Wiring Batteries in Parallel

[FinnessEm]

I'm new to this site so maybe this question has been asked before.
I'm going to run my batteries in parallel, is there a general rule as to how far apart
the batteries need to be. I'd like to spread them apart for weight distribution.
Thanks.

 

[OldFloater]

i am pretty sure that it wouldn't matter how far you have them apart since the space is limited to the size of the boat.

 

[JMichael]

You need to be sure the cables that connect the 2 batteries is large enough and you need 2 batteries and the same relative condition. It's best if they are the same as far as age and amphour rating. If one battery takes a better charge than the other, it's going to be constantly trying to charge the weaker battery as soon as you connect them. example: If you have one battery that will charge up to 13.4 volts and another that will only charge up to and hold at 12.2, the weaker one will start to drag the good one down to it's level as soon as you disconnect the charger. That's going to shorten the life of your good battery.

 

[FinnessEm]

I didn't think it would be a big deal.
Thanks for the info.

 

[kofkorn]

Only thing I would be careful of is the length and gauge of the wires between the batteries. Traditionally, there is usually a very short (less than 1') distance between the batteries with a pretty heavy wire, which is cheap at that distance. This results in a relatively small voltage drop across the 1' jumper.

With a long run (15ft??) between the batteries, you'll have a much larger voltage drop (2-3 Volts). This will cause a much heavier draw on the battery that is closer to the electric motor, and will probably cause you to have a shorter overall life on that battery. I would keep a good eye on the voltage level of each battery to make sure you don't over discharge one of them routinely.

To prevent that, I would up-size the wire gauge between the batteries as much as I could afford. It will probably pay off in battery life in the long run.

Good luck!

 

[FinnessEm]

Great info, Thanks.
The 2 batteries would be no more than 4ft apart. I'm thinking
6 or 8 gauge to connect the batteries.

 

[kofkorn]

With 4' and 6-8ga, you should be fine.

Good luck!