Charging Voltage from alternator

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boatboy

Inactive Member
We recently replaced our older standard wet cell batteries with 430 ah of gel batteries. I have historically been very bad at maintaining standard batteries, so I look forward to getting a long life out of these with no worries. However I do unfortunately have one worry remaining.

At the same time I replaced the batteries, I also replaced the old "dumb" charger with a new "smart" charger. This of course has a setting for gel batteries so they get the proper voltage. My understanding is that they do not want to see more than 14.1 or 14.2 volts at most. So I've got the dock charger covered, but the alternator is now an issue. It seems to put out something just under 15 volts. I don't want to fry my new batteries, but I would also like to put off buying a new alternator for a bit. I don't think there are any adjustments available with the internal regulator. Am I wrong? Is there an otherwise simple solution to knock down the voltage?

At some point I will want to replace this alternator with a higher output model that will need an external regulator. Can I go ahead now and buy a regulator and run the "preregulated" output of my current alternator through it?
 
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Geoff Johnson

Fellow Ericson Owner
I am sure you will soon get a more expert answer, but my understanding is that the OEM regulators are set at a voltage (about 13.5-7 volts) designed not to fry your batteries. The downside is that they never really overcome the internal resistance of the batteries and completely charge them. An external regulator will (depending on the battery setting) bulk charge at about 14.4 volts and then drop back to 13.2. If you try to charge your batteries with a stock 50 amp alternator and an external, three stage regulator with your batteries that can accept 100 amps (25% of capacity), you will probably burn out the alternator in short order. You really need to replace the alternator and regulator.
 
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ted_reshetiloff

Contributing Partner
Geoff is right on the money here. First thing I would do is see exactly what alternator you have. Once you know that you will know how it is regulated. Most alternators on boats like yours (speaking very broadly here) have external regulators. You can buy, for less than $200, a programmable regulator. Xantrex makes a nice one. I own theirs. Doesnt matter if you have a 50 amp or 250 amp alternator once you have a programmable regulator. The regulator lets you set the charging profile to meet your battery type. This is exactly what your AC "smart charger" is doing. The regulator sets voltages for bulk and float charging, it also will limit the amperage to a level your battery can tolerate. I have a 100 amp alt. and the Xantrex regulator. I routinely see 75-80 amps after running my batteries down to 70%. I have a 200AH house bank, use a combiner to charge my starting battery, a Xantrex 20amp True Charge AC charger, and a Link 10 to monitor it all. If you really have 450AH of batteries you will need one hell of an alternator to top them off in anything short of a few hours. Thats one hell of a big bank for a 39 foot boat. How are your getting there? 8D's? I have redone most of the electrical system on my E 38 and my older brother works for a company here in Annapolis (Yacht Electrical Systems) that specializes in electrics and state of the art sytems for sail and powerboats.
 
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boatboy

Inactive Member
batteries

We have one 8D (230 AH) and two group 31 (97 AH ea.). We decided to move up to this large bank after changing out our old (and broken) refrigerator that used to be engine driven/110VAC to a 12 volt holding plate system. When we are away from the dock we did not want to worry so much about constantly topping up the batteries to keep them in the safe buffer zone. This upgrade slightly more than doubled our old capacity.

If I get one of these Xantrex programmable regulators, can I feed it the output of my current alternator? While it has it's own built-in regulator, it seems to be sending out much too high of a voltage (about 14.8v). Or do I really just need to bite the bullet and get a new alternator?

If it's reasonable, I am trying to avoid the new alternator right now for two reasons. One is cost. We have just been throwing a lot of money into the boat recently, and it would be nice to spread it out a bit. Second is a time crunch. We will shortly be leaving on a three week cruise down the coast and already have a pretty full schedule trying to get items checked off of the to-do list.
 
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Geoff Johnson

Fellow Ericson Owner
I would send an email to Balmar and/or Ample Power, but from what I have read a three or four stage regulator used with a battery bank your size will try to draw so much power from the OEM alternator that it will fail in short order. Those alternators were really made to top up automobile batteries at not more than 35 amps. The rule of thumb is 25% of your battery bank capacity. Another thing you need to check with a new alternator is that after a certain size (100 amp?) you have to use two belts, which just magnifies the problems of installing it. I installed a 75 amp Balmar with three stage regulator on my Universal M25 in an afternoon and I don't have any particular expertise in boat wiring.

In any event, 14.8 volts is way too high and will destroy your new batteries. If you can get ahold of Nigel Calder's book on boat mechanic's, you will learn everything you need to know on this subject.
 
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Lew Decker

Member III
Assault and batteries...

Hi Greg - Thanks again for the help in past with the interior measurements, etc. The boat is done and looks fine.

You are a whole lot more active in sailing than I am. I get out once or twice a week to sail or putt-putt. We made one trip to Catalina last year, and that is the sum total of our cruising adventures. My family doesn't share my enthusiasm and I solo most of the time. I love the E39B, though.

