Cwaters

My battery is dead all the time. The alternater seems to be working ok while the car is runnint (14ish Voltz). So I think it's someting draining the battery while the car is parked. To add to the problem, it seems to be intermittant
So what's a good course of action in finding a battery drain?

Cory Waters

13BAce

It could be that your battery terminals are bad.

Cwaters

How would this cause the battery to drain? I mean, it'll be DEAD DEAD DEAD.

Cory

RX-7 GT

check your alternator belt.

also terminals can be the cause. it was for mine. mine were all ratty. i bought a new battery, put it in and turned the key it started. drove around shut off car. started back up completely dead. wiggled around cables back to life! get some new ones there cheap.

Keith

Just a suggestion. I have had 2 alternators in my 30 years of working on cars that have developed intermittently shorting diodes. As long as the diode doesn't short (break down), everything is ok. When it does, though, you have a very high amperage direct short to ground, and I have seen a brand new battery not even be able to light a flashlight after a few hours. Always seems to happen while the engine is shut off, maybe because of high heat??? Only way to troubleshoot it is replace the alternator. Sorry.

Irv, Keith's dad

Samps

disconnect the battery and let it sit for a few hours. If it drains without even being hooked up to anything then your battery is no good. After a battery is drained a few times the plates inside of them start to warp; and when they finaly touch each other then your battery will actualy short itself out. This happened to me, and only after I removed the entire wiring harness did I check the battery. Believe me, check the battery before anything. And don't just take it somewhere and have them hook it up to a machine, because that will not tell you if the battery is shorted. All you need to do is take off the cables and check the voltage, then come back 2 hours later and check the voltage again. If the voltage dropped then you need a new battery, if not, good luck man...

The Ace

You know, there is this thingamyjig called "Battery Tester", and its called like that for a reason: you can test batteries !!!!! Unbelievable, aint it ?

So take one of those, and simply connect it to your battery. It'll show you the current voltage, the current capacity, and the battery's ability to recharge and hold on to that charge (by a series of leds). Its like a 2-minute procedure. If your battery is dead, it'll show.

HAILERS

I'd take Keith's suggestion to heart. What you could do to prove that the problem is the diode in the altenator is.....at the end of your day make sure the batt is charged up. Now disconnect the wire from the altenator. Wake up in the morning and check the battery. If its in good shape then the problem seems to lie in the altenator. The post about checking whether the batt is any good in the first place makes good sense. Some auto stores like Pep Boys will check it for free. I think you just hand carry it in to the counter and the fellow checks it. Never done that myself, just noticed one on their customers doing that.

Cwaters

Battery checks out OK.....

COry

The Ace

So, if the battery check out OK, meaning that it can fully recharge AND hold on to the charge (doesnt leak), and this happens only when the car is sitting on its butt, then something else is leaking or short-circuiting. Irv has it down: disconnect (+) for the night, and check car the next morning. If it starts up fine, then you need your WHOLE electrical system checked (, not even want to think what this means). If not, then you didnt check the battery properly, or you live in ONE HELL of a moist enviroment ...


PS: Are you sure you are not forgeting anything on during the night, which drains the battery ? Just a thought....

go_speed_go

Have you pulled off clamps on the terminals?

I had similar charging problems. Both times I thought the battery was shot. Both times I had a LOT of corrosion on the inside of the positive terminal clamp. Without a good connection there, you can't get power in or out of the battery.

Cwaters

nothing I can think of, switch off, lights off.....

CW

Cwaters

the battery was purchased in April because I was having the same problem. I took it out yesterday and had it checked. It seemed to keep a charge yesterday afternoon while it was on the floor in the garage. Took it to a shop and when load tested, it was like .4 amps....they charged it up and then it tested out ok.
SO
while running, I'm getting like 14 amps. Seems ok but I guess I'll take the alternator in for a test next.

Thing is, some days it works fine and other days, it's dead. If I get it running, it'll run to wherever I am going, but there's no telling if it'll start again.

Cory
not looking forward to the pull a fuse, check the meter dance.

Ryde _Or_Die

My old car would die every-once-in-a-while. It got worse n worse. I figured the alternator was shot. Took it out & had it checked & it was fine. I replaced the battery & it was fine. Thats my 2. Shorted out battery. You have an amp going to it?

Icemark

What is the current draw on the car when the key is off... if your battery is coming up dead all the time and your voltage gauge is working, chances are you have a current draw problem with the car.

Current draws can come from simple things like a light on all the time or an aftermarket stereo or power ant wired wrong.

Get your multi-meter out and test the current draw of the car. It should not be over 60Ma with the key and lights off. Anything over 80Ma will drain your batter in about 4 days, and anything over 100Ma could drain the battery over 24 hours.

Alternator, smallternator... betcha you just have a draw in the car.

And if you don't have a multi-meter (which you should if you do any car work yourself, they are only like $25 at radio shack for a cheap one and $100 for a really good one) don't take the car to some mechanic using a test light, make sure he tests the current drain with a meter.

13BAce

It wouldn't drain the battery, but your accesssories wouldn't get any power.

13BAce

If you want to test the terminals first test the voltage at the battery posts with the car off: Should be 12 volts. Then test the voltage at the terminals: Should also be 12 volts. If it's very low then the problem is your terminals.

RX-7 GT

for future reference your not supposed to leave batteries on pavement. it drains the life out of em. put it on some carpet or a mat next time

Icemark

Thats an old wives tale from the days before nylon battery cases.

Boosting_FC

My suggestions:

1. check to see if there are any acc. that's on. Look to see if there are lights (maybe in the trunk, alarm, etc... you get the idea). I'm sure you did this already. A firend of my (w/ a Corvette, but that's irrelevent) had his battery drained always. It turned out the passenger vanity mirror was not fully closed so the light was always on, lucky we don't have such nice amenities. Just an example. So check to see if everything is OFF.

2. Check the battery to see if it is still good. You probably did this already too.

3. Now, check the ALT. You can do this by starting your car (no accessories please) and pull the connector off the battery. If it's still good and charging, then your car should still run. This is the easiest way to check for the ALT w/o expensive tools.

Hope this helps...

Jay

Six Rotors

iTrader: (17)

Icemark has the correct answer.Perform the test and go from there.

Cwaters

Here is a battery FAQ that I found online:

http://www.uuhome.de/william.darden/carfaq.htm#4

Hope this helps somone.

Cory

Ryde _Or_Die

Just take the alternator off and take it to have it tested at discount auto parts or somewhere if you haven't already. I did this and it took about 10 mins to take off.