discharged.

During bulk charging the differential in pressure or voltage is at its greatest and thus the battery is accepting all the current the alternator can feed it as the terminal voltage slowly rises.

ABSORPTION / CV - Once the battery attains the voltage limit the regulator switches from the bulk/constant current stage to the absorption/constant voltage stage and begins regulating to the voltage limit.

Once the voltage is held steady or voltage limited the current being accepted by the battery begins to decrease. This is because the regulator is now operating in CV or constant voltage mode and as SOC rises the battery needs or accepts less and less current in order to maintain & not over shoot the voltage limit.


FLOAT/CV - Float voltage is a further reduced constant voltage limit applied by a smart regulator. Dumb regulators do not do a true float. If you feel you need float, because you motor a lot more than you sail, you's want a smart external regulator.

All of the above is based on what I have seen, read or heard most people misconstrue. You may not have misconstrued any of it but it is good to get out there.



Marketing Mumbo Jumbo: Just because companies such as Balmar call "bulk" (BV) a voltage limited stage of charging, the simple answer is that this is not true. Charge product manufacturers that do this, and we are a large Balmar dealer, are simply using incorrect terminology. Some companies do this purposely to confuse & confound the customer into thinking they are getting more. In teh case of Balmar the EE who designed the regulator used three CV stages and one CC stage. He called the first CV stage BV or Bulk Voltage, the second stage AV or Absorption Voltage and the third FV or Float Voltage. Seeing as Balmar was the first to have two absorption level voltages this seemed to make sense.

Of course, this is really all just marketing and we live with it every day. Bulk charging is constant current or when related to an alternator constant potential based on heat and rotor RPM. Bulk is simply not a constant voltage stage. In recent years more and more companies have begun using the incorrect terminology of "bulk voltage". You can have a bulk transition voltage, the point at which it transitions to absorption, but you can't really have bulk voltage that is constant voltage.

During bulk charging the battery voltage is ALWAYS on the RISE thus it can not be a "bulk constant voltage".. More appropriate terminology, as related to products such as the Balmar regulators might be Absorption 1 & Absorption 2.

As mentioned above I know why the designer of the Balmar regulators named it bulk voltage. I had long conversations with Michael, including discussions specifically about terminology, and he admitted it was an incorrect use of terminology that just got adopted by the marketing department. Of course, at the time, with a regulator that had 15,000 lines of code, correct industry accepted and defined terminology was far from the first thing on his mind.


  • Bulk = Constant Constant or Constant Potential Charging
  • Absorption = Constant Voltage Charging
  • Float and Equalization = Constant Voltage Charging
Charge Rate vs. SOC vs. Absorption Transition:
At the bulk to absorption transition voltage the regulator begins voltage & current PWM mode in order to maintain the pre-set voltage limit. With an adequately sized alternator this is often stated & repeated as a state of charge (SOC) of somewhere around 80% SOC. This however is not always a truism.

The SOC at which you attain absorption voltage is entirely dependent upon how much charging current you have. With a small solar array, you may not hit absorption voltage until 96% SOC and with a massive alternator you may hit absorption at 65% SOC. The point at which your battery bank attains the voltage limit is entirely depending upon how much current you have available. On top of current availability sulfation, battery state of health and *incorrect voltage sensing, among others, will change the point at which the battery attains the CV/voltage limit.

*Accurate voltage sensing is critically important on sailboats that desire short engine run times. Factory alternators do a horrible job with this. For more in-depth discussion on this subject see: Alternators and Voltage Sensing Why It's Important


Sulfation & SOH Impact Bulk Charge Time:

A sulfated battery or a battery in poor state of health (SOH)will quickly rise to absorption voltage despite not yet actually being charged. Simply put until a battery reaches the voltage limiting set point, absorption charging, all regulators, smart or dumb, simply "*full field" the alternator to what ever the regulator can produce in field voltage/ field current. Battery chargers and solar controllers operate the same way.

If your battery bank starts out at 50% SOC and you;re attaining the voltage limit in a short period of time the battery is likely shot. At a charge rate of .2C, or 20% of Ah capacity in charge current, it should take an hour or more to attain the absorption voltage limit.

*The exception is an alternator with a thermistor/temp gradient regulator.

Can Internal "Dumb" Regulators Really Do Bulk Charging?

Yes they absolutely can, though there are certain things that can impact just how well they do this compared to an external regulator.

The question below was posed on an external alternator regulator manufacturers web site. This company builds smart external regulators and alternators.

Question:
As I understand it most of the regulators regulate voltage not amperage? Before the regulator hits the absorption set point, mine is 14.4 volts, they are simply full fielding the alternator. So do both dumb and smart regulators do the same to the alternator, apply full field until the absorption voltage is reached?

Answer from Manufacturer:
You're correct, during the bulk phase, the alternator is 'full fielded', by all regulators. But the term 'full fielded' is loosely defined as applying the maximum voltage that can be applied by the regulator. If you measure the voltage drop between B+ and field during the bulk cycle you'll find that an XXXXX Regulator drops the least voltage of any regulator. More voltage on the field means more Amps.

While the external regulator can produce a higher field potential, is this always necessary? The answer is no, it is not always necessary. We should consider that an external regulator must be able to drive any alternator it is fitted to, and it will need the capability to deliver a wider range of field potential to any alternator out there. External regulators can deliver upwards of 15A to drive the field. An internal "dumb regulator" only needs to produce enough field potential to drive the specific alternator it was designed to be fitted on in order to attain its maximum output rating. For some alternators this may require as little as 4A. There is no reason for Delco, Bosch, Paris Rhone, Leece-Neville etc. to design an internal regulator capable of 15A when the alternator is only needing 4A to attain its full output. In industry pennies count. A general fit external regulator must be able to drive any alternator so they are built to do this. While the statement above is technically true it is misleading at best.

A few years ago I spent an entire Saturday at a friends shop conducting experiments with many different internal dumb regulated alternators. This shop has a $30,000.00 alternator testing machine I got to play with for hours.. I loaded random internally regulated alternators into the machine and tested them for max alternator rated output.

Bottom Line? Every single internal dumb regulator applied enough field voltage/current to achieve the max rated output of the alternator, every one. Keep in mind however this was "cold testing" and as some alternators heat up they reduce the voltage limit based on internal thermistors. I will get to this later.

While you may be able to apply more field potential, as most external regulators have the ability to, you can't exceed the alternators physical capabilities. If the alternator can hit its maximum output rating with a *dumb regulator, then a smart one, set to the same voltage and sensed at the same spot, will not increase charging times in bulk stage.

*Excludes thermistor equipped/temp gradient internal regulators

This video may help pull some of the above together:

Let's Put This Into Practice:

*If you take two identical 100 amp alternators and two identically discharged battery banks and one smart and one dumb regulator (truly dumb, no thermistor), and they both sense voltage at the same point in the system, they will both charge at the same speed in bulk. No magic here just basic Ohm's law stuff. Full field is full field.

*Assumes everything is the same except the regulators.

