Converting An Alternator To External Regulation

[Stu Jackson]

Bill's right - it's a SYSTEM

Question?
Would you recomend using a 3/8 or 1/2 belt with a 90 amp alternator. I was reading Caldor's book last night and it's quite an interesting project selecting the right combination of belt/pulleys.

You need to advise what engine you have. The whole alternator belt sizing is SO way over discussed. MS is right, you're gonna be lucky to get 50 A outta your 90 A alternator because of "battery acceptance" even with a 1/2 full house bank. Search on that phrase to get to some very good recent discussions about that subject.

If you've got an M25 or even an M35 series Universal, a 3/8 belt works just fine, but tension it properly. See reply #21 http://c34.org/bbs/index.php/topic,4454.15.html

Some use 7/16 belts. I have a 100A with the 3/8 belt on our M25 (1986) engine. We also purchased and use the belt tensioner.

Don't overthink the belts and pulley thing. Calder does, you don't need to.

 

[Twice Around]

Hi...resurrecting an old thread. How hard would it be to convert an original 35amp Motorola from an Atomic 4 to work with a Xantrex external regulator #84-2006-01.

I realize it is a 'weak' alt. by normal standards, but I have mostly switched to LED lighting, have minimal electrical demands, and I am trying to upgrade my charging system in affordable stages. I have two functioning Motorola alternators, so there is no current reason to waste $$ on new alternators. The question is can I make the Motorola work with the Xantrex unit?

Thanks for any input.

 

[Steve Dion]

There is a manual that list many of the most popular alternators that show one exactly what needs to be done for each type of alternator. I will see if I can find the name of the manual.

 

[Maine Sail]

Hi...resurrecting an old thread. How hard would it be to convert an original 35amp Motorola from an Atomic 4 to work with a Xantrex external regulator #84-2006-01.

I realize it is a 'weak' alt. by normal standards, but I have mostly switched to LED lighting, have minimal electrical demands, and I am trying to upgrade my charging system in affordable stages. I have two functioning Motorola alternators, so there is no current reason to waste $$ on new alternators. The question is can I make the Motorola work with the Xantrex unit?

Thanks for any input.

What are you hoping to gain or achieve by converting to external regulation? Do you know the voltage target or set point on your existing regulator eg: 13.8V, 14.2V, 14.4V, 15.0V etc. etc..? Do you have AGM or Gel batteries? How big is your bank in Ah's?

 

[Twice Around]

Maine Sail & others,

Thanks for the post.

MS - I find your work & tips excellent & helpful to a new boat owner like myself, thanks for taking all the extra time to document all the tedious boat stuff!

The driver here is 3-stage charging on a budget & building on future plans, plus I found someone selling a used Xantrex cheap.

I am hoping to slowly upgrade my charging system and make it more modern..in as systematic a fashion as I can, and on a budget. I know those don't go hand in hand very well. I currently have modest electrical requirements..cabin lights (90% LED), a pressure water pump, and a laptop I like to carry for backup navigation. In this day & age of gadgets, we are also constantly charging smartphones, handheld GPS, MP3 players, etc..
As we do more cruising, I am considering adding refrigeration to the icebox, and after I re-wire the boat, I'll add fun things like a stereo and maybe a few more electronics..my instrument system is currently a simple Raymarine ST-40 depth/speed combo. With an amp hog like a refer, I plan to incorporate a larger house bank in the re-wiring effort, hence the research & questions.

Here is my current setup:
#1 - I have flooded batteries - one group 27 house, and one group 24 start.
#2 - I currently have an adjustable (I assume single stage) regulator on the Motorola - link --> http://www.ase-supply.com/product_p/trs-m5-197a.htm - this unit has served me well, and taken care of the initial problem of chronic undercharging with the old 13.8 volt regulator AND the isolator in line. (how the boat came from the P.O.)
#3 - I have an old Powerline isolator (sucks up ~0.7v), so, I have the regulator set around 14.9-15.0v to give me ~14.2v at the battery post at cruising speed.
#4 - I moved the ammeter from the cockpit to the engine room to eliminate the long run. My charging cable goes from the alt. to the gauge to the isolator to battery posts..total run about 48-54" inches.

My research has also led me to some more questions. How do you figure out if your 35 year old alternator is a P or N type? Can you convert an N type to work with a Xantrex since it seems to want P type alts? I also realize that a 35amp alternator may not be strong enough for future power requirements. However, at that time I could purchase a replacement alt. that is compatible with the Xantrex & more powerful to more effectively utilize the fancy 3-stage charging.

Thanks for the advice.

 

[Stu Jackson]

If you reread this entire thread, MS already answered that question.

 

[Maine Sail]

Maine Sail & others,

Thanks for the post.

MS - I find your work & tips excellent & helpful to a new boat owner like myself, thanks for taking all the extra time to document all the tedious boat stuff!

The driver here is 3-stage charging on a budget & building on future plans, plus I found someone selling a used Xantrex cheap.

I am hoping to slowly upgrade my charging system and make it more modern..in as systematic a fashion as I can, and on a budget. I know those don't go hand in hand very well. I currently have modest electrical requirements..cabin lights (90% LED), a pressure water pump, and a laptop I like to carry for backup navigation. In this day & age of gadgets, we are also constantly charging smartphones, handheld GPS, MP3 players, etc..
As we do more cruising, I am considering adding refrigeration to the icebox, and after I re-wire the boat, I'll add fun things like a stereo and maybe a few more electronics..my instrument system is currently a simple Raymarine ST-40 depth/speed combo. With an amp hog like a refer, I plan to incorporate a larger house bank in the re-wiring effort, hence the research & questions.