I have a high-output alternator, a smart charger, two 27 and two 31 AGM batteries. I have to admit that I don't know whether there is an external alternator. I never checked. There is a voltmeter on the bulkhead just below the companionway ladder. It registers a consistent 15-16 volts from the charger when I'm tied to the dock. I was concerned at first but nothing ever fried and the batteries are always topped up. This has been the status since November of 2003 when I installed the charger.

Maybe there is a glitch in the system that allows the high charge rate, or the voltmeter is botched up, or I have shortened the life of the batteries, or I don't have a clue what I'm talking about. All I know is that everything works except that the house bank went dead flat in a week once when the circuit breaker on the dock was tripped. I tried to find the source of the battery drain and gave up after a day of isolating one circuit after another. I used to be a good electrician. At my young age of 60, though, my patience is gone and I've forgotten everything I used to know. Our autumn years ain't for sissies.

I will watch for more responses to your post. Maybe someone has some solutions/suggestions to address your electrical gremlins that can be applied to mine.

How far are you planning to sail down the coast? I've thought about beating up the coast but then I wake up and see my boat bashing into cold headwinds and cold combers rolling all the way down from Alaska. Maybe I'll pass. I spent years in Florida and the Caribbean and I think I'm jaded. :)
 
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boatboy

Inactive Member
Alright, I guess it's sounding like I just need to take a deep breath and get the whole thing over with -- new alternator and regulator. I definitely don't want to risk frying these new batteries on the cruise.

Lew... we'll be going as far south as Catalina. If you were interested in rendezvousing out there for an overnighter, that would be fun. I would definitely like to see what you've done with your boat. We'll be departing from SF Bay on Saturday the 9th and heading directly to San Pedro -- where my Dad lives. That should take about three days. After a day or so of rest, we'll head out to the island.
 
footrope

footrope

Contributing Partner
Blogs Author
Xantrex programmable regulator

You need an external regulator that can be used with Gel Cell batteries. You may have to get a new alternator if you can't use an external regulator on the model you have, or you need higher output amps. You definitely need an alternator that will allow you to connect an external regulator. You also want to figure out what type of tach pickup your engine uses. My Universal 3240 (M-40) RPM gauge gets tach signals from the alternator. You need this info to restore your tach signal if you get a new alternator.

As for alternator output amps - I have a new Presolite 51 amp alternator (the original was 55 amp) for the engine start battery (a gel cell) and a 190 amp alternator for my 400 AH of AGM house batteries. It would take a long time to charge my house bank with the 51 amp alternator. I don't necessarily recommend a second alternator, but you do need to look at battery switching that will allow you to isolate your house and engine banks. You also need to switch the regulator sense line when you switch the alternator between banks. Switching is an area where I haven't done much work since I have two independent alternator charging systems.

Gel Cell batteries need 14.1 volts for the bulk charge cycle - confirm that with the supplier or manufacturer. The Xantrex XAR regulator has a pre-programmed setting for Gel Cells that should work. You should use a digital voltmeter to determine if you got the program setting correct.

All the above is assuming you want to do it yourself. If you have a pro do it, or can get a pro to help you do it, I would recommend you do so. I learned alot last summer working through my two-alternator two-regulator system problems. I blew one regulator during my troubleshooting and that cost me almost $400 ($70 for a pro to confirm a bad alternator which convinced me to give up, $275 for a backup regulator to get me home, $50 for the repair of the blown regulator).

Good luck and have a great cruise.
 
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Geoff Johnson

Fellow Ericson Owner
I didn't know you could blow a regulator (as opposed to the diodes on the alternator). How did you do that? I know someone who blew the diodes on both the main and backup alternators two days into a six day trip to Bermuda. Nothing like hand steering a dark vessel in the middle of the Atlantic with a flashlight taped to the compass.

I think all the new smart regulators are programable. On my Balmar 612, you just swipe it with a supplied magnetic wand until you get the charging regimen you want (AGM in my case). Since I did the work myself, I bought both the alternator and regulator from Balmar so that in the event of a problem I would not have two manufacturers trying to foist the problem off on each other. Balmar's instructions are very good and easy to follow. My major challenge was to change the bracket for the alternator since the OEM bracket on pre-1988 Universal M25 engines is defectively designed and prone to breaking. There is another thread on that on this site.

As for the volt meter, I have a Link 20 which is very useful for reading the voltage and amperage into each battery. However, the newer networked chart plotters (at least Garmin) also read voltage, so if you have plans to get one, you could save money on the volt meter.
 
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Lew Decker

Member III
Batteries included?

I think I'm getting a headache...

The PO installed the new AGM batteries some months before I bought my boat but the charger was an old "go-no go" affair that kept charging at a 16 volt rate. I replaced the charger with a new unit that was switchable from lead acid to gel to AGM but, lo and behold, the charging rate stayed at the 16 volt level. Since nothing ever went wrong with the system, I left it all alone thinking if it ain't broke, yadda, yadda, yadda...Maybe it is broke? The old charger probably fried the plates and I'm living on borrowed time. Have any Tylenol?

