charging batteries in parallel

[mercforever]

bought an extra deep cell batteries for my 12 v trolling motor,hooked them up in parallel,just wondering if i charge them separately(which would be a pain)or can i charge them hooked up as they are.secondly is there anything i can measure with a multimeter that tells me theyre fully charged.i have an automatic shutoff charger i bougt from crappy tire last year and now im starting to doubt it.i borrowed my neighbors charger(better one than mine) been charging for a while and theyre still not fully charged.What the f am i doing wrong???sadly im an electrician but dc is not my thing............

[danbouck]

I believe if you charge them in parallel as soon as one is charged, the charger will shut off leaving the other one low. The best thing to get is a battery load tester.

[danbouck]

The tester

 

http://www.princessauto.com/shop-garage/re...=battery+tester

[Stoty]

What if he hooks them up in a 24V manner? (junk of one to neg of the other)

Will they both charge, or just the one?

[POLLIWOGG]

Go back to ctc and get, I think its called a specific gravity tester, looks like an antifreeze tester or turkey baster. You draw up some of the fluid from the battery and a weighted gauge floating in the fluid tells you the condition of each cell. It wont lie to you and its cheap.

 

the acid you spill on you will make your jeans look cool for a day or two before they fall apart.

[Terry]

if they are hooked up in parallel, hooking the charger to the one battery will charge them both

of course it will take twice as long

[Fisherman]

if they are hooked up in parallel, hooking the charger to the one battery will charge them both

of course it will take twice as long

That's true if the both batteries are reasoanbly close to being able to accept the same amount of charge, internal resisance, age, plate porosity, all come into play. Although it might be a bit of a pain, individual charging will give better results unless you are using a multi bank charger specifically intended for that. As for Stotys 24V try, please don't play with batteries, you might launch one and injure yourself. Most chargers, even the junk kind won't put out more than 15V DC, so you're kinda peeing up the rope.

[danbouck]

What if he hooks them up in a 24V manner? (junk of one to neg of the other)

Will they both charge, or just the one?

 

You can buy a 24V charger for that. Don't charge them hooked in series with a 12v charger

[scugpg]

I run a 24V setup however use two of these to charge my Optimas separately:

 

http://www.canadiantire.ca/AST/browse/4/Au...y%2BCharger.jsp

 

Best chargers on the market and have a ton of safety protection on them...plus you can leave them plugged in for months as they have a trickle mode. Come with little connectors so you can just plug n play when you need a charge.

 

If you charge them both at once you run the risk of cooking both batteries if one is bad. I'd charge separate for the little extra time/money to save your batteries and be safer.

[Sinker]

I charge mine separatly. I just pop the one cable off the positives and charge one at a time. If I leave them attached I find I don't get as good a charge for whatever reason.

 

S.

[dim.]

Batteries in parallel in general is not a good idea. Especially when it comes to charging.

Google "dual battery isolator" it would cost you 50-60$