External regulation

I'll defer to Maine Sail's advice on wiring but the ARS5 has most of the features of the MaxCharge. It lacks a Halogen program that limits the voltage to save your lights and I believe it may also lack an equalization program, but that's best done with a shore power charger anyway. Both have advanced programming modes that'll let you set the voltage and duration of each stage in detail and both have a "small engine mode" that'll cut the alternator load by 50% at the flip of a switch that's wired to short out the alternator temperature sensor.

Bob, if I was in your shoes, I'd go to www.balmar.net and download BOTH the ARS-5 and MC-614 regulator installation manuals and compare them.

Then you'll see the differences.

You could also go to the WM online store and read the descriptions and the specs, like this one and compare the two.

http://content.westmarine.com/documents/pdfs/BalmarMaxCharge614.pdf

and

http://content.westmarine.com/documents/pdfs/BalmarARS5.pdf

The big differences for me are:

#1 MC-614 has a dedicated possitive voltage sense wire & reg B- carries very little.. This means nothing is on the v-sense wire except voltage sensing. It allows for extremely accurate voltage sensing with almost zero voltage drop to the battery terminals. Accurate voltage sensing is a critical aspect to high performance charging.

The ARS-5 shares the B+ power feed for the regulator with the voltage sensing. Seeing as in bulk mode this wire can be asked to provide 7A +/- of current, and the average install I see is using 14GA, and pigtailing off random points in the system (don't do this) rather than the battery, I see lots of inaccurate voltage sensing with the ARS-5 vs. the 614.. For example 7A at 12V on 12' round trip of 14GA wire results in nearly 0.436V drop. This can mean the difference between the reg seeing 14.4V or 13.9V......

With the MC-614 it always sees the actual voltage because the v-sense wire is not also carrying current on it. On our boat I have very expensive LiFePO4 bank. There is currently no regulator on the planet I would feed my expensive LiFePO4 bank with other than the MC-614. Accurate voltage sensing for LiFePO4 is EXTREMELY critical but ALL banks benefit...

Note: With either regulator the regulator negative wire should always be pulled directly off battery neg for the most accurate voltage sensing.

For more on the importance of voltage sensing, see this link:

Alternators & Voltage Sensing - Why It's Important (LINK)

#2 The MC-614 can supply a lot more the field current than the ARS-5 can. With all things electrical they tend to last longer when not asked to work at full bore their entire life, including alternators. The MC-614 can drive two alternators so when asked to drive only one alt it is barely putting forth an effort. Truly coasting along on cruise control...

#3 Second port for battery temp sensing. The MC-614 allows you to monitor two banks or two batteries within a bank for temperature. This can be very useful especially when one engine may be in an engine compartment. Another example is two batts out of four are up against the hot engine room bulkhead and this allows the two batts with the most potential to get warm to be temp sensed.. I had one boat with flag blue topsides and two 4D batteries in a compartment that could hit 120F by noon. The other batteries in that bank were in another locker below it but also in the bilge where temps where compartment temps were in the 60's. The owner refused to move the batts, which would have been the smart move, so I instead sensed the two batts in the sauna and added some ventilation. Engine bays are DUMB places for batteries but builders do it. I use the second battery temp sense port quite often.

#4 Data TX / RX. This is not something we have use of at this point in time but is one that we may hopefully have sooner rather than later. An MC-614 would be ready for what ever upgrade or tool Balmar may provide in the future but the ARS-5 would not. This could be a remote, remote programing tool, diagnostics, flash updates to the chip etc. etc...

#5 This may have changed in the last re-flash of the ARS-5 but the newer MC-614's (post July 2011) use "smart" temp compensation. The old temp compensation used to simply cut alt output by 50%. The alt would then cool and it would revert back to 100% and repeat the dance all over. The new "smart" temp sensing drops it in stages until it finds the happy medium and the max point at which the alt can run cool and stay below the AL1 set point.. The MC-614 has had this now since July of 2011 and I am unsure whether the ARS-5 does or not. I still use belt/amp manager as my primary current limiting tool but the new "smart" temp compensation is a tool many of us in the industry were asking for, and Balmar delivered.

