Optima Battery Question

[ILYA]

ok, so I had a little accident today... I have 2 brand new Optima D34M Blue-Top Marine Batteries which were connected in parallel in my van... As you may know, they have regular car (SAE) top-posts right next to a set of (5/16" stud) screw-posts... While working on it today, an aluminum box lid (connected to common ground) fell on top of the positive screw-on post on one of the batteries... I noticed within seconds, but by then the post was already glowing bright red and managed to weld the wing-nut to itself... I was able to take the wing-nut off with pliers pretty easily, yet there is a slight but noticeable damage near the bottom of the screw-post's base...

I just took both batteries to Autozone to get tested, the one that didn't get hit tested "good" all around... the one that took the hit tested "good" on the SAE top-posts, but tested "bad" on the screw-posts... I first thought that maybe a connection plate between the 2 sets of posts got fried, but both sets of posts output normal voltage though, so I am puzzled...

how is that possible??? is it safe to keep using the battery that took the hit by connecting only to the top posts, since they tested "good"??? is it going to take out my other battery if I reconnect them together again??? any ideas are appreciated, thanks in advance...

[rbrowning]

"but both sets of posts output normal voltage"

This can be somewhat misleading. ANY amount of connection will show you with the correct voltage as long as you are not trying to conduct very much flow, and your volt meter is a very high resistance load with minimal current flow. I am guessing that the Autozone test included a load draw and the top posts have a poor connection inside. I was caught by this once when one strand of a copper wire was sticking out from a terminal and touching another at a limit switch. It provided enough current to turn on an indicator light but not enough to pull in a solenoid.

If you put a set of headlights across the batteries, I bet you will find that the good battery maintains its proper voltage and the suspect one has a lower voltage and the terminal may get hot.

I would suggest that you switch over to the other set of connectors.