Can I trickle charge two batteries with one charger?

I have two similar, if not identical batteries, hooked together with an A-B-Both switch.

Can I put a small jumper from positive to positive, negative to negative, and put the trickle charger on the batteries to "tend" both simultaneously? For recharging and/or winter upkeep?

 

If they are connected with an A-B switch, just put it on " both " and charge away!

 

Trying to isolate it from the other electronics.

Should I double it up to 4A, or leave it on 2A?

 

I've done it many times but the trick is that the batterys have to be about the same size. You can't charge a scooter battery with a car battery. I have a couple of 50 cc scooters and I always tandam thems.

 

When the second battery died, I tried to get a new one that was as close as possible to the same size as the old one.

I am pretty sure I ended up getting the exact same battery. This is on my boat, and they are the same brand, and the same CCA, I think. I wanted to keep them similar just in case.

But one is a year newer.

 

Do it !

 

Will do!

Going to find a chunk of #8 wire or similar in the attic, cut it in half, and put clamps on each end!

 

12 or 14 is plenty, you only using an amp and a half. What size is the wire coming from the charger ?

 

Not sure, it feels like stranded lamp cord, if not smaller. Might be able to take an old chunk of lamp cord or extension cord and make a 24" jumper.

 

Can't be much different than my 71 Grabber. It has 2 batteries. I turn the swich and isolate the rest of the car from the battery, then charge both batteries at the same time.

 

Sounds like a safe deal, then!

I just gotta make up the jumper cable.

 

Why are u jumpering the terminals when you can simply put your switch in the both position? 4amps or 2 doesn't matter. That ur charger is automatic and stops charging does.

 

On boats, there is often something pulling a drain from the battery, causing you to come back to dead ones. Radio, maybe forgot to turn off the depthfinder or fishfinder, etc. So, it is just a safer bet to turn the kill switch on and not have to worry that I may have something draining on the battery(ies).

Just peace of mind...

Yes, easier to just turn switch to A+B, but if I left something else on, I may come back to 2 dead batteries, and a burned out charger and other item(s).

 

Close....Boats have permanenty installed hard wired chargers that are always left on. Right now, my boat has its 12v 5 amp refigerator running. My 50.amp charger covers the load,up to its rating. The batteries do nothing. If my boat springs a leak the 12v bilge pump runs from the charger not the batteries. A modern charger, such as Guest brand, will charge, then stop charging and then maintain the batteries without overcharging them. Batteries lastlonger when maintained in this manner. When this superior battery maintenance is applied to cars, it is the same...get a marine chrger from a West Marine store..and an extension cord.....parallel your batteries and walk away with peace of mind. I'm on vacation in vegas and my boat is in marina del rey.... I have guest 6 amp charger on my coronet in my garage...plugged in and maintaining...not charging

 

Um, not that kind of boat.

This is a small ski boat, put up in a storage shed for the season. I may yank it out at any time, to take it out, if the weather straightens up.

This isn't a boat sitting in a harbor, being "used" all the time.