IMPORTANT NOTE: Voltage sensing and alt output MUST go to the same bank. Neither can be switchable or the reg will not see a bank getting charged and drive the bank being charge to 17+ volts. I see this quite often in DIY installs and also see the fried batteries to go along with it. The most recent was A DIY wiring mishap that had an 8D Lifeline starting battery, in a big power boat, that had been seeing in excess of 17V for 4+ months..... That $500.00+ battery was literally destroyed in under six months.....

For example Darryl & his other brother Darryl wire up their new alternator and hook the volt sense wire to the house bank, this is good! However they decide to leave the alt B+/output connected to the 1/2/BOTH switch, this is BAD!

All is fine when the switch is set to the house bank but then one day Darryl #2 sets the switch to the second bank. They head of in ignorant bliss. Meanwhile the regulator is trying its hardest to raise the voltage of the house bank but is is seeing ZERO change. Because it is not getting a voltage response it continues to full field the alternator!!! The voltage of the second bank is now in excess of 17.5V!!!!


For the extra $40.00 or so I find the MC-614 to be well worth it, but if budget is tight the ARS-5 is still a great reg....

Newport Bob said:

- If I understand your original post you recommend wiring the regulator output directly to the house bank. How do I wire from there to charge the start battery?

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Echo Charger, Duo Charger or an ACR/VSR relay.. All work behind the scenes seamlessly to charge an AUX or Start bank.. The Echo Charger has a max of 15A, the Duo Charger can do 30A and has a batt temp sense option plus voltage adjustments. An ACR/VSR simply combines the two banks once a charging voltage is sensed. It disconnects when no charge voltage is present.

Be sure to fuse the alt output within 7" of the battery bank at a minimum of 150% of its rating.

Newport Bob said:

- I think that the eng is marginal for this boat and would like to have the HP to drive the boat if necessary in extreme situations. Can I add a switch in the circuit to take the alt "off line" similar to engine starting delay?

Thanks again,
Bob

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If you want to cut the reg entirely then a simple dash mounted switch in the regulator B+ wire (not the volt sense but the power wire) will do this. Alternatively you can do a 50% cut with small engine mode..... Best to dial any alt back in belt manager so it is not asked for full output for long periods of time.

Voltage drop impacting ARS-5 sensing - comparison error?

You raise an important point about a dedicated sense wire providing more accurate measurement of the charging/battery voltage. However, I don't think it is correct to use round trip wire length when comparing voltage sensing accuracy of the ARS-5 to the MC-614. Only the voltage drop of the wire used for sensing is different between the two models, and only the B+ wire carries any significant current; the ground wire does not.

I assume your "round-trip" calculation includes the ground wire, and unless I am mistaken, it carries the same current in both designs. In neither case will the ~7 amps of field current flow through that ground wire, just the actual current required by the regulator's electronics, probably less than one amp. The current directed to the field winding returns to ground via the alternator's ground, not the regulator's.

So, while the voltage drop on the ground wire does contribute ever so slightly to the reduction of the apparent sensed voltage, it does so on both the ARS-5 and the MC-614. I agree, that if using the ARS-5, one should use a heavy gauge (~10 GA?) for the B+ wire.

Maine Sail said:

The big differences for me are:

#1 MC-614 has a dedicated voltage sense wire. This means NOTHING is on this wire except voltage sensing. It allows for extremely accurate voltage sensing with zero voltage drop. Accurate voltage sensing is a critical aspect to high performance charging. The ARS-5 shares the B+ power feed for the regulator with the voltage sensing. Seeing as in bulk mode this wire can be asked to provide 7A +/- of current, and the average install I see is using 14GA, and pigtailing off random points in the system (don't do this) rather than the battery, I see lots of inaccurate voltage sensing with the ARS-5 vs. the 614.. For example 7A at 12V on 12' round trip of 14GA wire results in nearly 0.436V drop. This can mean the differnce between the reg seeing 14.4V or 13.9V......

