I have a 2007 toyota corolla s, today it started acting weird. It would click like the battery is completely dead, then start slowly cranking, then finally it would speed up and turn over. It happened 3 times today. Anybody know what might be the issue?
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That drove me nuts the first time I saw it in one of my own cars. The battery has a cracked internal connection, usually at the positive post. When you hold the key in the "start" position it drags a little current through it, fusing a small spot in the connection, and as the starter draws more current the fused area gets larger until it is back to nearly normal. Really weird. If you whack the positive post with a hammer, like cracking a hard nut, it will often behave normally.
The real test for that is to measure the battery voltage at the posts with the headlights on. If you see something like 10V and slowly rising, you know it is a cracked internal connection. It seems to be mostly a hot climate thing - about half the batteries I had in Phoenix died that way.