Battery drain??

B

Bruno

Member
Is there an easy or simple way to check to see if there is a slight electrical drain on battery? If everything is turned off, is there a way to check for a "short"?
 
6 volt or 12 volt?, pull one of the battery cables off and put a 6v bulb between the batt post and cable, if it lights or glows you have a drain somewhere.
To trouble shoot unhook circuits one at a time until you find it. I bought a new Camero in '69 it took the dealership 8 hours to find a short, it was inside the trunk near the wheel well, so be patient and methodical.
 
Take off one of the battery terminals and check between it and the battery with a meter to see if there is any current flow (amps). If the battery drain is slight it should be a small amperage reading, so you would need a meter that is capable of reading amperage at various levels. Start at a high level, say above 30 amps, just to protect the meter and work your way down. Could also rig up a test light between a removed battery terminal and a battery post. If the current loss is enough, it would light the lamp.
 
If you don't have a meter, just pull off the negative cable (assuming positive ground), and then move it slowly back to the terminal without touching it. If you see a spark when it almost touches, there is a drain.
 
4dFord/SC said:
If you don't have a meter, just pull off the negative cable (assuming positive ground), and then move it slowly back to the terminal without touching it. If you see a spark when it almost touches, there is a drain.
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This IS the easiest way...it works! DD
 
Just make sure there is no hydrogen gas present when generating the spark. If the other end of the grounding strap is accessible, that will work also.
 
It doesn't take much drain to kill a battery. In a seldom used vehicle, an electric clock will do it if the fuse isn't pulled. The best defense is a battery cutoff switch. On old cars, putting a bulb or voltmeter between the cable and the battery will show a "parasitic" loss, and you have to disconnect portions of the system until it is found. We can't do that on newer cars because the battery keeps the ECM (engine computer) alive at all times. We recently had a Cadillac Escalade come into our shop. The battery would go dead in a couple of days. The dealer had replaced the battery and the alternator to no avail, and sent it to us. After considerable head scratching, and some luck, we found that the dimming circuit in the far back dome light wasn't fully releasing, even after the bulb stopped shining. If we hadn't seen it before we, too, would have been stumped.
 
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