Click to expand

The voltage sense wire does not carry much (0.01) current so the voltage drop is almost nil.
The ground side is shared with the alternator output though and any voltage drops there will effect the charge voltage.
ALL connections should be clean and tight as a best practice.

The point is that with the ARS-5 there is no dedicated sense wire, so the sensing is done from the B+ line to the regulator. Since that wire also carries all the current that gets sent to the alternator's field winding by the regulator, the voltage sensed at the regulator will be slightly lower due the drop across the B+ wire length to the regulator (its resistance x current, including alternator's field current). Per MaineSail, the field current can be of the order of 7 amps during bulk charging.

My note was that the voltage drop in that case is due to the one-way length of the B+ wire, not round trip.

Regarding your comment on the "ground side is shared with the alternator output", the ground wire to the regulator is not in the path of the alternator output, it only carries the current consumed by the regulator's electronics, which is very low.

Best,
JR

Bill Roosa said:

The voltage sense wire does not carry much (0.01) current so the voltage drop is almost nil.
The ground side is shared with the alternator output though and any voltage drops there will effect the charge voltage.
ALL connections should be clean and tight as a best practice.

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Well I have an ARS-5 and it certainly does have a post on it to attach a voltage sense wire. It is an option and you have to wire it yourself.
I would note that the a field winding wire voltage has almost nothing to do with the alternator output voltage. The two are related but since you don't know the engine RPM you don't know the alternator voltage by looking at the field winding voltage. Is it close, sure, it can't be more that the alternator output voltage but there is a dedicated terminal (white) on the regulator for voltage sense. Just run a wire from that post to the house battery +.

Balmar's ARS-5 documentation does not show a dedicated voltage sense wire; perhaps you are thinking of the optional temperature sensor wires?
http://www.balmar.net/PDF/ars-5instructionsheet.pdf

The point MaineSail and I were making about the field winding is not about the field voltage; it's that the current supplied by the ARS-5 to the field winding comes to the regulator through its B+ lead, and that produces a slight voltage drop resulting in the B+ voltage at the regulator no longer being an exact indication of the actual battery voltage. The MC-614 solves that by using a separate dedicated wire to sense the battery voltage. Where I differed with MaineSail was in calculating the actual magnitude of the ASR-5's resultant error. I was claiming his calculation inadvertently doubled it.

I beleive that if you look at terminal "2" you will find the battery sense wire. it hs the ON-OFF switch to the regulator.

I stand corrected the terminal "3" is the voltage sense wire. It even states it as such.
I'd suggest you actually read the manual before the install.

Yes, terminal three does the voltage sensing, but NO it is NOT a dedicated sense wire. I did consult the manual and that is why I included the link. The manual states that wire number three,

"Supplies Power to the power regulator as well as voltage sensing input."

The fact that it does double duty is the key difference. The power regulator pulls up to 7 amps (per MaineSail, who has measured it, in order to power itself and the needs of the field winding), thereby causing a slight voltage drop between the battery and terminal 3 of the regulator. This is turn introduces a slight error in the regulator's voltage sensing. Slight, but real. The MC-614 adds a separate sense wire that is not carrying any current, so that the slight error is eliminated. Usually the error is not a big deal, so most owners of the ARS-5 are happy. BUT, if one wants to do a head to head comparison as was requested in this thread, then such differences are well worth noting.

P.S. I went back and added the word "dedicated" to make my post clearer. Thx

Bill Roosa said:

I stand corrected the terminal "3" is the voltage sense wire. It even states it as such.
I'd suggest you actually read the manual before the install.

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Sorry for the confusion guys it is not round trip including the black wire, bad choice of words on my part, it is the max current I have physically measured on the regulator power wire of the reg. The neg wire also carries as much as 0.6A at times but usually closer 0.2 - 0.4A. The v-sense circuit uses the reg B-/neg lead so both v-sense and regulator negative should sense the batt terminals, if you want optimum performance.

Balmar prefers these out of hot engine room thus I see many installations where the run from the reg to the battery is more than 12 wire feet. As I mentioned I have measured as much as 7A on this wire depending on the small case alt, and output. On large frame alts I have measure upwards of 9A.

