To start off, I had this same problem last winter, and ended up having a shop rebuild my entire wire harness. The problem stopped, but it's back again this winter :-(


My electric meter in the car used to read 13 while I drive the car, and then would read about 8-9 or so when I start it up again the next morning.

NOW while I drive, the amps don't even get up to about 12, and when I come back and start the car only an hour later, there is bearly enough to start the car up again :-(

I have check the alternator various times (both in and out of the car) and it always checks out good, the battery has been replaced a few months ago, and just recharged this afternoon. The belt on my alternator is nice and snug, and I am at a loss as to what to do again. no way in hell I'm going to have the harness rebuilt again.

Something has to be draining the power when the car is off (and while it's on), but I don't know where to look. I disconnected my alarm, and that doesn't make any difference.

Any ideas? much appreciated!

 

Make sure the battery cables are tight. The alternator should push the volts up past 13.5 when the engine is running. Do this troubleshooting with a fully charged battery(charged with a battery charger not just the alternator). Lots of things can pull excessive amps from the battery--basicly anything electronic has the potential to cause a draw. The alternator and radio are a couple that come to mind as far as recent ones I've fixed.

 

Hook a mutilmeter up between the battery cable and the battery terminal and read the amperage draw while the car is off. Then start pulling fuses until the draw goes away. When the draw goes away you've found the culprit circuit. Then just troubleshoot the circuit until you find the cause.

BTW, there will always be a small amperage draw from the radio's memory circuit, the factory clock (if equipped), and maybe one or two other accessories. This draw will be minimal though. My guess is that you have a significant draw from some faulty circuit.

 

Several things come to mind here:
1. What kind of audio system do you have? If it is a higher end one, you probably have a security light or something of that nature, and there is a way to turn it off.
2. Is the battery fine after a long while if you disconnect it from the back of the alternator? If it is, the alternator needs to have its diode replaced, if that is even possible (depends on the model you have).
3. If you have vent caps on the battery, remove them and check the water level in the battery. If it is more than 1/4 inch away from the bottom of the holes, you need to add distilled water (boiled if you can't find any locally) until you reach that mark.
4. Along those lines, check the battery's cells with a hydrometer. that will most certainly tell you is the battery is good or not. Those battery tests that are done in 30 sec at parts stores are unreliable and useless as far as I am concerned.

If none of this helps, you might need a NEW wiring harness. The shop may have screwed up along the line and messed with some insulation. When the insulation is warm, it may just barely be covering bare wiring, and when it's cold, it contracs and leaves the wires bare.

Just a couple of guesses. I hope my drain is fixed...