cheflee

Here's the background. I have a dual battery setup with solenoid isolator and two yellow top optimas, all of which was installed in October 2009. This past weekend I went to start my Jeep and the radio went blank and it clicked very slowly at about 3 second intervals. The first thing I do is a quick search on this forum and then start working through solutions.

Pulled the M13 fuse, disconnected the battery, let it set, tried to restart it and every possible variation of combinations of these...nothing.

So I used the solenoid to jump start it and started right up. Checked the alternator while it's running...14.6v. Alternator is good.

Next morning dead again. Check both batteries and primary is at 9.6v and aux is at 12.7v. So I figure must be something draining the battery that low. Again jump it with the solenoid and when I get home I disconnect the primary battery to see if it holds the charge.

Next morning primary is at 12.7v and aux is also at 12.7v. First thought is something's draining it. Hook up the cables and it won't turn over, but starts just fine again with the aux battery jump...again.

Here's the questions...is it possible for the battery to have full voltage and not have enough power to start? (I'm not good with electricity) In which case replacing the battery corrects the issue? Could it be caused by something else and what would I need to look for?

I'd appreciate any help or opinions.

Thanks.

captjay

First off, make sure all terminals and posts are clean.

Have you switched out the batteries? As in, the battery that is low, take it out of loop and secondary now becomes your primary. See if the problem happens again. If it happens again, then something is draining it down over night. If it does not happen, then your original primary is probably bad and needs replacing. Just because the battery is not that old does not mean it can't go bad. I think they only have 24-36 month warranty.

I would have Sears, Wallmart, or a reputable auto parts store load test the battery to see if it is any good. Just because you have good voltage does not mean that you have enough cranking amps.

JK-Ford

Yes. Batterys have to be load tested.

You have already proven this issue with the battery isolater. The charging system is working, keeping the second battery full.