The bottom line truth is an *external regulator will not charge faster if the voltages are set equal and the set up and wiring is the same. (*non-thermistor type)

External Regulation Instillation Practices Matter:

The sad reality is that the vast majority of external regulators I see installed are almost always set up to physically charge slower than they can. Due to improper programming and incorrect installation practices they enter float far to early in the charge curve. This robs owners of the charging performance they paid for. The "advanced programming" menu is Balmar regulators is there for a reason! The temps sensors are sold for a reason!

External regulators WILL DEFINITELY charge faster if you set them up correctly using the correct absorption voltage for your batteries. You push absorption voltage higher with an external regulator because you have a float feature after a high absorption voltage. You would not want a high absorption voltage setting, actually the only CV setting, on a "dumb" regulator.

When you dumb it down there is nothing fancy about voltage regulation/voltage limiting or PWM control of the alternators field. Smart regulators do not charge faster, when set at the same voltage set point, and all other things being equal because a battery is only going to accept what it can accept at a specific voltage and SOC.

The battery really has no clue it is hooked up to a $400.00 external regulator or a $15.00 internal regulator, all is knows is the voltage at its terminals and how much current it will accept at that SOC and at that voltage. Course if your internal regualtor is set for 14.6V and you motor down the ICW for 10 hours per day you're going to be adding water to the batteries quite often. If you do this with AGM or GEL the batteries will be getting over charged.

External regulators can be set up to charge faster and to maximize the alternators output. This only works if you set them up properly for your battery type. Sadly many installers or DIY's don't set them up this way. I would estimate that a solid 80% of the external regulators I see are still on the UFP (universal factory program) setting.. This gains you little to no benefit over a *dumb regulator in charging speed.. (*truly dumb no thermistor)

Why Do Internal Regulators Get Such a Bad Rap:

#1 Voltage sensing -
Most internal internal regulators sense voltage at the back of the alternator, not at the battery terminals. The factory wiring between the batteries and alternator can induce substantial voltage drops causing the batteries to charge slow and hit limiting voltage far earlier than they should.

#2 Internal Regulator Temp Gradients - Some dumb regulators are what I often refer to as "Super Dumb". By this I mean the alternator protects itself by reducing the regulation voltage as it heats up. This serves to protect the alternator, smart for the alternator, but super dumb for deep cycle batteries. There are better ways to keep the alternator from running too hot than a thermistor protected regulator.

For a more in-depth look at this subject see here: Automotive Alternators vs. Deep Cycle Batteries

#3 Low Voltage Fixed Limit Point - Some alternators have an absorption voltage set point that is far too low, below 14.4V. Combine this with inaccurate voltage sensing & a temp gradient and you have really, really $hitty charging performance.

Are All "Dumb Regulators" The Same?

No, they are not.

Dumb:
A simple dumb regulator has but one voltage set point and that is it. It can do Bulk/Constant Current or *Constant Potential (*accounts for heat and RPM) and Absorption/Constant Voltage. If this set point is 14.4V you 're going to do okay if you're a weekend sailor with a small bank who ties to dock charging during the week. This also assumes you have minimal voltage drop between the alternator and batteries. If you move to a large bank that spends a long time in bulk these alternators can and do literally burn themselves up. I replace or rebuild approximately 5-15 alternators each year that have physically burned up from spending too much time in bulk and being chronically over-worked.

Super Dumb:
Hitachi/Yanmar, Valeo, Mitsubishi, Bosch & most newer auto-based alternators are dumber than a pound of beetle-crap to install on a boat with a deep-cycling battery bank. To the alternator or car batteries they are pretty smart but to your deep cycle batteries, and the negative impact in relation to actually charging them in a healthy manner, they are flat out stupid.

Why? Hitachi & many other automotive alternators with internal regulators, limit voltage but they also reduce voltage based on alternator temperature. They usually accomplish this using internal thermistors in the voltage regulation circuitry. In a deep cycle application this amounts to a self protective feature to try and prevent the alternator from cooking itself. In automobiles this type of circuitry is a cheap way to minimize the over charging a car battery in a hot engine compartment. Due to often super high automobile engine bay temps this thermistor reduces output voltage to a safer level. On a boat however, the batteries are not in the engine bay, or should not be, so the thermistors heat sensitivity is driven by how hard the alternator is working and the heat generated by the alternator itself from being worked hard in bulk. Remember voltage is the pressure so by reducing the limit voltage, we also reduce the current that can flow into the batteries and chop charging performance dramatically.

On boats battery temp sensing should be done directly at the battery, not inside the alternator. If you want to protect the alternator then reducing the field, not the regulated output voltage, is the proper method with a deep cycling bank. If we reduce the voltage limit, then we also reduce the current the alternator is supplying to the battery. Add in some voltage drop and we now have an 80A alternator only capable of as low as 20-30A in bulk..... The thermistor protection is good for the alternator, and it usually gets the manufacturer through the warranty period, but it is horrible for your deep cycle batteries.

The battery simply will not accept the same current at 13.4V that it did at 14.4V. As a result the alternator will run cooler but the battery will charge at a snails pace. What do you suppose this chronic under charging does to your batteries over time.......?

The behavior is that when cold you will get 14.3V to 14.4V out of the "super dumb" regulator but as the alternator heats up the "super-dumb" regulator begins to reduce the CV/voltage limit based on the alternators internal temperature. It is not uncommon to find a Hitachi alternator at 13.4V when hot. This is really, really, really bad for your deep cycle batteries.

If you have a super dumb regulator, and notice the voltage dropping, or not climbing and current output abysmal,it is likely a thermistor protected dumb regulator.

Super Dumb Rx = Get rid of it or plan to buy new batteries more often. If you have a temp compensated automotive type alternator you are really in dire need of external regulation if deep cycling a larger battery bank. I do not recommend converting these stock alternators, below 80A, to external regulation because the amount of current limiting required to get them to run at a safe temp makes them nearly useless in terms of charging current.

"So if I have a basic dumb regulator at 14.4V, with no thermistor gradient, it can charge at the same speed as an external regulator?"

Yes it potentially can, but ONLY if everything is the same including voltage sensing. This is not what you will hear on the docks especially from owners who have gone from internal to external because they have not done a fair or equal comparison. The caution here is that as you grow your bank size you run a much higher risk of burning out the dumb regulated alternator. On top of that flooded and many AGM batteries need to be charged and higher voltages than 14.4V for optimal service life..


But I am just a weekend sailor?

Many boat owners, when upgrading an alternator system, also upgrade the battery bank and or alternator & wiring at the same time so the performance claims can be misguided & often misunderstood. This is not an equal or a fair comparison to their old alt or bank or an equal baseline measurement from which to draw a fair conclusion.

Thus, the industry marketing works and boat owners believe that an external regulators will always charge their bank faster. Based on how I see them incorrectly set up, this is simply very often not true. While true for some, compared to their old system, this is not always true, in every situation, or with every brand of external regulator. As a weekend sailor with a small bank, starting our from 100% SOC each weekend, and a dumb regulator set at 14.4V, your performance gains may not be worth the cost outlay to go to external regulation.


