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Old 08-17-2017, 06:13 PM   #1
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City: Seattle
Country: USA
Join Date: Dec 2012
Posts: 37
Isolator question

My newish to me boat.. a Carver 350 Voyager.. has twin Volvo TAMD41B engines with a Valeo Rhone alternator on each engine, 51 AMP internally regulated. Both alternators are connected to a Sure Power isolator with two input terminals and three output plus two smaller terminals for which I know not. The two input terminals read 14.68 volts and 14.66 volts. and the two output terms read 13.83 and 13.85. essentially a loss of .8 volts. The other output terminal reads 14.40. This cable is connected to nothing. I suspect that this third cable may have been connected to the generator battery. The main battery bank is about 600 amps. (6 6 volt golf carts)

I am concerned that batteries are not getting charged sufficiently with voltages of 13.85. What I am proposing is to connect the output cables to the input and thus charge at 14.6...basically join the output to the input on both alternators as an interim measure. I understand that the strongest alternator may overcome the other one when they drop out of bulk. I have tried this on one of the alternators and it seems to work as thought with 14.XX volts showing on relatively full batteries. The only issue that comes up is that in the absence of the isolator there is battery voltage at the positive terminal of the alternator. Can this be/cause a problem? So far I have just tried this on one of the alternators.

My ultimate goal is to upgrade one of the alternators to 100+ amps with an external regulator but due to confined quarters can only fit a 5" or 6" max alt, which limits me to around 120 amps or less. I was thinking one of the Leece Neville MR series with a Balmar ARS5 regulators. It would be nice to use one of the new Balmar 6 series alts, but with the regulator I'd be on the wrong side of $1000. with tax. Any alternative suggestions would be welcome.

This seems like a very complex boat, electrically, with automatic relays and automatic transfer switches with very cramped access. I just had to replace the Xantrex Freedom 2000 inverter/charger with a Magnum ME2125 and remote because the Xantrex gave up the ghost.

Ian Munro
M/V Odyssea
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