Two deep cycle batteries for 12V motor.

[halas]

Is it a common practice to have 2 deep cycle batteries connected in parallel to create a longer lasting 12V power supply for a trolling motor?
Can one use a one bank onboard charger to charge the parallel setup?
Will it ruin the charger due to smaller resistance? This is an all electric boat so there is no charging from any engines.
Hope someone done this and can advice me, thanks.

 

[Dunaruna]

Re: Two deep cycle batteries for 12V motor.

Is it a common practice to have 2 deep cycle batteries connected in parallel to create a longer lasting 12V power supply for a trolling motor?
Can one use a one bank onboard charger to charge the parallel setup?
Will it ruin the charger due to smaller resistance? This is an all electric boat so there is no charging from any engines.
Hope someone done this and can advice me, thanks.

Yes.

Yes,

No.

 

[Silvertip]

Re: Two deep cycle batteries for 12V motor.

If you have an on-board smart charger and it is plugged in when the boat is at the dock then you can forget what I'm about to suggest.

If the boat sits for long periods of time between use, I'd suggest you put a battery disconnect switch between the two batteries to break the parallel connection on the positive terminals. Two batteries in parallel rarely have identical characteristics and one will always be in a little better condition than the other. The idea here is to prevent the weaker battery from draining the better one until both are equal. This is a minor point but unless both batteries were purchased at the same time, this can be an issue.

You can parallel connect any number of 12 volt batteries. You would obviously need to upsize the charger as batteries were added but there is no theoretical limit to the number you could have -- short of sinking the boat of course.