Dead Battery Overnight

[barrelguy]

Went out for a spin last night and everything was fine - started right up, ran great. Parked it in the garage and went to go out this evening and ... nothing, nada, zip. Ignition lights came on briefly and got a brief click from somewhere under the seat then nothing. Hooked up jumper cables to the car and it started fine.

I'll put it on the trickle charger over night and see what happens tomorrow but the question remains what caused the battery to die in th first place. Any ideas? 1980 1100SG. Thanks

[CatatonicBug]

When you parked it, did you use the fork lock? If you turn the key ALL the way to the left, PAST the lock position, it will leave the tail light on, and drain the battery.

Otherwise, how old is the battery? They usually last about 3 years or so, so it may be getting to the end of its usefulness.

[natemoen]

Have you checked the electrolight level in the battery recently? If not check it and fill as necessary with distilled water only.

[jetmechmarty]

Do you have a test light? Go buy one at your local auto parts store. They're inexpensive.

Take the positive cable loose from the battery. Clip the cable end of the test light to the battery and the pointy end on the positive cable terminal. The test light should be connected in series. Does the light illuminate? (if it takes all night to kill your battery, the light will be very dim) If yes, you have a ground someplace that shouldn't be. Pull the fuses one at a time until the light goes out. That will tell you what circuit to find the problem. Disconnect plugs in that circuit systematically until you get to the problem.

If the light didn't come on in the first step, follow the other suggestions.