Fair Comparisons:

This graph below was done by Practical Sailor and illustrates the point of 14.4V is 14.4V or voltage is voltage rather well. Unfortunately there were a few flaws in their testing methodolgy.

The most glaring issue is that they compared a "dumb" regulator set to 13.8V to smart regulators set to 14.4V. This is NOT a fair comparison, or even very representative of today's stock alternators which almost always have higher voltage set points. This was a flawed testing protocol on the part of Practical Sailor.

Where the graph diverges, between dumb & smart, is when the batteries hit 13.8V volts. If the dumb reg had been set to 14.4V the graphs would be virtually identical all the way up. I've repeated this on my own bench and on my own boat.

I have used, installed and owned external regulators made by Sterling Power, Balmar, Heart Interface, Xantrex, Mastervolt and Ample Power. With a small flooded bank there is no reason a weekend sailor can't tough it out with a stock alternator. This is even true of "super dumb" regulators depending upon use. See, we keep rounding back to that word again, USE. How you use the boat, what type of batteries you have, average depth of discharge, and the size of the bank is how to best to attack alternator charging..

There's no secret sauce, voltage/pressure limits are voltage/pressure limits. There is lots of tremendous & very useful "secret sauce" features in an external performance regulator but 14.4V is 14.4V to the batteries no matter where it comes from.

The article this graph comes from is one reason why PS sometimes gets a bad rap for "less than in-depth" and a "less than fair" analysis. I am not pricking on PS here, I am actually a contributor/tester/writer for them, but you can't compare two UNEQUAL VOLTAGES and then claim "external regulators charge faster". Yep no kidding a pen, paper and Ohm's law tells us this.. There are a number of marine alternators out there, the Motorola/Prestolite/Leece-Neville 8MR series to name one, with simple 14.4V dumb regulators. As a point of reference I have not seen a 13.8 volt regulator on a newer engine in the last 18 + years.

A comparison like this is only good for those with antique alternators limited to 13.8 volts, of which there are still many out there. Mistakenly PS, for that article, chose an antiquated 13.8V model to compare to 14.4V. A fair or equal comparison...? No, not at all.

PS Graph



Misleading Marketing??

Some of the regulator manufacturers can be rather unscrupulous when it comes to "charge faster" claims. Some of them are comparing their product to old style regulators that used to have voltage target set points of 13.6 to 13.8 volts. Almost all new marine alternators come through at somewhere between 14.2 - 14.6V and have been shipping that way for the better part of 15-20 years. We should ask our selves why the regulator manufacturers have not published head to head comparisons between their product and dumb regulators that are monitored by an independent lab? Where are these white papers? Where is the science and data behind all the secret sauce? Don't hold your breath, we will NEVER see this, because as I said 14.4V is 14.4V is 14.4V no matter the voltage limiting source.

Many manufacturers also make claims like; "you can never achieve a full charge without external regulation". Well, in the pure sense of a sailboat, then yes. With a regulator set at 13.6V it will never fully charge the bank on the diminutive hours spent running the motor, but neither do smart regulators, when looking at average engine run times in sailboats.

Some external regulator manufacturers are more unscrupulous than others. One UK manufacturer is rather over the top in this regard. They have chosen voltage settings exceeding 15V, compared to 13.8V, in order to compare charging speed. Obviously a higher voltage / pressure will absolutely cause the bank to charge faster, but, again this is an unfair comparison to many of today's voltage set points. The battery can only take what it can take once it hits target voltage so we can't charge to full in teh time periods they are suggestion you can.

I love external regulation and stand behind it 150%, for the right application. I install a lot of external regulators and high performance alternators, when it is wise to do so. I am only urging you to do some leg work and figure out what you really need.

Boat Use Determines Charging System Needs:

Weekender / Day Sailor -
Unfortunately a day sailor or weekender who does 40 motor hours per year on two group 27 batteries, who ties to a dock with shore charging after each weekend or day sail, is very often making a marketing based financial decision to spend $1000.00 +/- on a performance charging system, yet I see it all the time. Many times the performance charging system yields a poor financial to actual gain. It sure doesn't hurt anything to upgrade, except for your wallet.

Cruiser - A cruiser who spends lots of time away from the dock, deeply cycling the batteries, would be very wise to make a move to a higher performance charging system utilizing external regulation.

Mooring Sailed Vessel - A mooring sailed boat can almost always benefit from an alternator & regulator upgrade. First however, the owner should consider solar.

What's The Big Difference In A Few Volts ???:

The difference between 13.6V & 14.6V does not seem like much but it is a BIG difference in terms of "flow" of current into the battery. At 13.8V a battery can often plateau and hit absorption at about 60-65%+/- SOC, depending upon age, the current source and condition of the battery, and will charge quite slowly beyond the absorption voltage if it is held low. In contrast the battery will charge faster the higher the voltage is set, but it should not be set not too high. For typical flooded lead acid batteries 14.4V to 14.8V is what is recommended by most battery makers. 14.9Vcan even be a short duration bump, not constant, and this can be done with an external regulator such as a Balmar.

For example you may set the BV voltage to 14.9V for 18 minutes than set the AV voltage to 14.8V for the duration. You could also set BV to 14.8V then AV to 14.7V. By setting the first target voltage a bit higher you get to a higher SOC faster. An internal regulator can't do this.

When talking about voltage differentials we need to consider that current will not even begin to flow into a battery until a voltage slightly above its resting voltage. So if your battery was at 12.4 volts and you flipped on the charger real current would not even begin to flow until above 12.4 volts. Consider about 0.1V above resting open circuit volts as the flow threshold where current begins flowing.

If you now compare a 13.6 volt limit to a 14.8V limit that is a HUGE percentage increase in charging pressure. Remember, in the above scenario the base line was at 12.4V volts not 0 volts. This difference in voltage is how external regulator companies began to make their "charge faster" claims. Remember, we are not starting at a baseline of 0 volts, we start this at about 0.1V higher than resting open circuit voltage. So, the difference in charge speed between 13.6V & 14.8V is actually quite dramatic. Comparing a regulator set to 13.6V to one set to 14.6V is like pitting Bode Miller against Janet Reno is a ski race, no comparison.

Note: If you have noticed over the last few years companies like Balmar are no longer focusing on "charge faster" claims and are focusing on the many other great features their regulators offer. They simply moved away from being a company that does quasi misleading marketing to one of feature/benefit selling. This is good news because the Balmar regulators have lots of tremendous benefits beyond the "charge faster" claims made early on.

"What Should I Do?"

Dumb Regulator Low Voltage -
If you have an old 13.6V - 13.8V regulator, and wet cells, ditch it and get a regulator that is a minimum of 14.2V - 14.4V or even 14.6V and you will charge a lot faster. If you choose a different internal regulator, this is often an option, keep in mind that battery gassing generally begins above 14.3V. Of course the gassing voltage is temperature dependent, so a dumb regulator that does 14.5V - 14.6V will cause your flooded batteries to need water added more often. While 14.4V would be easier, maintenance wise, an absorption voltage of 14.6V - 14.8V will both charge even faster and is going to fend of sulfation better and be healthier for the flooded batteries.. If you are a coastal cruiser doing 40 engine hours per year, a new internal regulator (not a thermistor model) is an adequate compromise option. The best case here is to convert to external regulation if your alternator is large enough to make good use of it..

