power drain

[rif222]

I have a 72 240z. After the car sits overnight, the starter turns over slowly. The starter is new and so is the battery. When I charge up the battery overnight, the starter turns over quickly. I have heard these cars have some electrical issues. Any insight on what else could be draining my battery? Thanks.

[zbane]

Assuming that there are no obvious causes, like leaving the parking lights on inadvertantly or leaving the car in the ACC position, I would think that you have purchased a "bad" battery. It's happened to me before.

[beandip]

It could be any of a number of things . If the battery is going flat overnight . You have a serious draw. If you have a multi meter . connect it in line with the ground battery cable so that you can measure the amps being drawn from the battery. (disconnect the ground cable and check for current flow between the neg post and the cable connector) . You should see a reading showing power be drawn form the battery. Now go to the fuse panel and one by one remove the fuses watching the multi meter . When the meter shows the draw is gone , you have found where to look for the trouble. ( if you don't have a multi-meter , use a 12v light bulb connected to a wire so you can put clip the wire end to the battery cable and touch the bulb to the neg post. If the light lights , this is power flow drawing off the battery. When the light goes out when the fuse is pulled . that is the offending circuit. I hope this makes sense . Gary

[DeesZ]

I had a similar problem on another type of vehicle ('52 M38A1 military jeep). After trouble shooting the circutry for about a year and still not finding the problem, an old-timer suggested that I check out the starter switch. That was an old floor pedal switch, but the 'theory' for the switch is similar for almost anything. I pulled the switch and checked it out with a multimeter for continuity. That was where the problem was, a very slight drain on the battery was caused by a carbon and dirt build-up on the contacts. It didn't read much on the meter, but over a two day period it was enough to drain the battery enough to prevent me from getting it to start. All I had to do was clean up the switch contact points and the problem was resolved. I am by far no electrical whizz, but I'd give that a check as well as the headlight switch (or anything else that is switched directly from the battery on a different curicut). The most obvious and probably the most common has already been suggested... a bad battery. I replaced them (two 12 volt in series) on the jeep too before checking the switch - that turned out to be an expensive process of elimination. Please let us know what the problem turns out to be when you find it.

[Arne]

Another thought for a 240Z is a defective alternator diode. If it fails, there is a pretty serious draw on the battery. That can be checked out by most anyplace that repairs electrical systems, as well as many parts places.

[SteveJ]

Another thought for a 240Z is a defective alternator diode. If it fails, there is a pretty serious draw on the battery. That can be checked out by most anyplace that repairs electrical systems, as well as many parts places.

Don't forget that a bad regulator can cause such a draw. I had that about 11 years ago.