With the MC-614 there is no current carried on the v-sense wire thus more accurate voltage sensing betwen regulator B- and regulator v-sense/terminal #9. There is only about .5A max carried on the negative lead so this will impact v-sense very minimally.

no argument about the physics but lets put on our electrical engineer caps and think about what is going on when it is operating.
When would you full field the rotor? Not very often as that would drive the voltage to somewhere around 20+ volts. so in practice you almost never see that 7 amps and then not for a long time. The critical nature of voltage control is not that great when bulk charging at 14.4 (the max field current you are going to see regularly). When you really need voltage control and accuracy the field current is pretty low as the alternator is trickle charging the batteries.
What I glean from this is there is an error in voltage when operating at full field relative to trickle charging but it does not really matter.
It is accurate when it needs to be.

.003277 ohms per meter for 10 AWG wire. or 0.001008 ohm/ft.
at 12 ft that is 0.012099 ohm. Since dV=I*dR and
I is the 7 amp field current
dR is the 0.012099 ohms
dV=0.08 volts drop from where the wire ends to the regulator. not what I'd call a serious error at full field.
dV for 1 amp trickle charge and the same 12 ft is 0.012 volts drop.

yawn.

Bill Roosa said:

no argument about the physics but lets put on our electrical engineer caps and think about what is going on when it is operating.
When would you full field the rotor? Not very often as that would drive the voltage to somewhere around 20+ volts.

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The entire time you are in bulk your alt is at full output. With many high capacity cruisng banks this can take two plus hours....

Bill Roosa said:

so in practice you almost never see that 7 amps and then not for a long time.

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You really need to get out more.. Bulk is NOT voltage limited it is constant current charging. Yes Balmar has bastardized the term, for marketing purposes, but bulk is NOT a voltage limited stage of charging it is CC...

Bill Roosa said:

The critical nature of voltage control is not that great when bulk charging at 14.4 (the max field current you are going to see regularly).

Click to expand

EE speak....???? Bulk is CC NOT CV charging. I have piles of banks that don't / can't attain voltage limited charging for two to three hours due to the sheer size of the bank and alt/belt limitations. This is HARD work on an alternator. The boat I was on today has over 640Ah's of AGM's and a 120A alt which runs at 90-95 +/- amps when hot. At 50% SOC it takes well over two hours, at full tilt, for it to hit 14.6V and begin the CV stage where the field/reg begins to cut back. With a real charge rate of about .16C this bank takes about 2.5 hours before it even hits absorption or constant voltage charging.

The alt on my own boat is in bulk/CC for 2.5 hours straight.....

Bill Roosa said:

When you really need voltage control and accuracy the field current is pretty low as the alternator is trickle charging the batteries.
What I glean from this is there is an error in voltage when operating at full field relative to trickle charging but it does not really matter.
It is accurate when it needs to be.

Click to expand

Yep when the batts get full there will be less inaccurate sensing, even on a 14GA wire... The biggest problem with the ARS-5, & other regs, is usually how they are installed and where it is powered from..

I just pulled up a video of an alt set up I did a while back and even at 6A of accepted current (140A alt) the field voltage was about 3.2V and there was still 1.75A of field current... This kind of current on a 12' run of 14 GA wire still equates to about a .1V drop. On that bank 6A = less than a 2% acceptance rate or for all intense and purposes about as full as you would ever get, with an alt, while out cruising yet even at a "trickle" the reg was still supplying 1.75A on the field wire......

Bill Roosa said:

.003277 ohms per meter for 10 AWG wire. or 0.001008 ohm/ft.
at 12 ft that is 0.012099 ohm. Since dV=I*dR and
I is the 7 amp field current
dR is the 0.012099 ohms
dV=0.08 volts drop from where the wire ends to the regulator. not what I'd call a serious error at full field.
dV for 1 amp trickle charge and the same 12 ft is 0.012 volts drop.

yawn.

Click to expand

Yeah it would be great if everyone used 10GA wire but guys like me can only dream about stuff like that.. My initial statement was based on the numerous installs I come across wired with 14GA wire, and more than there should be, for the circuit length.....