charging system
#1
charging system
when the headlights are turned on the amp gauge starts to fall from around 12.5 down around 8 I replaced the battery and the alternator sill draining the battery took the alternator back thinking it could be bad still having the problem. what could be draining the battery when the headlights are turned on?
#2
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Join Date: Dec 2016
Location: Sebastian FL
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Car: 87 firebird 86 c10 90 mustang
Engine: 383 sbc
Transmission: 97 t56
Axle/Gears: Moser 12 bolt 3.73
Re: charging system
Are you using a volt meter or looking at the volt gauge in the dash? Do you have under drive pulleys?
#3
Re: charging system
I used a volt meter just to check the state of the battery, I didn't change anything other than a new battery, and the alternator. I know that if i drive the car with the lights on it will kill the battery.
#4
Supreme Member
Re: charging system
post what volt readings you got from your DVM.
battery with everything off=
battery with car running=
battery with car running and headlights on=
battery with everything off=
battery with car running=
battery with car running and headlights on=
#5
Supreme Member
Re: charging system
you should perform a voltage drop test also. directions in this link;
http://forums.hotrod.com/circle-trac...your-race-car/
http://forums.hotrod.com/circle-trac...your-race-car/
#7
Supreme Member
Re: charging system
all low numbers. fully charged battery at rest should be around 12.6. it sounds like your alternator might not be charging. try hooking up your DVM from negative battery post, to the positive battery terminal on the alternator. sound be around 13.5-14.7 if the alternator is charging. sometimes those 10 gauge wires from the back of the alternator to battery positive post go bad. its ok to add a 2nd 10 gauge wire if needed. just need to verify that the alternator is charging at that post.
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#8
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Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: charging system
What year is the car?
When you turn the key to On with the engine not running, does the Alt light come on? (might be labeled "Choke" instead of something electrical)
When you turn the key to On with the engine not running, does the Alt light come on? (might be labeled "Choke" instead of something electrical)
#9
Re: charging system
went out today , was going to try and test the problem more dead battery. so what is draining the battery. new napa battery new alternator from napa.
#10
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Location: Sebastian FL
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Car: 87 firebird 86 c10 90 mustang
Engine: 383 sbc
Transmission: 97 t56
Axle/Gears: Moser 12 bolt 3.73
Re: charging system
It should have a little red battery that lights up on the dash. If it's out it may not complete a circuit the alt is looking for to start charging.