Dumb Regulator Set to +/- 14.4V - This can work adequately well provided you have minimal voltage drop in the system and it regulates to around 14.4V or so. While a single voltage regulator is less than ideal, especially, if you are not a full time cruiser, an arrangement like this can work adequately well for weekend boater.. Be aware that with a large bank you can literally burn up a dumb regulated alternator because it has no temperature protection circuitry.

Super Dumb Regulator - (temp compensated) If you tie to a dock after each sail and shore charge the bank, you can usually just keep this alternator. If you actually cruise, & deeply cycle the batteries, do yourself a favor and get rid of it.

Voltage Sensing Improvements: Many stock alternators can be set up or wired to provide external voltage sensing at the battery terminals as opposed to the back of the alternator itself..

Please do not try this if you don't know what you are doing. Any good alternator shop can help you wit this and it can make a big difference in charging performance. The only good way to get accurate voltage sensing is for the negative regulator lead and the positive sense lead to be direct wired to the battery bank.Voltage sensing is a circuit just like any other DC circuit. Moving only the positive sense only corrects for the positive side of the circuits voltage drop.

How Would I Measure The Voltage Set Point Of My Existing Regulator:

With the batteries at 100% state of charge run the engine and test the voltage output at the B+/Output terminal of your alternator with the DVM neg lead to the case or neg terminal of the alternator. The voltage should be somewhere between 14.2V & 14.4V but I would not go much above above 14.6V with a "dumb" regulator. Many regulators on Universal engines were factory set at 15.0V to try and compensate for the ammeter & horrible factory wiring.

Is Float Necessary On Sailboats?

In my opinion, mostly no. Emphasis on mostly.. Float for many sailboats is a tool best left to the trawler crowd who actually run their engines day in, day out for hours and hours on end. It is also a good option for those who choose expensive AGM or GEL batteries with higher acceptance rates getting you to "float" faster than wets will allow. If you plan however on doing the ditch it is a very good feature.

For the amount of time you, a sailor, are charging off an alternator, and the potential amount of hours spent at 13.2V - 13.6V float levels being so VERY, VERY limited, it may not be necessary for your boat to even have float for the alternator.. Unless your batteries have high acceptance rates, you motor for long periods or you also have an alternator that can deliver lots of amperage don't consider this a hugely critical requirement..Float is rarely going to be useful to you unless you are really a trawler with a stick. One of the problems with float and external regulators is one I call "premature floatulation". Owners and many techs rarely set up external regulators correctly and they drop to a float voltage far too soon, just as the lawyers want it to. As I mentioned earlier the "advanced programming" menue is in the Balmar regulators for a reason. Use it!

For solar controllers, or shore chargers float absolutely necessary. Float is a great a feature but less critical for alternator run times we often have on boats. Again, your use will determine if you need a float feature for your alternator.

"Did I over-think my system?"

In my opinion a a fair amount of coastal sailors/weekend boaters, with cheap flooded batteries, can over-think an alternator charging system.

With certain battery types though you really do need to address the system. The reality for me is that I see approx about 20% of the boats out there that have AGM, GEL or AGM TPPL batteries, yet a large portion of the weekend use boaters have an upgraded alternator charging systems. Many of them with no dire need. Money wasted? Some times yes, when based on actual use..

When Should I Use External Regulation?

Flooded Cell Batteries -
If the bank exceeds the hot rated alternator capacity by more than 80% I recommend a smart regulator, temp sensing of both battery and alt and belt/amp manager. Eg; a 400 Ah bank can accept about 100 amps in bulk so a 70 amp alternator, using its hot rating, would get external regulation with alternator temp sensing at the least.

TIP: I generally install a larger amperage alternator than is desired for the design output. I then de-rate or limit the output of the alternator within the regulators settings. This allows the alternator to work less hard, run cooler, live a long happy life and be at much less risk of failing. De-rating the output of the alternator can be done with Balmar regulators. If I am sending a customer off shore it's a very rare case where I am allowing the alternator to be driven to 100% output by the regulator.

AGM- I always recommend external regulation with alternator and battery temp sensing at a minimum. I have seen a number of dumb regulated alternators burned down by the high acceptance rates of AGM batteries. Temp sensing of the batteries is a requirement for these expensive batteries.

GEL- I always use external regulation with alternator and battery temp sensing at a minimum. GEL's require specific voltage ranges that dumb regulators just can't accommodate very often. Battery temp sensing is a must with gels IMHO.

TPPL AGM's - Same as AGM

Dumb Regulator / Temp Compensated (Hitachi/Yanmar etc.) - These alternator regulators are horrible for deep cycling applications. IMHO nearly every Yanmar engine with a Hitachi alternator, if used regularly in a deep cycling application, should have it converted to external regulation or convert to a new alt & regulator.

Dumb Regulator / Low Voltage Set Point - If your alternator regulator is set to less than 14.2V it would be wise to invest in a better regulator.

Inaccurate Voltage Sensing - This piece can not be over looked. Many factory systems have horrendous voltage drop between the battery bank and alternator. These alternators are also "self sensed" meaning they measure system voltage at the alternator BEFORE ANY VOLTAGE DROP.... This can cause the alternator to go into CV / voltage limiting mode prematurely. External regulators correct for this by allowing positive and negative regulator wires (volt sensing) to be routed directly to the battery terminals. This can yield significant charging performance increases..

Summary:

In short, smart regulators most definitely do have a place on cruising sailboats & they are tremendous tools. However the use should ideally be well justified for the expense laid out. The installation of a smart regulator should be considered in the total system design. Their use is very often justifiable, but occasionally it's not, especially for a weekend use coastal cruiser.

The average small bank of flooded batteries, for a weekend cruiser, does not absolutely require a $1500.00 + charging system when a simple regulator, with the proper voltage setting, will work suitably well. In my experience a good battery monitor, properly programmed, or another way to monitor SOC performance, such as the Balmar Smart Gauge, should be the first place to start your upgrading. If the SOC is telling you you're not meeting charging performance you desire then by all means address it.

Hope this was a somewhat helpful topic on alternator regulation.

P.S. I love this quote from Balmar:D

Quote From Balmar:
"Forget the rumor that an oversized alternator will destroy your batteries ... the truth is that the acceptance rate of your batteries will dictate how much amperage the alternator will provide."
 
Aug 16, 2009
1,000
Hunter 1986 H31 California Yacht Marina, Chula Vista, CA
For those of us about as dumb as our regulators, I would like to thank you for a very helpful post, Main. I have 3 AGM group 31 batts, and the stock 35 amp Hitachi that came with the Yanmar 2GM. I have refrigeration, may install radar, and a microwave aboard. Conversion is handled by my old Xantrex 2000 and we are on shore power unless we are out of the slip. No solar or wind. I like to run the engine at least 3 hours a month going up the channel to the SD Bay just to keep the diesel happy and the antifreeze circulating. If we do any coastal sailing, there is another 3 or so hours or motoring. Do you feel I should consider a slightly larger alternator, maybe 65 amp with smart regulation? If so, what regulator would you recommend, or at least what specs should I look for?
 
