Catamaran charging system

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Catamaran charging system

Postby Drane on Fri Nov 02, 2012 11:59 pm

We're having problems with the charging system on a catamaran. We have an alternator on each engine, a double-belted alternator on a generator, solar panels and two wind generators, though the wind generators are not hooked up at the moment. The engine alternators are regulated by one Next Step 12P, the generator alternator by a Next Step NS2. The solar panels have their own regulator as do the wind generators. We have 10 8D gel cell batteries in one bank for storage, for a total of 2200Ah. We use an EMON II to monitor the entire system.
The boat was forced to sit unattended for a couple years, and now that we've returned, it seems that the engine alternators aren't charging as well as they used to. The stbd engine alt will put out at best 20 amps and the port engine alt shows negative amperage on the EMON when it is being used. These alternators are 105amp, iirc. The generator alternator (165amp) does all the work now, and puts about 90 amps max according to the EMON.
Both Next Step regulators appear to be operating correctly. We've checked field and power voltages and all led lights appear to be correct for bulk, absorption and float cycles. We took the stbd alternator to an auto electric store and they bench tested it and said it was working fine. We put the stbd alternator back in and hooked it to an old battery for further testing. It started to get extremely hot (over 200F) and we shut it down after the smell started to worry us. We hooked the alternator back on the main battery bank. It did seem to charge at 20 amps, but was still extremely hot. We've since disconnected the stbd alternator (removed the field wire).
Any insight into what is wrong (including the port alternator) or what we can do to further narrow down the problem would be appreciated.
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Re: Catamaran charging system

Postby Coulomb on Wed Nov 07, 2012 12:35 pm

Maybe you have more confidence than we do about the ability of the local alternator shop to do a full diagnostic on the alternator, but it sounds like an alternator issue.
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