Thread: Battery trouble

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I have just recently run into a battery drainage problem. I bought a new battery and alternator. It still is happening, my car has also started detonating. It is really getting on my nerves! I cannot for the life of me figure out what it is. Any ideas guys?

Without knowing what car you have, it's hard to tell. Get a multimeter, that's the kind that reads volt, ohms, and amps. It's the amp draw that you want to read.
Pull your positive cable off. Clip the red lead of the meter to the battery post, clip the black lead to the positive cable. It will show some reading, this is normal. A few milliamps is ok, if you have a computer in your car. If you have a burglar alarm system it may read 250 ma (1/4 amp). This is high, but acceptable. If you read more than 750 ma (3/4 amp) something is pulling amps. While the meter is still connected, pull one fuse at a time and look at the meter. If the reading drops drastically, then that's the source of drain. Start looking in that area for a short or incorrectly installed item.
I have found this problem in more cars that have just had a new radio installed. The installer had grounded one side of the speakers. In some of these new radios, you have to keep the speaker wires separate from ground. The power amps have to be wired correctly also.
You'd be amazed at how many guys install big radios with heavy power amps using micro thin speaker wire and run them under the door sill to big bass speakers. After a few good boom boom booms the insulation melts and the wire touches ground. First they get a bigger battery, then a bigger altenator, and finally they're at the radio store screaming at the clerk that he sold them a crappy radio.
Here's things to look for:
>New installation of electrical items. Look to see if the power wire goes to the fuse box and not some easily accessible hanging wire.
>Three wire (GM) altenators using only one wire.
They have three wires for a reason. One of them is a voltage sensing wire to tell the altenator when to charge.
>Loss of power or weak accelleration (computer related).
Computer microchips are sensitive to heat. Why they mount them close to the heater is beyond me.

Good luck in the search.

I do have a 100 one wire alternator....but it has never been a problem before. I drive a 75 chevy nova with a 350 crate.

Do the multi-meter tests first. You may have something draining your battery.

If your altenator is made as a one wire unit, it may be the problem. If it's a 3 wire unit and you're only running one wire, that's the problem.

The large red wire from the altenator is the battery charging wire.
One of the terminals goes to the gauge.
The other terminal is the sensor wire. It runs to the fuse block and reads the voltage at the fuse block where all the electrical items feed from. If this voltage reads less than 12.6 then it will trigger the altenator to charge the battery to the proper voltage, so that all the electrical items can get a 12.6 voltage to work properly. Some one wire altenators have an internal wire from this terminal to the large red wire terminal. As the battery drains, it constantly reads anywhere from 12.6 to 18 volts, and won't trigger until the altenator reaches high speed.

Scenario:
3 wire altenator,
Proper voltage and charging rate at the battery. Proper voltage at all times at the fuse block. Lights nice and bright, 12.6 volts at the HEI distributor giving a good 20,000 volts to the spark plugs and a good clean burn.

1 wire altenator,
Improper voltage and charging rate at the battery. Low voltage at the fuse block. Lights dim, radio low, horn sounds like it's dying. Only 9.6 volts at the HEI distributor giving a mediocre 15,000 volts to the spark plugs, resulting in an unclean burn, leaving behind deposits to cause detonation or pre-ignition, poor excelleration, and poor MPG's

Like I said, do the multi-meter tests first, then if you still have the original wiring, swap out the one wire altenator for a 3 wire altenator and see if that doesn't clear up the problems.