Batt dies when driving

65driver289 · Feb 11, 2009

My car has sat for the first part of the winter. last week I went to start it and the batt was completely dead. it was so dead my tricle charger would not charge it. I jumped it with my truck then hoked up the trickle charger. a few hours later I toke it out to get some dinner. came home from dinner and my headlight went almost black by te time I got home. I charged it up over night and but a mult-meter on it. when running it read over 14 amps. I checked it with the lights, wippers, radio and every other power drain on. it still ran over 14 amps. I ordered a volt meter gage to put in the car this weekend. dose anyone know why it would charge fine at idle but then drain the batt when I'm driving?
Thanks

rbohm · Feb 11, 2009

65driver289 said:
My car has sat for the first part of the winter. last week I went to start it and the batt was completely dead. it was so dead my tricle charger would not charge it. I jumped it with my truck then hoked up the trickle charger. a few hours later I toke it out to get some dinner. came home from dinner and my headlight went almost black by te time I got home. I charged it up over night and but a mult-meter on it. when running it read over 14 amps. I checked it with the lights, wippers, radio and every other power drain on. it still ran over 14 amps. I ordered a volt meter gage to put in the car this weekend. dose anyone know why it would charge fine at idle but then drain the batt when I'm driving?
Thanks

14 amps at idle? is that all? how much output at speed? its quite possible that your alternator is making voltage, but not enough amperage to charge the battery or even run the car. pull the alternator and have it tested. i think you will find it is indeed bad. i think if you test the battery also it will also end up being bad.

zookeeper · Feb 11, 2009

Sounds like the battery is gone to me. Once batteries go dead for an extended period, they rarely come back to life, no matter how long you charge them.

TOM B · Feb 11, 2009

Or do you mean 14 VOLTS
Early stangs have a poor charging system to todays standards.
I think the output was only 60 amps max and the external regulator was a joke.
I had a few stangs that the higher I reved the engine the less amps it put out When it was working right you could see the headlights go dim at idle.
I bought a powermaster alternator 100 amp ,internal regulator one wire hookup and had no problems now for 5 years and yes there made to be a direct fit.

2nd Mustang · Feb 12, 2009

Trickle chargers are meant to be used over a period of days, not hours. I have a small four amp charger (not a trickle charger) that needs on the average about 8 hours to charge a battery. Maybe the fan belt is slipping while you drive causing the drain on the battery.

I use a stock alternator and external regulator and it will handle the MSD box and halogen headlights with no problems. The stock alternator will consistently put out 14 volts with the headlights on.

If you decide to upgrade to a more powerful alternator, make sure your wiring in the car is up to the increased output. Good luck.

65driver289 · Feb 12, 2009

thank felas, I am going to work on it sat when the wife and kids are gone.

Batt dies when driving

65driver289

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rbohm

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TOM B

2nd Mustang

65driver289

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Batt dies when driving

65driver289

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