Charging system

D

Dan Kozusko

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Joined
Oct 11, 2007
RO Number
28781
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108
My 89 Santego has the twin mercs i/o with separate alternators.I have two batteries hooked up to the isolator switch. I believe this a stock hook up.My question is, both batteries charge only when I select BOTH on the selector while underway.Otherwise only the selected battery will charge. With twin alternators, wouldn't each alternator charge one battery each? When I select one bank, do both alternators charge together? I haven't a schematic and tracing the wires would be mind boggling. When operating the vessel, is it then advisable to select BOTH when underway and return to a single bank when anchored? Any thoughts?
 
On my 3607 each engine charges its own battery. The battery switches are configured to allow you to combine if one battery dies. I'll try to get you the 12 v wiring diagram.
Jimmy
 
Whoops, I was wrong. Checke d mine and you are right, that is the factory setup.
 
My 30 ft carver aft cabin is the same. Can we re wire to make it charge both with out changing the switch.
 
I moved from a 30 Criusers to a Carver 356 and found that Carver seemed to miss the 'boat' on this matter. On our Carver, it is as you said, you only charge the battery that is selected, but if you are drawing any current (fridge, water pump etc.) you are also using that same battery. The battery not selected is just along for the ride, so to speak. If you require it to be charged because you drained it over night at anchor, then you would have to select 'both' to charge it. My Cruisers was completely seperate. Each engine took care of it's own 'engine' battery and each engine would charge the 'house' batteries. It seems most Carvers I have seen don't have a separate house bank, they do things differently. As far as I know, putting in isolators (not the manual type), would allow each engines alternator to charge the batteries.I hope this helps and that I have not lead you astray. Trevor
 
Thanx for the input. The question that baffles me is when under way with BOTH selected, does one alternator charge both or does each alternator do each battery separately? I can't see how both alternators can be on the same circuit at once as their regulators would combat each other. Any thoughts? Does one alternator only supply the power to run the engine only?
 
quote:
Originally posted by Dan Kozusko

Thanx for the input. The question that baffles me is when under way with BOTH selected, does one alternator charge both or does each alternator do each battery separately? I can't see how both alternators can be on the same circuit at once as their regulators would combat each other. Any thoughts? Does one alternator only supply the power to run the engine only?

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I don't have my manuals with me, but I seem to recall reading a warning that you should not have the switch in "both" while underway. I don't recall why, but the things you suggest make sense to me.
 
My understanding is that it is O.k. to leave the switch on "both". The recomendation is that you don't move the switch while underway. I think the concern is a power surge that could damage equipment. My boat charges all batteries if it is set on "both".
 
After thinking about this topic, one reason not to run with the switch on "both" could be that if something catastrophic happened to a battery or alternator, the problem potentially could damage the other side of the set up. If the system is isolated, the damage would just be on one side and allow you to get back to the dock under power.
 
I usually run with the selector set to both while underway, especially when travelling from anchorage to anchorage where the chance to charge from a dockside power source doesnt exist. It's the only way to ensure both batt banks get charged. Of course, once stopped it's important to remember to switch to 1 or 2. The one thing you should never do is turn the battery selector switch to the 'off' position while the engines are running as it can damage your alternator very quickly.
 
3 rules:
BOTH while underway is OK (so is 1 or 2).
Either 1 or 2 when on the hook to assure you don't run down BOTH batteries accidentally (backup).
NEVER run engines while switching OFF both batteries (damage).
 
Thanx for the input. Glad to know I can run with both selected. Now does anyone know if both alternators work together or are they separated somehow???
 
Not sure about your question but if your boat is equiped with an alternator on each motor they should function independantly. If you run on "both" you are combining charging systems to some extent. Some boats come with an alternator on only one motor. Not sure about your boat, my 3227 is set up so that each motor has it's own starter battery, alternator, voltage regulator, gas tank... If something goes wrong with one of systems, you still have one motor to get back to the dock.
 
32 carver. I do have two of each which is why I started this line of questions. I always assumed that each genny would charge its own battery, but I found this not to be the case. I would only charge both my batteries if I ran the selector on BOTH. This begs the question, what does one of the alternators do if the other one charges both through the selector?
 
You have to have an alternator on each engine otherwise you would be running the motor without the alternator off the battery if the other motor was not operable. I learned the hard way WRT the battery switch as Searay has the same setup. The alternator only charges the battery(s) selected on the switch. I usually set it to my starting battery(1) to start then switch to both while running and then to house battery(2) on the hook.
My 82 Carver 33 Mariner has 2 batteries and 2 engines and a 1/2/Both/Off switch. So you guys are telling me you think it to be the same arrangement, one starts both motors. It had two 8 year old Group 27 Deep Cycles, one OK the other dead, when I got her. I replaced with 1 group 27 starting and 1 group 31 deep cycle with the intention of adding a second group 31 for the house bank. I have it on my "to do" list to take a multi meter to this setup to confirm what does what.
Eddie
 
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