Date: Tue, 18 Mar 2003 00:29:15 GMT
From: John Davies <>
Subject: Re: 1989 has battery drain

On 17 Mar 2003 15:01:45 -0800, (Amy Young-Leith) wrote: >I few weeks ago I bought a 1989 900 (non-turbo). It's a POS with over >225k, but looks great and is fun to drive. I paid diddly for it so I >figured if I had to tinker with it... well, it would be a challenge. > >I seem to have a power short somewhere. The battery will be DEAD, and >it'll jump start just fine, and charge the battery up enough to start >again if you shut it off. But overnight, it drains back down to zilch. > >This happened once when I first got it... then didn't happen for a >while, and now is happening all the time. > >My first thought is to replace the battery, but a few people have said >that since it'll charge back up, they don't think that's it. It had a >new alternator on it about a year ago. > >The answer may be that I have to take it into a professional, but >that'll have to wait a while. Anything a handy but car-dumb person can >do to self diagnose? > >Amy First of all, the battery is probably junk. Locate an automotive battery charger, charge the battery at least overnight, then drive the car to a local shop and have them test the charging system and the battery. Usually they will do this for free in the hopes of selling you some new parts. You have no obligation to buy from them. They need to do a load test to see if the battery has adequate capacity, and they need to check the alternator to see if it is charging fully at idle. Either problem MUST be corrected before proceeding. It's pretty easy to determine if there is an abnormal drain - the problem is finding what exactly is causing the problem. The best way for you to at least isolate the cause is to buy an inexpensive digital voltmeter at an auto parts store. Get one that has an ammeter function of at least 1 amp. 10 amps would be better (and more costly). Charge the battery and remove the negative (black) battery cable. Set the meter selector dial to amps (current reading) and connect the black meter wire to the disconnected battery cable, and touch the red meter wire to the negative post on the battery. With this configuration the meter will show how much current is flowing through the battery. With the ignition key OFF, there should be no more than 0.1 or 0.2 amps. Any more than that and you have a serious drain. You can start pulling fuses one at a time, and replacing them, until the abnormal drain goes away, and that will tell you the circuit that has the problem. In addition to a meter, you really need a good electrical diagram. Once you figure out which circuit is bad, you can check out the components on that circuit and hopefully locate the culprit. Good luck - this sort of electrical problem can be frustrating to solve. Don't hesitate to ask again in this group, or ask a friend with electrical knowledge to help you. My suspicion is that if you replace the battery everything will be fine. John Davies Monroe WA USA 2001 Saab 9-5 Aero Wagon 2000 Audi A4 quattro 1.8T 1991 Jeep Cherokee Laredo 4x4

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