Connecting Multiple Batteries

[howson]

Is load testing (the type they usually do at automotive stores) really a good idea on deep cycle lead acid batteries? As opposed to automotive batteries where a large current surge is needed to provide starting capabilities, RV batteries just need to provide a stream of relatively low current.

Wouldn't it be less harsh or damaging to charge the RV battery and then after a resting period check the voltage or specific gravity of the acid?

Yikes...there's a ton of links on the internet when I searched for "load test a deep cycle battery". I can't vouch for any of the references, so I'll leave a definitive answer to others.

[Lonestar]

howson

Maybe like other subjects and not have any one answer. I don't have a clue.

I had 3 year old battery in a Toyota that was load tested on a service appointment, and cratered the next day. I don't let them do that anymore.

I didn't mean to hijack this thread, but it was suggested in one of the posts.

[Cate&Rob]

A deep cycle lead/acid battery should be easily able to handle a 100A load for about 10 seconds without significant voltage drop. If it can't, it needs to be replaced. You don't need to take the battery to a store to have them do what you can do yourself with an inexpensive load testing meter. The scale on the meter shows voltage drop with applied load and the scale is colour coded for what is good and what is not. The load is a resistive element, so this thing is basically a 12V toaster . . . it is going to get hot . . . something to remember when using it.

As background . . . I used to have a boat with a bank of six deep cycle 12V lead/acid batteries. One bad battery would cause the rest to discharge or the battery charger to over-charge the good batteries trying to charge the bad battery. Eventually, I put a switch on each battery feed. If things didn't seem right, I would turn off all the switches and load test each battery. This very quickly identified the faulty battery. I use a similar logic on the RV with two batteries and a 1/2/Both/Off switch.

BTW . . . none of this applies to the original question because the OP does not have lead/acid batteries.

Rob