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Old 08-06-2014, 13:53   #13
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Z71bill's Avatar
Join Date: Feb 2007
Location: Texas
Posts: 12,810
Originally Posted by ERASER View Post
I had much the same problem. The car was fine if it was driven every day or so but the battery wouldn't crank the engine after a few days.
I took the + lead off of the battery and put a multimeter with a built-in ammeter on it between the battery and the now-removed cable. It showed that there was a high amp draw even though nothing but the "normal" equipment was on (i.e.: the constant power to the clock and the radio).
I kept pulling and replacing one fuse at a time until the amp draw dropped to well under 1 amp. It turned out that the factory radio amplifier kept pulling power even though the radio and the ignition switch were both OFF. This parasitic drain would kill the charge in the battery if the car wasn't started and driven every day or so to re-charge the draining battery.

A quick question: With a fully charged battery, if you disconnect the - cable and let the car sit for a few hours, would the battery lose it's charge?
After I jumped started it today and drove it over to Sam's Club (about 10 miles) the car would not restart.

So bad alternator is a possibility - but the idiot light does not light up - and the AutoZone alternator test was good.

I told my daughter (her car) I was 98% sure it was just a bad battery - but it is possible something else is wrong.
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