Charging dual batteries in parallel (1 Viewer)

[RiverRatMatt]

Not exactly cruiser related, but at work we use a 14 foot alumacraft boat with a 20 horse Yamaha, electrical start, and an alternator. We have a smaller, secondary battery that we use to pump chemicals for pond/lake treatments. Would we be able to connect the two batteries in parallel to charge both, or do we need a charge controller due to the different size of the batteries?

 

[Greg_B]

Charge controller would be the cleanest way.

Couple of good threads to read: IBS-DBS: Interesting malfunction and solution and Dual battery systems; making sense of the options both have good info and links to videos that are informative.

hth's
gb

 

[george_tlc]

I'd imagine the alternator on the yamaha is fairly anemic versus an 80+ Amp vehicle alternator. Since batteries are constant voltage charged with current limit, I'd suggest you verify the alternator output rating and then see if it is less than your small battery's maximum charge current. If it is, you're good to go for parallel charging.

cheers,
george.

 

[RiverRatMatt]

Thank you both, I'll look into what you've mentioned!