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1999 GMC Suburban 1500 Question: Battery Draining Too Fast



rbuckspan, Austin, TX, May 27, 2010, 11:48

Over the past year, my Suburban periodically had starting problems (would start, or not, or act like a weak battery). I replaced the battery and the cable ends and all was well for a few months. I drove across the country for 2 days - no problem. Then it started again. It was slowing with each start, and finally was dead and would not even jump start, so I had it towed. They looked at it and did a complete tune-up (said there was cross-firing etc) and it was fine for about six weeks or so. Now, it has slowly been giving me trouble starting, each day becoming a bit harder like the battery was dying - and it did. I had it checked - 10.3V - I charged the battery and all was well for four days, then it started acting as it did the prior two weeks. I put the charger on and after an hour, the battery was up to 12.3V. I started the engine and while running, the voltage is 14.2V. So, it looks like the battery is getting juice to re-charge while running, but it loses charge overnight and does not fully re-charge during the day - finally not being charged enough to start! I drive it ~20 minutes to and 20 minutes from work each day.

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  • Answer #1

    May 27, 2010, 18:47

    12.3 volts is WAY too low for an hour of charging. A new Battery should charge more than this after an hour on a good charger, it should read at least 12.9-13.1. 12.3 means that your battery is only about 1/2 charged. it also sounds like you may have a drain in your electrical system. First have your electrical system checked for a drain and if one is found you need to have it repaired. Then you can deal with the Battery. I would take that Battery back to who ever sold it to you and have them give you another new Battery.

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    rbuckspan, May 27, 2010, 19:29

    I measured the resting current with the engine stopped and nothing "on"
    It was over 50mA
    I removed each fuse to see what made a difference.
    Only when both BATT and LIGHTING (each 50A) in the engine fuse box under the hood were removed did the current drop at all - to zero. If either was in place, back up over 50mA.
    Not sure where the drain is?
    I'm keeping the two fuses out and fully charging the battery (it's at 25% by the charger!)
    Any other ideas for now?

    The vanity light switch was not turning the light off and the battery was bad (would not hold a charge). Fixing the switch and replacing the battery did the trick!!

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    Visitor, May 15, 2011, 15:14

    hank you this post was helpful

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