Hi all, 1991 Explorer 4x4 XLT. Just got it a month ago. It *Usually* starts up fine in the morning but if I leave it for more then a day, w/o starting it, it won't turn over. I have to jump it. Ok, so battery is bad right? Nope... Not according to the 2 places I took it to get a new battery. They told be don't replace it, as its fine.

So .... something is draining the batter but what??? Hood light goes off, interior lights are off... hmm. Any special tricks to try to see whats draining this sucker?

Thanks,
Steve

Your alternater might be bad. I don't know.

if you have and amp and not hook up right ,or radio that will drain power

I had a battery test "good" under a load test. After a few months it finally tested bad, but that was after verifying no parasitic drains. Here's what you do. Take off the positive battery cable and connect an ampmeter in series with it. With the key off, there should only be at most a hundred or so mA (to run radio and computer memories). If it's more, then start unplugging fuses in the power distribution box. If the draw remains the same, then it isn't in that circuit, move on to the next fuse. When the draw drops off, then you've isolated the circuit that is causing your problem.
Perhaps the first circuit to test is the fuel pump circuit. The fuel pump relay is known to get stuck "on" draining the battery through the fuel pump.