Feb 6, 1998
11,264
Canadian Sailcraft 36T Casco Bay, ME
For those of us about as dumb as our regulators, I would like to thank you for a very helpful post, Main. I have 3 AGM group 31 batts, and the stock 35 amp Hitachi that came with the Yanmar 2GM. I have refrigeration, may install radar, and a microwave aboard. Conversion is handled by my old Xantrex 2000 and we are on shore power unless we are out of the slip. No solar or wind. I like to run the engine at least 3 hours a month going up the channel to the SD Bay just to keep the diesel happy and the antifreeze circulating. If we do any coastal sailing, there is another 3 or so hours or motoring. Do you feel I should consider a slightly larger alternator, maybe 65 amp with smart regulation? If so, what regulator would you recommend, or at least what specs should I look for?
Wufi,

The risk you have is when you deplete your AGM bank, not when leaving the dock with a full charge. AGM's can take up to 100% or more of their 20 hour Ah rating in charge current, Lifeline claims 500 amps in-rush for a 100 amp battery and I have seen these batts take a full 85% for more than just a short duration.

Wet cells will accept roughly 20-25% of the Ah rating. So a 100 Ah battery in wet cell technology would take just 25 amps charge current and a Lifeline AGM of 100 Ah's could take 85+ amps.

Dumb regulators are just that dumb, meaning they don't normally have any sort of temperature limiting feature built into them, just voltage limiting. this is fine for moderately sized wet cell banks but when you go Gel or AGM external regulation should strongly be considered. Because of this 'dumbness";) a small alt without temp regulation can be over taxed and asked for the full output for hours on end until the bank starts backing off the acceptance. If this happens you can very easily melt your alt down especially in the confines of a hot & small engien room on a sail boat. I have seen this repeated many times. Essentially the alt gets so hot that the coating on the windings melts off and the alt is fried.

With AGM batts I would strongly suggest the use of external regulation WITH temp sensing of at least the alternator. Balmar, Xantrex, Sterling and Ample Power all make good units.

This was an alt that lasted nearly 18 years on wet cells but burned down twice in two months with AGM batts due to over heating. These windings should be copper colored with a clear coating not scorched.
 
Sep 29, 2008
1,799
Catalina 310 #185 Quantico
Sort of an off topic question

MS, What would you recommend to measure amps over time to compare performance of a wind turbine to actual wind velocity. I am looking for an ammeter that records current with a time stamp that can be downloaded to a computer and analyzed.
 

CalebD

.
Jun 27, 2006
1,479
Tartan 27' 1967 Nyack, NY
Excellent discourse.
Have you posted this on any of the other forums you sometimes visit? I wish you would. If not, maybe you should consider adding this to your Compass Marine Projects page so some of us could link to it.

Wufi,
I could not find any alternators in the SBO store but Moyer Marine sells 2 different alts (55A and 120A) that work with the Atomic 4. Not sure how or if they would work with your 2GM though: http://www.moyermarine.com/cgi-bin/shopper.cgi?search=action&category=OVEL&keywords=all&template=Templates/B000_storebuilder.html
 
Feb 6, 1998
11,264
Canadian Sailcraft 36T Casco Bay, ME
Excellent discourse.
Have you posted this on any of the other forums you sometimes visit? I wish you would. If not, maybe you should consider adding this to your Compass Marine Projects page so some of us could link to it.
Without photos it is tough to post this on my PBase site as that is a photo based site with photo/blog capabilities. Text is an after thought there and paragraphs don't work well hence all the ***** at the beginning of a new paragraph. I have not yet had a chance to post this elsewhere but I'm sure when I get time I will.

Here's a direct link to the post: http://forums.sbo.sailboatowners.com/showpost.php?p=775433&postcount=1


If you want to link directly to any post in a thread simply click the PERMALINK word of the individual post in a thread and that will be your direct link to copy & paste.

See here's your "PERMALINK" post: http://forums.sbo.sailboatowners.com/showthread.php?t=125392&#post775469
 

Bob S

.
Sep 27, 2007
1,558
Beneteau 393 New Bedford, MA
A timely post

I had a problem with my electrical system and I'm not sure why. Leaving an anchorage heading home my chartplotter screen went haywire. I was pretty upset remembering a post about someone loosing a C70 screen. We motor-sailed for maybe 20 minutes when my wife said something didn't sound right. I gave her the helm and went below and saw the alternator pulley wobbling. I killed the engine and thought we bent the alternator shaft. If you remember my post about your (Electromaax) serpentine pulley. I machined my own and love how it performed up until now. I even got a comment from my wife "did you do something to the engine it seems much quieter this year".

I removed the alternator I found the split lock washer that held the pulley on broke and the ID of the aluminum sheave stripped out which is hard to figure as it was machined with a better than .001 fit and had a 1/8" key in it. What I think went wrong was I used a pneumatic gun used to mount tires to install the sheave. I probably over torque it breaking the washer. Being loose caused the sheave to strip.

I repaired it by boring it out and making a steel bushing which will be much stronger. When I reinstalled the alternator I found my Balmar Max Charge regulator not working? I checked all the fuses and they were OK. Did i mention the C70 screen came back on when we shut the engine down. I'm starting to believe we were putting out too high a voltage which made the chartplotter go nuts. I'm still baffled. Defender is getting $339 for a new Balmar but I will be putting the dumb regulator back on.

I've been following SBO's electrical advise since I bought my boat (2007) with no previous experience. There's been an evolution in opinions. I did your Leece Neville 90A upgrade and followed your excellent pictorial on wiring for an external regulator. Now I'll be putting the original dumb regulator back. You saved me a few bucks!

The positive!
I gained a bit of confidence in myself through this. I managed to sail the 25kt miles home through Quicks Hole right up to our mooring with no engine :D . I'm not sure I'd have attempted this with a healthy engine.
 
Feb 20, 2011
7,409
Island Packet 35 Tucson, AZ/San Carlos, MX
snip-

The positive!
I gained a bit of confidence in myself through this. I managed to sail the 25kt miles home through Quicks Hole right up to our mooring with no engine :D . I'm not sure I'd have attempted this with a healthy engine.
Nice!

How far? Nautical miles?
 
Last edited:

Bob S

.
Sep 27, 2007
1,558
Beneteau 393 New Bedford, MA
Nautical miles. Funny thing, a few years ago we lost our fuel pump and rode our bikes across Martha's Vineyard to a local NAPA to pick up a fuel pump without knowing if it would work because my wife was too afraid of sailing home. We didn't have much of a choice and she gained confidence in OUR abilities.

On a side note, the Balmar Regulator was fine. We blew the fuse between the alternator and our house bank. Everything seems fine and ran flawlessly in a 10 hour trip home last Friday with no wind.
 
