Adding Another Battery ?

[gramos]

I just bought 2 new 86 a/h batteries as 1 of a pair had failed . while waiting for the new ones I used a spare 55 a/h battery all was fine . now that I have a spare 55/ah battery I wonder if it could be used as in addition to the bank ? a bit more battery power is always good ?

[CharlieJ]

In general, as long as the batteries in the bank are the same chemistry and similar in service life, then there is no problem.

In other words, if your spare battery has been lightly used, and not abused (read sulphated) then, no problem. If, on the other hand, your spare battery has been flailed, beat up, and generally abused during its lifetime, it would not be a good idea to add it to a bank of new batteries.

Charlie

[Ex-Calif]

Yes - Different a/h ratings is OK.

While you are at it consider a 1-2-both switch and put the 55 a/h on as a the "start" battery and the 86's as the house.

We generally run our 3-battery system in the "all" mode but when we know we will be laid up for a weekend somewhere I switch to "2" (2 batterys) and know that even if we drain the house we will be able to start the donk in position 1.