Here is my current setup:
#1 - I have flooded batteries - one group 27 house, and one group 24 start.
#2 - I currently have an adjustable (I assume single stage) regulator on the Motorola - link --> http://www.ase-supply.com/product_p/trs-m5-197a.htm - this unit has served me well, and taken care of the initial problem of chronic undercharging with the old 13.8 volt regulator AND the isolator in line. (how the boat came from the P.O.)
#3 - I have an old Powerline isolator (sucks up ~0.7v), so, I have the regulator set around 14.9-15.0v to give me ~14.2v at the battery post at cruising speed.
#4 - I moved the ammeter from the cockpit to the engine room to eliminate the long run. My charging cable goes from the alt. to the gauge to the isolator to battery posts..total run about 48-54" inches.

My research has also led me to some more questions. How do you figure out if your 35 year old alternator is a P or N type? Can you convert an N type to work with a Xantrex since it seems to want P type alts? I also realize that a 35amp alternator may not be strong enough for future power requirements. However, at that time I could purchase a replacement alt. that is compatible with the Xantrex & more powerful to more effectively utilize the fancy 3-stage charging.

Thanks for the advice.

Post 22 (LINK) will sum up my opinion on your exact situation. You will gain little to no benefit, except a float phase, if you switch from your current adjustable regulator to external.

If you read post 22 and still feel the need the same kit in the OP will and should work on your alt. The Motorola alts ARE the predecessor to the current Leece-Neville alts with little to no changes to the regulator case design.

I think the graph below sums up my feelings. This graph is from a Practical Sailor head to head comparing external voltage regulators to a "dumb" regulator set at 13.8. A rather unfair comparison IMHO and one that only served to further the myth that external regulation is always necessary for a sail boat. Yes, SOME alternators from the 70's and into the 80's came with 13.8 volt outputs. Most current alts, including the replacements for these exact alternators, now ship with target voltages of 14.2-14.6 V not the dreaded 13.8 volts.

We all know 13.8 WILL undercharge batteries but a standard dumb regulator will put out the same amps as "smart" regulator up until the batteries hit 13.8 volts then the smart regulators will continue to charge faster until they hit their voltage set point of 14.2-14.6. Again, comparing 13.8 volts of "pressure" to 14.4 or 14.6 is a totally unfair comparison but one that external regulator companies have preyed upon.

If the "dumb" regulator had been set to 14.2-14.4 in this test the graph would have been nearly identical just as it had been until the batteries reached 13.8 which is where the graph bears off between dumb and smart.

All of the currently marketed external regulators are CV or constant voltage driven NOT CC or constant current. Until the batteries reach the regulators set point voltage the alt is putting out max accepted amps or the limit of the alternator which ever comes first. The dumb & the smart regulators have no idea what the alt is putting out for amps, they are not constant current driven, it is only looking for voltage. If it is not at the set "voltage" it is essentially "open" and applying what the alt can supply or the batteries will accept.

Once the batteries get to 14.2 to 14.4 the batteries are strongly deciding what to accept not the alternator. Batteries by nature accept less and less as they fill until they accept as little as .5-2% of capacity. AGM's accept more than Gels' and Gels' accept more than wets.

If you pushed the set voltage (read pressure) to 15+ you could increase accepted amps slightly but at a potential cost to the battery this is why it is usually only done during the occasional equalization.

Most boaters cycle their batteries between 50 & 80% state of charge when cruising away from the dock and this graph show very, very clearly that up until the batteries hit 13.8 volts, at around 78% SOC, ALL the regulators performed basically identically from 55+/-% SOC to 78% +/- SOC. As I said if the "dumb" regulator was set to the same voltage/pressure as the "smart" ones the curve would have been virtually identical. The only real feature you loose is a float setting and temp sensing.

If you were going to switch to AGM's or Gel's I would highly urge you to upgrade to external regulation but for your situation I would stick with what you have as the only gain will be less money in your pocket..

That converted alternator from the OP is still sitting in my barn. I have TWO "smart" regulators to choose from when and if I decide to install it, I see no need, for my current battery bank and use, to upgrade to "smart" regulation on my wet cell bank even though it is free, ready to go and sitting in my barn.

I am now finishing year four of my Wal*Mart MAXX 29 battery bank and "dumb" regulation experiment and this spring the batteries tested as new with the VERY expensive EXP-800 battery tester. I suspect they will easily give me a fifth, sixth and maybe even seventh season.

Four years old vs. brand new which one is which?

I honestly think your money would be better spent first on a battery monitor and then an Echo Charger or Automatic Combining Relay (ACR) and losing the ammeter and diode isolator.

 

[Twice Around]

Sorry to make you repeat yourself, but I appreciate the information.

I did some more reading, (including reading this thread again) and really can't find a reason to spend the $$, & have come to the same conclusion..ditch the diode isolator someday (replace with an ACR) but don't waste the money on a fancy regulator for my small wet cells.
The ammeter was re-installed in the engine compartment to give me an idea of the amps going in without having it run all the way to and from the cockpit. Right now at certain RPM's I am seeing some fluctuations on the gauge (pulsing) so I need to check all of my connections and see if I have other more pressing issues.

Thanks again.
edit - I forgot to mention that I have a small solar panel as well with a controller..it is only 3.2 watts, but it may be enough to take care of my 'float' needs with that. I switch it between batteries every other time I visit the boat, (primarily on house, but sometimes on the start) since I've yet to need the starting battery to start the A4...so far I've always been able to start it on the house battery.