Feb 10, 2004
204
Hunter 426 Rock Hall, MD
Main Sail; a while back I took your advice and installed the Victron 600 battery monitor and it is a nice addition. However, I am having a problem with my engine charging system. Yesterday we overnighted on the hook. When I fired up the Yanmar 4JH3E I found that the house bank, which was down about 25%, was not charging while the start battery was 14+!! Previously I had changed out a faulty solenoid which is apparently wired to the starting circuit. In order to keep the batteries up I switched the battery leads to the solenoid and curiously found that both banks were charging, though not at the level I would expect (13.3). An hour later the house bank showed 12.7 – engine rpm’s made no difference.

Back at the slip, at idle and out of gear the charging went up to 13.1. I shut down the Yanmar and fired up the Fischer Panda which charges the batteries through the battery charger. It showed 13.7 into the house bank, with the same result after shutting down the genset and plugging into the shore power.

I read an earlier post from you about an automatic voltage sensing relay. Do you feel that the solenoid is the problem or is something possibly causing the solenoid to malfunction?
The boat is a 2003 Hunter 426 with a house bank of 450 amps-an 8D and a 4D, a group 27 start battery, and a separate group 27 thruster battery charging off the engine only. All batteries are AGM’s. The alternator is less than a year old Balmar with smart regulator. The batteries are wired to two separate “on/off” switches. Any suggestions will be very helpful.
 
Feb 6, 1998
11,264
Canadian Sailcraft 36T Casco Bay, ME
Main Sail; a while back I took your advice and installed the Victron 600 battery monitor and it is a nice addition. However, I am having a problem with my engine charging system. Yesterday we overnighted on the hook. When I fired up the Yanmar 4JH3E I found that the house bank, which was down about 25%, was not charging while the start battery was 14+!! Previously I had changed out a faulty solenoid which is apparently wired to the starting circuit. In order to keep the batteries up I switched the battery leads to the solenoid and curiously found that both banks were charging, though not at the level I would expect (13.3). An hour later the house bank showed 12.7 – engine rpm’s made no difference.

Back at the slip, at idle and out of gear the charging went up to 13.1. I shut down the Yanmar and fired up the Fischer Panda which charges the batteries through the battery charger. It showed 13.7 into the house bank, with the same result after shutting down the genset and plugging into the shore power.

I read an earlier post from you about an automatic voltage sensing relay. Do you feel that the solenoid is the problem or is something possibly causing the solenoid to malfunction?
The boat is a 2003 Hunter 426 with a house bank of 450 amps-an 8D and a 4D, a group 27 start battery, and a separate group 27 thruster battery charging off the engine only. All batteries are AGM’s. The alternator is less than a year old Balmar with smart regulator. The batteries are wired to two separate “on/off” switches. Any suggestions will be very helpful.
Pat,

I am not a big fan of the Hunter "solenoid combiner". Without seeing your schematic it is tough to comment. I will however give you how I normally address these issues.

#1 Alternator direct wired to house bank with proper fusing within 7" of battery bank. I also add an engine room located "service disconnect switch" so folks working on the engine can kill power to the alt.

#2 New alternator + & - wires of sufficiently size to have less than 2% voltage drop.

#3 Blue Sea ACR or Sterling Pro-Latch R relay to replace factory solenoid. Alternatively a Xantrex Echo Charger or Balmar Duo Charge can also charge the start battery.
 
Feb 10, 2004
204
Hunter 426 Rock Hall, MD
Thanks MS. #1) I have not considered direct wiring alternator to house bank. Will investigate further. I am installing a disconnect switch. #2) Alternator + & - wires being addressed. 3) I will be installing the automatic voltage sensing relay.

I read your posting about the solenoid combiner used by Hunter, which is what prompted me to contact you. Interestingly, an inquiry to Hunter Marine (Marlow-Hunter) tech recommends the Automatic Voltage Sensing Relay. Their recommendation leads me to believe that the problem is somewhat common.
 
Feb 6, 1998
11,264
Canadian Sailcraft 36T Casco Bay, ME
Interestingly, an inquiry to Hunter Marine (Marlow-Hunter) tech recommends the Automatic Voltage Sensing Relay. Their recommendation leads me to believe that the problem is somewhat common.
It is quite common...
 
Mar 13, 2014
1
Four Winns 328 Oakville
First - this site has a lot of great information and I've learned a lot, thanks for that.

Second - Please forgive me if a power boater posting here offends anyone :). I tried to buy a sailboat but my wife wouldn't have any part in it. To compensate, I sail with a friend of mine on his Tanzer 26.

Okay - to my questions regarding charging. I'm getting our boat, a Four Winns 328 ready for cruising this summer and will be adding a 450 Ah house battery bank along with an inverter. I currently have a 40A 3 stage charger and understand I will need to upgrade it to properly charge the new bank in a reasonable time; Xantrex suggested a 60A charger. We'll be out for a couple of weeks without shore power this summer so I expect the battery charge to be a mix of alternator while we are cruising (twin engine, so 2x 65A Mando alternators) and possibly generator (4kW), only if required.
Basic alternator charging plan looks like this (from BlueSeas, I have inboards):

Currently my generator starts off the house bank, I'll need to think about that.

My understanding if I read the above correctly:
1. There is no way to apply too much current to a battery. It simply accepts a certain amount of current if the charging device can provide it, but effectively self limits the amount of current it will accept.
2. It is possible to charge with too high a voltage, which can cause gassing and extra maintenance.

Questions:
1. I was worried that charging with both alternators at once, so a max of 130A might be too much, but now I'm starting to think it's okay (#1 above).
2. If the alternators can safely charge with 130A, why do I read and why is Xantrex telling me to use a 60A charger? Could I not use a 100A charger safely and provide more current, and charge faster? From what I've read it would be self limited by the battery.

I'm sure I'll have more, if you guys are willing to offer advice,

Steve.
 

dLj

.
Mar 23, 2017
1,161
Hunter 30 Snug Harbor, Lake Champlain
This is a very informative write-up. There is only one thing missing that I would really like to hear about: equalization. You talked about the other stages of battery charging and touched on sulfation, but you didn't talk about equalization. Many years ago, I spent some time on a sailboat that was owned by an electrical engineer that had worked at Hoover Dam. He and his wife were at that time retired and living on their sailboat. He told me about equalization and how it breaks down sulfation products in the battery. Not that it's perfect, but it certainly helps extend battery life. Ever since learning about this, I have performed it on all my boat batteries and my car batteries since then. I typically get between 15 and 20 years of life out of my batteries quite consistently. Your mileage may vary...

I don't think it works on anything other than flooded lead acid batteries.

