Can I charge both batteries at the same time with jumpers ?

[Bumpus7]

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Can I connect my starting 12 volt battery, to my 12 volt trolling motor battery with a set of jumper cables, and charge both batteries at the same time while I cruse around in my pontoon boat, and travel very slowly running on a river that has a long no wake zone which I use in traveling to my up river fishing hole ?


bumpus
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[Splat]

Re: Can I charge both batteries at the same time with jumpers ?

Sure you can, but you'd be better off using a battery isolator. If you simply connect the two together the one with more charge will drain into the lesser charge until they equalize. A battery isolator will prevent this but allow both batteries to charge at the same time., but be disconnected when the engine is off.

Please understand also the alternator on your engine prolly won't put out enough to add any considerable charge to your deepcycle.

Bill

 

[Rip Tide]

Re: Can I charge both batteries at the same time with jumpers ?

I can't see why not, as long as they are both 12V. I would keep an eye on the trolling battery to make sure it doesn't get too warm and start to boil. I'm sure it is a much smaller battery with less Ah rating. I would probably fuse the + wire going to the trolling battery, just to be safe. Also remember that charging a battery produces Hydrogen gas, so connecting and disconnecting wires above a battery can have hazards. What about using a 12V power point like a cigarette lighter.
Just a thought, like you said, we all have them and some are better than others, you decide.

 

[Bumpus7]

Re: Can I charge both batteries at the same time with jumpers ?

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My dash board gauge say it is charging at 13.

Body wise my troll batt. is larger than my starting batt.

I know the crank amps will be different and both are 12 volt.

Trying to avoid taking out the troll to recharge at home.

Maybe I will get a heavy switch so I can change over to charge troll
when it is low and back to start batt. after it is done.

Both batts. sit side by side in a covered box.

If I ever run down the start batt. and it won't start motor
I'll just jump from the troll to get it started.

I appreciate the info ... God Bless you guys ! ! !


bumpus
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[Silvertip]

Re: Can I charge both batteries at the same time with jumpers ?

Trolling motor batteries are generally much higher capacity than the starting battery but that is not the issue. The issue is the capacity of the alternator on the engine. Most engines just poking along don't output very much current and that output is needed for the starting battery. If you run long distances at say 3000 rpm or higher, then yes, the jumper cable technique would add some extra run tiime. But be aware that a deep cycle trolling motor battery if deeply discharged, would take many hours of running wide open to fully charge it. So your scheme should be used only to extend run time for the troller, not to fully charge the battery as it won't happen. You need to fully charge the deep cycle battery on your return to the dock. An on-board smart charger is best for this if you have shore power.