Battery isolator -- Passage 42

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Grant McLaren

I recently had the factory battery isolator of my 1990 Passage 42 disconnected and bypassed with results have been nothing short of dramatic. Previously, my start battery had always been well charged but the house battery bank (2 x AGM 255 amp hrs each) never would charge very fast or to full potential. I suspect that the isolator was favoring the start battery and limiting the bulk charge to the house bank. WIth the original factory isolator bypassed my bulk charge rate, from shore power, genset and alternator, has imporved better than 50% and the house bank is, for the first time, getting up to its full potential charge. (Now, of course, I must now be carefull to turn the battery selector to 'house' at anchor so as not to discharge the start battery) Just thought this might be of interest to owners of Hunter models with factory battery isolators. My local marina electrics guy has been doing a brisk business letely in disconnecting Hunter isolators.
 

Rick D

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Jun 14, 2008
7,201
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Thanks Grant! Worth Looking Into!

nm
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Thanx, good reminder.

That is a reminder that I first saw posted some years ago. I have not had the same problem with the battery combiner. All of my charging sources are connected to the house bank. A combiner keeps the starter battery topped off. We never use any switch position except #2(house). The Link 2000 tells me if the starter battery is OK.
 
Apr 14, 2004
54
Hunter 28.5 Marinette, WI
Re: Battery Isolator

Is the factory isolator diode-based, or relay-based? Diode-based isolators have a voltage drop that can fool a charger into sensing the battery is fully charged when it really is not. If it is diode-based, then replace it with a relay-based unit (combiner). That'll allow you to not worry about switch settings and you get the full charge you're looking for across battery banks from a single charge source.
 
Dec 25, 2000
6,049
Hunter Passage 42 Shelter Bay, WA
Dave, does a label on the unit state whether...

it is relay based? Terry
 
Apr 14, 2004
54
Hunter 28.5 Marinette, WI
Re: Label

Not sure. However, if you can get any other info from the unit itself, such as brand, model, etc., we could probably do a little research and find out just what type of unit it is. Here's a suggestion that you can try to see if it's a relay type. Turn your key switch on and off and see if you can hear any clicking coming from it. It's a common method to use the key switch to activate the relay on a combiner. That's not to say your boat is set up that way, but it's worth a try. If it's silent, then it's a diode isolator or it's a combiner that's energized from something other than the key switch. Diode isolators are non-mechanical (electronic) and are always "active". They are one-way electronic "gates" that allow voltage/current to flow in only one direction. They will make no noise at all. Combiners are typically electro-mechanical and require a small amount of current to close the relay contacts. You should be able to hear clicking when they activate and deactivate. "Dumb" combiners rely on some external mechanism to activate it (such as key switch, oil pressure switch, etc.). Other combiners, like the West Marine unit, are "smart" enough to sense charging voltage (above 13.? volts) at the batteries and activate automatically.
 
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