battery drain

[metalkiwis]

i got an 85 with the 305 engine and i am having to charge my battery every other day. the alternator is testing fine off the car. the battery is brand new. two days old. have been having this problem and figured i just needed a new battery. the wire clip from the alternator is in good condition. what would cause the battery not to charge? what am i missing?

[kdrolt]

http://impalassforum.com/noncgi/ulti...ubb=forum;f=25

then search for the word drain

Lots of threads there that cover all of it. A faulty radio is one common source of the drain on the battery; a dead/hidden theft alarm is another.

http://impalassforum.com/cgi-bin/ult...;f=25;t=003728

[silicon212]

I even had an electric seat cause a drain at one point - in that case, it was the main power wire going into the motor in the seat which had an intermittent short - not enough to blow a fuse or start a fire, but definitely enough to cause the battery to drain overnight.

The point is that it can be anything electric causing it - kdrolt points out two very common causes, so I'd search those out first.

[metalkiwis]

it drains when i drive it not when it sits. i will check out the radio and alarm. thanks guys.

[capriceowns]

If it drains while you drive. your alternator could have bit the big one.

[metalkiwis]

no, i got a new alternator. i got it at autozone. had them test it on the car and they said it was bad, but took it off and they tested it on the machine and they said it was perfectly fine.

[capriceowns]

Well thats weird.

Heres what I would do.

Step 1. get a volt meter, and set it to 20 volts
Step 2. Go over to your battery while the car is off and nothing on, and see how many volts it has. should be 12-14 volts. (after you charged it)
Step 3. now start the car and see how many volts the battery is getting, it should be roughly around 13-14. if the voltage drops any the battery isnt getting charged. you can turn you lights on, heat etc to see if it wil drop faster.

If it drops and keeps dropping then something is up with alternator.

[dan21399]

The exact same thing is happening to me. I thought it was my battery, then alternator so I changed both and still was having the same problem wit the car not starting. Today I had it looked at by 3 different professionals - the battery and alternator both tested fine. And everything else looked good too. They all came to the conclusion that the car wasn't being driven enough. I am glad that this is the case but it doenst make sense to me. I've have the same commute to and from work (25 miles round trip) for 5 years and it never seemed to be a problem.

[HLandin]

I would agree with the idea that, in both of these posts, some load is draining the battery while the car is not running. The battery may be fine, but if you have a load (even a small load) that runs while the car is not, it will eventually run down your battery. Check to see whats running with an amp meter or something similar, and find out what the load is.

[bobss396]

I agree that some pissy little thing like 2-3 amps is the culprit. Look for stuff like a glove box, underhood or trunk light that stays on. Normally you should be able to let the car to sit for at least a month and have it start right up with a decent battery in it.

Bob

[alan &marge pepper]

your alt. is fine and your batt. is fine. my question would be is the curent getting from the alt. to the batt.
alan

[rhandwor]

After your battery is charged and you have a good alternator. Disconnect the battery ground get a 12 volt test light. Connect the light to the ground strap touch the negative terminal. If the light shines bright you have a drain on the system. At this point pull one fuse at a time until the light goes out. If it still stays light with all fuses pulled disconnect the alternator.
Hood lights,trunk lights,external voltage regulators,dome lights are all problem areas. Newer vehicles stuck relays are a problem.

[silicon212]

Don't use a test light. Use a multimeter instead.

Set it to Amps, using the 10 amp scale, and wire it in the way that rhandwor above states with the light. You want the battery power to flow through it and measure amps.

You should have a power-off flow of about 300 milliamps (~0.30) on the system as this is what the ECM is pulling. This is normal, and it is enough to light some test lights up brightly, which is why you don't want to use a test light. If it's in the amp range, then follow the above advice for tracking it down regarding pulling fuses one at a time.

[dan21399]

Just had my car diagnosed...BMW dealer said it was the blower transistor causing the drain on my battery.