Battery drain overnight? [Expired Topic]
Here's an intersting worry....
Recently, my suburban (99, 5.7, 2wd, 148k) would not start in the morning. A jump fired it right up and it would run and restart all day.
So - that night I checked for lights being left on, listened for anything running, made sure there wasn't anything plugged in to the cigarette ligter...
The next morning - same thing - battery too low to start.
I jumped it and again spend the day driving somewhat happily - but concerned.
I noticed that the voltage meter seemed to hang around 13v. Never to 14 - always less.
After the 3rd day with it not starting in the morning, I got ticked off (and it was the weekend, so I could do something about it) and went and bought a new battery (figuring that the old one had a bad cell or something).
I noticed that it started right up and the voltage meter was showing 14+v of charge just after I started it and then it came down a bit to run just right at or just under 14. (As I would expect - recharge from the cranking draw until equalized..)
It's been a little over a week now, it's started every time since the replacement and I think it was just a bad battery and is now fixed, but.....
How would you guys troubleshoot an overnight voltage drain if you suspected one?
Tim the technojunkie
RE: Battery drain overnight?
disconnect the negative battery cable and connect an ammeter between the post and the cable. DO NOT open the doors or tailgate, as this will blow the fuse in your meter. you should also disconnect the underhood light. The service manual will give you specs on the correct amount of current draw, but it should be less than maybe 700 milliamps once the computer has gone to sleep. even that number is high, but a vehicle with many electrical accesories that have memory will draw possibly that much current when the vehicle is off. If the draw is high, start pulling fuses one at a time until your draw goes away, then get a schematic for that circuit and start tracing.