Greg...I will think about Catalina. My daughter won't be going back to school until the end of the month. She'd love go with me but it's a question of time and those Alaska rollers. She's prone to get seasick. Drop me an email if you can when the time approaches. Maybe some other Ericsons can join us?
 
footrope

footrope

Contributing Partner
Blogs Author
Blowing a regulator

My two old regulators are Cruising Equipment Alphas - pretty good units - which are still supported and repairable by Xantrex up here in Washington. The way to blow one is to connect it to an alternator with a shorted rotor. When my house charging system failed, hindsight says that the alternator rotor shorted first, which then caused the first regulator to blow. Why do rotors short?

While troubleshooting (one of several steps) I took my good regulator off the engine system and subbed it on the bad house alternator, which promptly blew it. The next thing I did was have the pro come down, and he used a little device that simulated field voltage and measured output voltage - which was fluctuating wildly. Dead alternator and two dead regulators. I thought I had bad diodes, but they were ok, according to the rebuilders.

The electrical parts guy up at Marine Servicenter at Anacortes got the Xantrex freighted up from Seattle the next day. The Xantrex XAR, btw, uses the identical plug as the Alphas. I think the Balmars are the same, too. He also called around to Xantrex Customer Support and got me in touch with their repair people. A couple weeks and $107 later I had my old regulators repaired. The rest of the story (which I think is on another thread somewhere) includes getting the new 51 amp for the engine.

I decided to hold the Xantrex out as my spare since it was so easy to set with the magnetic wand. Not that the Alphas were difficult to set either. The Balmar and Xantrex regulators are eerily similar, so I suspect one resells the other's unit with their own paint job. A regular Kenmore-Whirlpool deal.
 
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boatboy

Inactive Member
I did it. I'm now about $600 poorer, but have a new 110A Balmar alternator and regulator begging me to install them. Hopefully I'll get it done this weekend with relatively few problems. It looks like the original alternator mount will work just fine with this new one. I figured my wallet would eventually recover, but my batteries would never be the same if I didn't do it the right way.
 
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ted_reshetiloff

Contributing Partner
This is more for you E 38 owners but others can chime in. Where are you guys putting all of these batteries? Do your boats float on even lines or do you have the starboard list? I have 2 group 31 gels and a 27 starting battery all on the starboard side under the seat. PO replaced the port side water tank 40 gal. with an AC unit which I love, but I have a slight starboard list and want to relocate my batteries.
 
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boatboy

Inactive Member
Just to finish off this thread, last weekend I installed the new Balmar alternator and regulator. The charging is now exactly as it should be, and I happy to no longer worry about the batteries.

In answer to an earlier question, we have our batteries mounted under the bunk in the aft cabin. They are as close as possible to the centerline, which still leaves them a bit to starboard of the centerline. We would have loved to get them on the port side of the boat because we also have the starboard list, but this seemed to be the only practical spot.
 
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Lew Decker

Member III
One last jolt...

Greg - I have one bank in the portside locker that opens toward the stern in the aft cabin. The other bank is beneath the double bunk but completely exposed to engine heat. In the future I will move those to the aft locker if I don't bake them first. That might help with the starboard list.

It just occurred to me your arrangement might be different. Is your locker beneath the double berth floored in? Mine is open to the engine. There is also a hot water heater stuffed in the same space.

I looked but couldn't find a regulator. I thumped the voltmeter, though, and the needle dropped to 14.8V :) . Still too high, but better than 16V...

You did the right thing installing a new alternator, etc. I will probably keep my head in the sand until I have catastrophic failure of the entire universe.

I'm still thinking about Catalina...Keep me posted.
 
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footrope

footrope

Contributing Partner
Blogs Author
Battery locations = port list

I have two house batteries under the aft berth at its forward end - that would be on the port side. The other two house batteries are under the aft dinette bench but as far inboard as possible - but also slightly to port. The engine start battery is under the nav station seat, inboard end - port side of centerline. My 38 lists a couple degrees to port.

Cheers,
 
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boatboy

Inactive Member
Hi Lew,

Yes, the storage space below the aft berth is floored in. It is still somewhat exposed to engine heat due to proximity, but it sounds like not nearly to the degree yours is. When we decided to add the 8D battery, I explored locations all over the boat -- but this thing is a beast in size and would not easily fit in the aft locker without losing a lot of it's space (we also sometimes put wet foulies in that locker). Because the water heater located under the aft bunk occupied a perfect size space, which was also right next to the other batteries, I decided to move that into the aft locker and have the 8D take up it's old home. This also prompted me to actually replace that water heater with a new one, as it's casing was rusting away into nothing. The new water heater has an all stainless case and fits nicely in the aft locker.

I'll write you personally about Catalina.
 
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rssailor

Moderator
Temp sensors

Greg,
Did you get both of the temp sensors for your regulator and did you get the max charge regulator? If not pick up the temp sensors, and hook them up according to wiring diagram. Good choice, Balmar stuff is first rate. Ryan Moonglow Ericson 25+
 
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