West Marine now has a short blurb on their website, but I find it limited in scope.

https://www.westmarine.com/WestAdvisor/Selecting-a-Battery-Charger

West Marine publishes the voltage range of 15.5 to 16.2 volts for equalization but my (often faulty) memory seems to have 15.8 to 16.2 volts as the appropriate range. I am using an old (1970's) Lambda programmable ( both voltage and current) power supply to run my equalization cycles as I can program that power supply controlling voltage to within about 0.05 volts. I have no idea how precise the current output runs, but I image pretty tight. I don't have to worry about the current side as the maximum output of this particular power supply is 1.3 amps. I wish it would go to 2.5 amps, but I can't afford a power supply of this precision today, so I just deal with fairly long equalization cycles. I tend to take somewhere around 18 hours to produce a fully equalized battery at this output level. It does depend upon how badly the battery needs to be equalized and the size of the battery.

I do not know what the maximum current should be, but I seem to recall somewhere in the range of 2.5 amps, but the real constraint is that the battery can not heat up during this process. I don't know what kind of time periods would allow complete equalization if the current were to be increased above my limited 1.3 amps.

I would really welcome a technical discussion of equalization by more technically knowledgeable folk than myself. I'd especially like to learn about using solar panels to drive this process, what current limitations really exist, what chargers or voltage controllers are considered reliable on sailboats, etc.

dj
 
Feb 26, 2004
21,141
Catalina 34 224 Maple Bay, BC, Canada
There is only one thing missing that I would really like to hear about: equalization.
dLj, that's because it was covered by Maine Sail in many of his other topics on battery charging and this is just one of many, and this is more about external regulation rather than the different stages/phases of charging. I did an advanced search on "equalization" by Maine Sail. This is one of them: https://forums.sailboatowners.com/index.php?threads/marine-battery-chargers-installation-tips-considerations.136765/#post-877644

You're right, it's part of the process for ONLY the proper type of batteries that can accept equalization.
 
Feb 6, 1998
11,264
Canadian Sailcraft 36T Casco Bay, ME
This is a very informative write-up. There is only one thing missing that I would really like to hear about: equalization. You talked about the other stages of battery charging and touched on sulfation, but you didn't talk about equalization. Many years ago, I spent some time on a sailboat that was owned by an electrical engineer that had worked at Hoover Dam. He and his wife were at that time retired and living on their sailboat. He told me about equalization and how it breaks down sulfation products in the battery. Not that it's perfect, but it certainly helps extend battery life. Ever since learning about this, I have performed it on all my boat batteries and my car batteries since then. I typically get between 15 and 20 years of life out of my batteries quite consistently. Your mileage may vary...
If you are getting 15-20 years then something is working in your favor, but it's not likely to be EQ. If I did not know better I would guess you have GEL batteries or industrial batteries like a Rolls or similar. By industry standards a battery is considered dead when it can no longer deliver 80% of its original 20 hour Ah capacity rating. I routinely see this occur in less than 2 years with the typical automotive case size batteries typically used on a Hunter 30.. Even just calendar life kills most basic flooded batteries before 15-20 years and that is without any cycling at all.

I don't generally talk about EQ with voltage regulators or solar because it is simply too much of a PITA. EQ is LOW CURRENT (batteries must be full before you start) and high voltage. This means little to zero load on a marine diesel for 4-8 hours of idling... Wait until you can get to a dock...

I don't think it works on anything other than flooded lead acid batteries.
Lifeline AGM batteries can be equalized but they are currently the only AGM's that can be.. For FLA batteries the biggest reasons we need EQing are due to improper charging by so called "smart chargers", most of which are are not smart at all & PSOC (partial state of charge cycling) use.

In a perfect world deep cycle flooded batteries should be charged at 14.7V to 15.3V yet very few battery charger makers are anywhere close to that with their rather stupid "dip switch" set points.

Tom Hund of Sandia National Labs published data back in the late 90's on FDC votlages & duration and it took some of the industry nearly 15 years to catch up and others still have not. US Battery was one of the first to recognize that higher charge voltages in PSOC use led to better life but Trojan & Rolls only recently adjusted their guidance. (See below)

During that period it was brutal getting customers to charge at more than 14.4V until the manufacturers ponied up. This was because owners kept pointing at the manufacturers voltage guidance, which while pretty safe, was and is murder on PSOC use batteries. Stack a low charging voltage on top of "premature-floatulation" and it is a death sentence for batteries. Charge at 14.7V to 14.9V and extend absorption to 4-6+ hours and your need to EQ will be reduced quite a bit.


Yep Trojan now recommends 14.82V yet how many "marine" battery chargers even allow for this? Most are still set at an archaic 14.2V to 14.4V.. This is why I always recommend battery chargers, voltage regulators and solar controllers that have a "custom" configuration option. If they don't offer owner customized settings, simply walk away and buy a quality piece of charge equipment.

Some of the key takeaways of the Sandia Data:

"The appropriate regulation voltage for the finish-charge (finish charge means absorption) should be well above 2.40 vpc (14.4 V). The test results from the above work indicate that a regulation voltage near 2.55 vpc (15.3 V) resulted in the lowest capacity loss during 60% discharge cycles. Note that in many cases, the 2.55vpc and the 3- or 6-hour finish charge time was inadequate to maintain battery capacity."

This is saying:
14.4V is far too low for deep cycle flooded batteries and even a 6 hour absorption, at 15.3V, may not be enough to get deep cycle flooded batteries to 100% SOC! And we wonder why we kill flooded batteries so fast...


"As shown above, the capacity of L-16 batteries can be recovered with an equalization charge in this case consisting of 12 hours at 2.55 vpc (15.3 V) regulation voltage. If the L-16 must be operated for an extended period of time in a deficit state of charge, then the finish-charge must be correspondingly longer. The equalize charge can easily become impractical for a PV hybrid system, therefore, it is important to ensure that the engine generator will provide a finish-charge at regular intervals of 1-week or less."

This is saying:
If you PSOC cycle the batteries equalizing with solar is impractical because it would require 12 hours to do so. It is also saying that when you PSOC cycle your absorption duration needs to be much longer. It is also saying that you need to get back to 100% SOC at least "every week or less".

"Other factors also need to be considered in selecting the regulation voltage. These factors include water consumption (higher regulation voltage, more water consumption), daily depth of discharge (shallow cycles, less electrolyte stratification), and time at regulation voltage (finish-charge time is a function of regulation voltage). Each PV hybrid system will have its unique charging requirements; therefore, the system designer must be knowledgeable about the batteries and their charging requirements."

This is saying: Each system is unique and each owner needs to figure out the optimal absorption voltage and duration at absorption voltage based on their needs and use. It is also saying that absorption voltage is directly related to absorption duration. In other words if it takes 6 hours at 15.3V to hit 100% SOC then at 14.4V hitting 100% SOC will take significantly longer, much longer than we have sun up in each day.

Summary:
*Charge at significantly higher voltages than 14.4V
*Higher absorption voltages result in shorter times to 100% SOC
*Charge at significantly longer absorption duration's than most chargers allow for
*Get back to 100% SOC at least weekly but better if more frequent



A true EQ is not really done as the charger makers want us to believe, but is the only practical way of doing it in the field.. The way a manufacturer would do it, and some call it a reforming charge, is to charge from a very low SOC such as 0% SOC / 10.5V and use a very low charge current such as .005C to .01C (0.5A to 1A for a 100Ah battery) and to let the voltage wind up where it will. With healthy batteries it can go over 17V towards the end of charge but requires in excess of 100 hours to do so...



