battery keeps dying

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=54960
Printed Date: May 13, 2025 at 7:57 AM

Topic: battery keeps dying

Posted By: supradude
Subject: battery keeps dying
Date Posted: May 02, 2005 at 7:17 AM

I need any advice I can get on this problem. I can charge the battery and hook it back up in my car, and the next day it will be dead again. I have been looking for possible wires that would drain the battery with no luck. What is the best way to find the source? It has to be something that is staying on, but I have looked high and low and can't find it. I have tried 2 different batteries and had mine tested.

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'85 Toy

Replies:

Posted By: thepencil
Date Posted: May 02, 2005 at 9:20 AM

What year and car is it? I bet it's a GM product!
Starter Kill relay. If you have it connected incorrectly. That can be one of the issue.

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Be careful whose advice you buy, but be patient with those who supply it. posted_image

Posted By: Satkunas
Date Posted: May 02, 2005 at 12:25 PM

Here's a tip to find the drain.

Get your hands on a regular bulb test light (not computer safe). Disconnect the negative terminal of the battery and insert the testlight in series from the cable to the battery post. As long as the bulb is lit there is a drain in the electrical system.

Keep in mind that the domelight will cause a drain so either disconnect the doorpins, or pull the domelight fuse if you need to test with the door open. A radio's memory wire will aslo pull current so disconnect the radio and any other components that you know will have a drain to remove them from the circuit.

Remove fuses until the bulb goes out. Once you remove a fuse and the bulb goes out you now know what circuit is causing the drain.

Posted By: supradude
Date Posted: May 02, 2005 at 4:03 PM

It is a 1985 Toyota Supra. I will try what you suggested and see what happens. If I disconnect the negative cable will it still be drawing current with just the positive cable connected?

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'85 Toy

Posted By: Satkunas
Date Posted: May 02, 2005 at 4:20 PM

No, you need a closed circuit in order for current to flow. If you remove the negative battery terminal no current is able to flow through the electrical system, hence why the test-light is inserted in series so it illuminates whenever there is a closed circuit.

Posted By: overworked2
Date Posted: May 03, 2005 at 5:11 AM

Instead of using a test light, use your DMM set to amperage/current in exactly the same way as the test light.

A standard car should pull no more then .5amps...even that is far to high. Anything higher and something is staying on. Do you have amplifiers in your car? I know I had trouble with my car and it's amp. They would switch off but still pull enough current in standby to drain the battery over the course of several days.

The other thought is if you do have a high powered stereo....If you drive for short distance with the stereo up loud, then there is a chance that it is draining power out quicker then the alternator can recharge the battery. or even driving long distances with the stereo loud, you will be constantly draining the battery faster then you can recharge, if thats the case, then you need the services og a High Output Alternator.

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Check all advice given with a meter

Posted By: NotoriousTCD
Date Posted: May 04, 2005 at 2:51 PM

i had a similar problem this week. my power door lock switch was bad and was causing a short.

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Posted By: Satkunas
Date Posted: May 04, 2005 at 4:30 PM

overworked2 wrote:

Instead of using a test light, use your DMM set to amperage/current in exactly the same way as the test light.

A DMM is good if you want an accurate reading of the current drain, but a real pain in the butt when you have to get up from under the dash and walk around the car everytime you pull a fuse or unplug a module (unless the DMM has an audible current indication). The test-light is much easier to use as it gives a visual indication of how much current is being drained and you can probably find the drain in about half the time it would take you with a DMM since you dont have to get up and poke your head under the hood everytime for a reading.