Battery keeps dying.

[Wobbles1971]

Im back to messing around on the Z after taking a leave for a bit. New home and kid have swayed me far away from the luxury of wrenching anytime I want. Starting back on the car now tho. One thing I cant figure out is why my battery keeps loosing charge. Only thing I could really think of, and is on my mind, is the horn button pad from my aftermarket wheel, the little pressure extension on the backside of the attachment is not touching, I need to bend it out more I guess. This is from the GT wheel motorsport Z sells. Anyhow, dont see how that would drain my battery so fast if at all. I loose charge every couple days and Im kind of lost atm due to being away from the car for so long now. My basic question is, what are some of the major things I should look into if Im loosing charge on my battery from it sitting for a few days or a week at a time between me touching it? Thanks in advance.

[DaveN]

1st checks:

1. (a long shot, but easy) If the top of the battery is dirty clean it. Underhood dirt can be conductive enough to slowly drain a battery.

2. Disconnect one battery cable (with the battery charged) and use a DC ammeter to measure current between cable and the battery terminal with everything in the car turned off. Should be ca. 100 milliamps or less. If the leakage current is OK everything other than the battery is OK, so it must have an internal (high resistance) short. That's not unusual in old batteries or after a few deep discharge cycles. If the leakage current is high you'll have to trace it through the wiring or just disconnect things 'til it goes away.

[Montezuma]

I had the same problem with my 78Z, it turned out to be a faulty pigtail on the ignition switch. I got a new key set installed and the problem was gone. What was happening was the old pigtail was keeping the car "on" thus drawing current. It would not cause any problems as long as the car was run every day or so....but let it sit for a week forget about it, the battery was dead.

[MikeW]

Another possibility is a drain somewhere unexpected. With nothing turned on there should be almost no drain on the battery (the clock and or aftermarket radio will always have power). You can remove one battery cable and hook an ammeter in series. That will tell you what your actual constant drain is. You can then put the battery cable back on, get in the car, and go through one fuse at a time. Simply remove the fuse and jump the gap with the ammeter. When I had this problem I used this method to narrow it down to the dome light. There must have been a high resistance short that didn't blow the fuse but drained my battery overnight as if the dome light was actually illuminated.