West Marine publishes the voltage range of 15.5 to 16.2 volts for equalization but my (often faulty) memory seems to have 15.8 to 16.2 volts as the appropriate range. I am using an old (1970's) Lambda programmable ( both voltage and current) power supply to run my equalization cycles as I can program that power supply controlling voltage to within about 0.05 volts. I have no idea how precise the current output runs, but I image pretty tight. I don't have to worry about the current side as the maximum output of this particular power supply is 1.3 amps. I wish it would go to 2.5 amps, but I can't afford a power supply of this precision today, so I just deal with fairly long equalization cycles. I tend to take somewhere around 18 hours to produce a fully equalized battery at this output level. It does depend upon how badly the battery needs to be equalized and the size of the battery.
EQ's in the field should ultimately not begin until the bank is already at 100% SOC with your existing charger. If you do that even a 1.3A power supply should be able to push individual batteries over 15.5V. EQ should always be temp compensated and done at manufacturers voltage guidance.

I do not know what the maximum current should be, but I seem to recall somewhere in the range of 2.5 amps, but the real constraint is that the battery can not heat up during this process. I don't know what kind of time periods would allow complete equalization if the current were to be increased above my limited 1.3 amps.
I use power supplies here in my shop for all battery charging. I have three BK Precision 60A units and two Mastech units, a 30A and a 50A. Once the batteries have been fully absorbed, usually 8+ hours at target voltage, with a tail-current of sub 0.5% of Ah capacity, I turn up the voltage to desired EQ level then reduce current to just enough to maintain the target voltage. This yield a "safer" equalization so that if a chunk of a plate breaks free and there is an internal short I am not throwing an additional 30A - 60A at an internally shorted battery. In my experience you always want to use the lowest current you can to maintain the target EQ voltage. Ask me how I learned this...... D'oh!!

Please keep in mind that if you are not EQing regularly, once per month minimum, it can't help a ton. Once sulfation hardens and clumps it is dead. No amount of EQing will bring it back to life and turn it into active material.

Think of sulfation as dead skin cells, if you keep the skin well moisturized the skin cells are alive for longer. Moisturizing lotion here is the equivalent of proper absorption voltage and absorption DURATION.. Folks routinely ignore absorption duration even if they get the voltage correct. Once you let the skin dry out the surface cells are dead, and no amount of lotion, will make the dead skin alive again. Once the sulfate is hard and clustered no amount of EQ will bring it back, all it can do is help drop it off the plate to the bottom of the case.

The effects of sulfation actually happens far faster than folks assume it does. In a 30 cycle PSOC (partial state of charge cycling) test done for Practical Sailor (May 2015 & August 2015) one popular AGM battery lost 1% in capacity for each PSOC cycle or 30% of it's Ah capacity lost due to sulfation in just 30 cycles.. All batteries in the test were charged at the maximum allowable voltage, per the manufacturer, but they were never brought to 100%. While some PSOC resistant batteries such as Firefly shook it off and lost 0% others did not fair as well. Even after the Lifeline battery had been equalized (the only one that could be) its net Ah capacity lost in 30 PSOC cycles was 11%. This is how fast the effects of sulfation occur and permanent capacity is lost. This is why it is best to set long absorb times and to use the highest allowable absorption voltages. If you get back to 100% SOC twice weekly you'll do significantly better than once every week or even once every two weeks.

I would really welcome a technical discussion of equalization by more technically knowledgeable folk than myself. I'd especially like to learn about using solar panels to drive this process, what current limitations really exist, what chargers or voltage controllers are considered reliable on sailboats, etc.

dj
These are feature sets on regulators and solar controllers that I believe have little merit on boats, unless it is an absolute necessity. With solar, the issue becomes hours of solar daylight. Most boats, despite owners believing they hit 100% SOC each day, do not hit it each day. In order to begin an EQ you would need to be at a true 100% SOC before starting the EQ process. If you start early in the AM with dino sources and charge approx one hour beyond the absorption point, then let solar take over (with all ships loads off), you could possibly get an hour +/- of EQ in towards the tail end of the day.

Even some of the fastest charging AGM batteries still take 5.5 +/- hours to hit 100% SOC with a charge current of .4C. This is a 40A charge current for a 100Ah battery. In other words if you had a 600Ah bank of Lifeline AGM batteries and a 275A alternator that could produce 240A when hot, and you don't drop to float "prematurely", it's going to take you close to 5.5 hours to hit 100% SOC. 100% SOC with solar is possible but you'd really need to begin your day at 100% SOC to then run the EQ and this is really not very feasible with a cruising boat. My point here is you are trying to run two full charge cycles in a single day that can really only produce 4-5 hours of reliable irradiance or barely enough to even get the batteries to 100% SOC without using fossil fuels to help it get there..

When ACTIVELY CRUISING With *Flooded Deep Cycle Batteries (*real batteries not G24, 27, 31, 4D or 8D)
Charge at 14.7V to 14.8V (critical for PSOC applications)
Sense voltage correctly
Disable float for solar / set it at 14.2V - 14.4V
Set absorption to 3-6+ hours for all charge sources (easier said than done with sub par equipment)
Set float for alt reg at 14.2V - 14.4V
Keep using lab power supply for EQ
If you go below 12.2V (under load at average house loads) follow that up with a 100% SOC recharge ASAP
Re-charge to 100% SOC twice per week or weekly at a bare minimum
 
Nov 26, 2008
1,910
Endeavour 42 Cruisin
100% every week? EEEk. I'm on a mooring for the winter. Voltages are running 14.8 occasionally but usually 12.8 to 14.0 and never below 12.6. Water consumption is very low. Mostly solar, some wind and occasionally engine alternator when I take a run to the fuel dock for water.
I'm thinking I'll need to get a slip for a night to plug in and charge but I might need 2 nights to get to 100% and then EQ... Every week?
 
Feb 6, 1998
11,264
Canadian Sailcraft 36T Casco Bay, ME
100% every week? EEEk. I'm on a mooring for the winter. Voltages are running 14.8 occasionally but usually 12.8 to 14.0 and never below 12.6. Water consumption is very low. Mostly solar, some wind and occasionally engine alternator when I take a run to the fuel dock for water.
I'm thinking I'll need to get a slip for a night to plug in and charge but I might need 2 nights to get to 100% and then EQ... Every week?
Charge in bulk, in the AM, with the dino juice, and then let solar take over. If you can't get to 14.8V during sun up hours you'll want to listen to the dino juice a bit longer or even add more solar. 12.8V to 14.0V is not even getting you out of bulk and results in chronic PSOC. Once you get to 14.8V/Absorption it still takes many hours to get to 100% SOC.
 
Nov 26, 2008
1,910
Endeavour 42 Cruisin
I havent been to 100% in 6 weeks and if I stay on the mooring all winter, I wont get to 100%. Wandering from around 70% to 80%. 2 nites at the dock is $$$$, over $100/nite; so being the cheap-azz sailor I am, what is the minimum I can get away with?