having the same problem (help)
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Track Day
Joined: May 2011
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From: University of California, Riverside
having the same problem (help)
So I'm having the same problem that I had before. The battery keeps dying completely even after I got a new alternator. It's been a week since I got the new alternator installed and yesterday while I was driving back home the car just died on me. Any idea what it might back or what's causing this?
-Parm
-Parm
RL Community Team
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From: San Francisco Area
We just solved the same problem on my brother's VW.
First, with the key off, disconnect the battery negative, and put an ammeter in series to connect the terminal to the battery. This will measure the minimum current draw. It should be less than 5mA. If it is, then maybe your battery is bad. If it's more, then continue. Note how high your current is, so if it's 15mA, you have 10mA to find.
Take out all your fuses and use the ammeter in the fuse sockets to see which one draws current. Hopefully you find it. If you don't, you need to disconnect your starter and alternator cables (which come directly from the battery) and put your meter in series to see if maybe one of these cables is grounding out. On my bro's VW, the alternator had an internal short, and it was drawing about 12mA with the car off.
An alternative to pulling all the fuses is to leave your ammeter connected at the battery (alligator clips?) and pull one fuse at a time, looking for a sudden drop in current draw.
Good luck!
First, with the key off, disconnect the battery negative, and put an ammeter in series to connect the terminal to the battery. This will measure the minimum current draw. It should be less than 5mA. If it is, then maybe your battery is bad. If it's more, then continue. Note how high your current is, so if it's 15mA, you have 10mA to find.
Take out all your fuses and use the ammeter in the fuse sockets to see which one draws current. Hopefully you find it. If you don't, you need to disconnect your starter and alternator cables (which come directly from the battery) and put your meter in series to see if maybe one of these cables is grounding out. On my bro's VW, the alternator had an internal short, and it was drawing about 12mA with the car off.
An alternative to pulling all the fuses is to leave your ammeter connected at the battery (alligator clips?) and pull one fuse at a time, looking for a sudden drop in current draw.
Good luck!
Last edited by FRporscheman; Sep 2, 2011 at 02:54 AM. Reason: added "at the battery"
Race Car
Joined: Nov 2001
Posts: 4,089
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From: $F Bay Area
We just solved the same problem on my brother's VW.
First, with the key off, disconnect the battery negative, and put an ammeter in series to connect the terminal to the battery. This will measure the minimum current draw. It should be less than 5mA. If it is, then maybe your battery is bad. If it's more, then continue. Note how high your current is, so if it's 15mA, you have 10mA to find.
Take out all your fuses and use the ammeter in the fuse sockets to see which one draws current. Hopefully you find it. If you don't, you need to disconnect your starter and alternator cables (which come directly from the battery) and put your meter in series to see if maybe one of these cables is grounding out. On my bro's VW, the alternator had an internal short, and it was drawing about 12mA with the car off.
An alternative to pulling all the fuses is to leave your ammeter connected (alligator clips?) and pull one fuse at a time, looking for a sudden drop in current draw.
Good luck!
First, with the key off, disconnect the battery negative, and put an ammeter in series to connect the terminal to the battery. This will measure the minimum current draw. It should be less than 5mA. If it is, then maybe your battery is bad. If it's more, then continue. Note how high your current is, so if it's 15mA, you have 10mA to find.
Take out all your fuses and use the ammeter in the fuse sockets to see which one draws current. Hopefully you find it. If you don't, you need to disconnect your starter and alternator cables (which come directly from the battery) and put your meter in series to see if maybe one of these cables is grounding out. On my bro's VW, the alternator had an internal short, and it was drawing about 12mA with the car off.
An alternative to pulling all the fuses is to leave your ammeter connected (alligator clips?) and pull one fuse at a time, looking for a sudden drop in current draw.
Good luck!
Instructor
Joined: Dec 2009
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The battery on my car kept dying a few years ago and it turned out to be the light under the hood not going off. The switch was getting stuck and when the hood closed it would not turn the light off. I cleaned the switch and everything works great.
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RL Community Team
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Thanks Trevor! 
968parm, I just reread my post and something was ambiguous - at the end, when I say leave your alligator clips connected, I meant to say connected between the battery negative and the car's negative cable. Good luck.
bbain, you just reminded me I had the same issue with one of my cars, and I guess mine was too far gone to fix with cleaning, so I just left it disconnected and taped up the wire which went to it. I have a bite-sized (
) LED flashlight in the console anyway so I can live without a hood lamp.
968parm, I just reread my post and something was ambiguous - at the end, when I say leave your alligator clips connected, I meant to say connected between the battery negative and the car's negative cable. Good luck.
bbain, you just reminded me I had the same issue with one of my cars, and I guess mine was too far gone to fix with cleaning, so I just left it disconnected and taped up the wire which went to it. I have a bite-sized (
) LED flashlight in the console anyway so I can live without a hood lamp.
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