'99 Sierra Battery Issue

My '99 GMC Sierra has been acting up lately. The battery is original, had it load tested and it checks out ok. If the truck sits for more than a day
than the battery is low or flat when I go to start. I verified the only accessory that is on is my cell phone plugged into cigarette outlet. Has anyone else experienced this? I am wondering whether it has something to do with the cell phone or whether it is some other issue....
Thanks, -Mike
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Mike Bittel wrote:

battery voltage comes up to about 14 volts when the engine is running.
If that is ok you will have to deterimine if there is leakage someplace. I would disconnect the battery lead (ground line is ok) and hook the meter in amps mode in between the battery and line. If you have anything more than a few milli-amperes of current you will need to try to isolate the problem.
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The battery is charging ~14volts while it's running.

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I would say that a 5 year old battery is always suspected. It ma test good after charging, but with a bad cell, it will go flat quickly. substitute a good battery and see if it is ok after setting. or put an ammeter in series with the battery treminal and see if there is a current bleed. john

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Five digital dollars says it's your alternator putting a draw on it when it's NOT running. Disconnect and let sit....or take an amperage reading with it plugged in and unplugged....
~KJ/TLGM

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Mike Bittel wrote:

I'd agree with "johnny". If the truck is charging properly and you have verified that you don't have some sort of draw (unplug the cell phone when you turn the truck off), then I'd go with a new battery no matter how it tests out. After 5 years, it's a bit of a crap shoot with any battery.
Ian
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AC Delco has a 6 year warranty.... generaly go for 10 around my household. (just a hint when buying your new batry)
~TLGM/KJ
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