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Date: Tue, 10 Aug 1999 20:02:53 -0600
From: Paul Hahn <>
To: Mformation <> Subject: Re: Battery won't take a charge,

in Mformation #246, Danial Smith wrote :

"I didn't turn over my M6 for a month. When I recently tried, all I could get was some check lights. A few days later, everything is drained. The car is new to me (2 months or so), and I am aware of some past electrical probs. It has a pretty new battery (1/99). The car also has a clifford alarm."

If an auto battery goes down below a level of about 10v for an extended period ( hours , not minutes) all sorts of undesirable chemistry takes place in the cells and the end result is a coating on the plates that presents a high impedence to current flow so the cells can't conduct electricity very well , either as an output (power to you car) or an input (charging current). There are deep cycle batteries that tolerate existing at a discharged state better than others, but no battery is helped by prolonged draining of current.

There is some inconspicuous load connected to your battery that is sucking the life out of it. Possible causes include glove box or trunk light being lit all the time. Maybe you have an after market alarm system on the fritz or an electric heater on the locks or windshield washer nozzles. Connect an ammeter between the negative terminal of the battery and chassis ground and then remove the ground strap that normally grounds the battery. Be sure all accessories are off and all doors are closed. Don't try to run anything at this point or you might ruin the ammeter. unplug the trunklight bulb.

At this point you should see no more than 70 milliamps of current. That is .070 amps or seven one hundredths of an amp. you probably have over 100 milliamps and you need to find out what is on that should be off and fix it.

If you can't see it , try removing one fuse , read the meter and see if the current level has dropped to normal. if it has , now you know which circuit is the culprit. If not , then return the fuse and try the next fuse. Repeat the process until you figure out the extra load.


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