Battery not charging

Tiny
JASONEIME
  • MEMBER
  • 1997 FORD MUSTANG
  • 132,000 MILES
I took my battery and alternator to have it tested and they said that it was good. So I went to pull some fuses under my dash to see if I got a short somewhere. I went and pulled my radio fuse, as I checked the battery meter on the dash the meter dropped. I'm not sure what the problem with the wiring is because the fuse that I pulled goes along with the radio, lights, door locks, etc. Before all this my door locks would not stop locking and unlocking, so I pulled the cable off the battery terminal and it stopped. By the way the fuse I pulled was not blown. Can you help me? Can't afford to go to a dealer right now. Thanks
Sunday, June 9th, 2013 AT 10:41 PM

2 Replies

Tiny
CADIEMAN
  • MECHANIC
  • 3,544 POSTS
The locks are probably wear your problems at. Hook a volt meter or test light in between the native wire and the negative battery post. Then pull the courtesy light fuse so you can work with the doors open. Then pull the fuses until the voltage drops off or the light goes dim.
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Monday, June 10th, 2013 AT 1:16 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
The fact that the battery and alternator are okay means you have what is called a parasitic draw. That means something is staying on when it shouldn't.

Here is a guide on the common causes of this issue:

https://www.2carpros.com/articles/car-battery-dead-overnight

If none of this is the cause of the issue then we need need to do an actual ignition off draw test. The way to do this is unhook the negative battery cable and set you meter to amps. Then connect one lead to the cable and the other to the negative battery post. This will display the ignition off draw amperage. It should be around 20 milliamps or less. If it is more then you need to unhook fuses until it drops to this level. Once you remove the fuse that does this then that system is the issue.

At that point, hook the fuse back in and remove the actual components. So for example, you remove the radio fuse and the voltage meter drops, then you find everything that is on that fuse and unhook them one at a time until it drops. Then you know the specific component that is not shutting off. We can help with this point once we know what fuse it is. However, using the battery gauge on the dash is not a proper way of doing it and will lead you down the wrong path.

Please let me know if you have questions. Thanks
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Monday, April 20th, 2020 AT 4:57 PM

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