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Battery drains while car is running! Holds charge when off. Drops when car runs?!

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Old 08-06-2011, 09:55 PM   #1
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Battery drains while car is running! Holds charge when off. Drops when car runs?!

Hey guys im new to this forum and am new to Trans Am's (not a big chevy/GM guy) any way, I have gone through 3 alternators and have checked and replaced almost EVERY single ground. I have jumped the alternator sensing thing so it will charge at less than 3 grand (which is stupid that they did that) i have checked all the fuses under the steering column and they are good (including fan fuse) i bought the car a few weeks ago and when i bought it the previous owner rewired the fan so it turns on when the ignition is turned on. idk why though. There is a loose black wire (that i taped) that is connected to a fusable link. Almost positive that is the old fan wire so it turned on when it sensed the engine was getting too hot. WHen it has a fully charged battery (13 Volts give or take) and i start it it drops almost a volt (around 11.5) and when i rev it it drops even more. now eventualy it dies. i now know the car runs bad at times because this messes with the ecu when voltage drops low. The voltage meter does not go past the dashed mark region. Im wondering if this meter doesnt work and it is inline with the alternator and its broken, could this cause it to not charge? idk. but im running out of options so any help would be greatly appreciated! thanks -Robert 305 TPI (also new Battery) sorry thread is so long
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Old 08-07-2011, 12:25 AM   #2
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Re: Battery drains while car is running! Holds charge when off. Drops when car runs?!

Year model always helps when asking questions; one size does not fit all?

Originally Posted by ThatTransAmGuy View Post
Battery drains while car is running!
Obviouslybecause power is being used up operating the engine but none being replaced from Alt .Do the 3 Alts actually work ?

Have you put a DVM on the Alt terminals when engine running to see if Alt is actually putting out voltage????

Until you confirm power output from Alt; wasting your time chasing wiring problems
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