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sneed21 · Guest

'80 924

I've got a battery problem. I just got a new battery....placed in Car...Car ran fine, no battery light came on, so I'm assuming the alternator was working fine...never gave me any indication that it wasn't, AC worked, lights etc.. (drove it for about a month)
I went on vacation, and came back two weeks later. When I went to start the car, it wouldn't even turn..just clicked. I jumpered the car and it started right up. Disconnected the cables, turned the car off (after it ran for a while) and the car would not restart, just cliked again. No problem, I took the battery out and hooked it up to the charger...But it Will not hold a charge. I've never heard of this....If the alternator was bad, would it "kill" the battery? The car couldn't have run fine, w/ the AC running (I'm in Florida)if the alternator was bad....would it??? What would cause this, and/or any ideas on how to fix it? Oh, and the previous owner said the car did it to him too.

Thanks!

Diesel · Guest

Short answer: Yes, the alternator can let power go OUT when the engines not running if it is bad. It will give notice usually, the lights will get brighter when you rev the engine, the voltage will be a little lower than normal....You have a draw somewhere basically. It could be something as silly as the glovebox or under-hood light stuck on, or a dirty battery(really!). You need a good DVOM and a manual if it gets tricky.

sneed21 · Guest

Thank you!, but what I don't understand, is that, if I have a draw on the battery, from whatever, (and it completely drained the battery)it shouldn't short the cells, and keep me from being able to recharge the battery....the lights don't dim and brighten as I rev the engine, and I have ample spark, etc..(which doesn't make sense after jumping it, letting it run and driving it around with no symptoms of a bad alternator, then turning it off after a 30 minute run and not haveing anyting when I try to start it again) unfortunately I think this is more tricky than a sticking light or a bad alternator...

thanks for the advice!

a.

Diesel · Guest

1st: Don't let having spark fool you, running the ignition system takes about 3 or 4 amps. You can have a transistor radio battery supplying the spark. 2nd: rule of thumb is if you've 'killed' your battery, that is let it be drawn down to nothing by a draw in the system, 3 times.........it's junk. True, it MIGHT bounce back that 4th time but in reality, 3 times and you are SULFATED. You need to find which circuit is taking the load from your battery when it sits still. One way is to disconnect the positive post and put a 12V test light between the battery post and the batt. cable. If you have a draw it will light the test light because voltage is passing through it. Pull fuses, check components for being active and disconnect starter and alternator(in that order) until the light goes out and you've found your draw. Don't forget to push in that door switch while you do this test or you'll never get the light to go out!

sneed21 · Guest

Thanks again for your advice......

bacook · Guest

Good tip! I never thought about using a light in-line of the positive post and cable to test for a short. I'll have to remenber that one.

Diesel · Guest

numbers · Guest

Generally, if your battery is going down while the car is sitting, you have a current draw somewhere in the system. One common place for this current draw is the rectifier in the alternator. If one or more of the diodes is/are shorted, it will run the battery down fairly quickly (like overnight).

You indicate that your battery will not take a charge. What do you mean by not taking a charge. If you have a trully shorted battery, when you hook up the charger, the current meter will peg on high charge, and then the circuit breaker will pop. if the battery is sulfated, it will take a high charge initially, but taper off quickly, and indicate full charge after only a few minutes. If the battery takes a high charge initially, but continues to draw an amp or two overnight, it is good, but was run down. Give me more detail on your symptoms and I will try to help more.

mdaniel83 · Guest

if one or more diodes are shorted, then what's the best solution? change the alternator?

Roger Hall · Guest

i had an old sunbird that had the same problem the current draw was much less the battery would last a couple of days without a charge but i didnt kill batteries that fast have you checked for a draw on the battery maybe its not the car maybe the battery had a bad cell when you bought it

D Hook · Guest

Had the same thing happen to me. I had bought a new Sears DieHard and put it in and a couple weeks later, battery kept going flat. Replaced the alternator, went through all the wiring, did the in-line light test, etc. Came to find out the battery was bad from the start. Put an Interstate in and haven't had any trouble since. (knock, knock)Might be worth it to pull the battery and get it tested to be sure. I had one like that in my wife's tahoe, too. But that was some other brand.
Also, be sure your battery is fastened down under the hood. If not, all the jostling around when driving can cause a short in the plates, is what I've been told by mechanics. Makes sense to me.
Good Luck!

sneed21 · Guest

Thank You all! Looks like I'm gonna be busy trying all these tests and remedies;)

Thanks again!

a.

numbers · Guest

The rectifer can be replaced in Delco alternators, but I am not sure about the Bosch. Anyway, it is a PITA job. I would take the alternator to an autoparts store and have it tested. If you have a shorted diode, the test will indicate low output under load. Then replace the alternator.

Diesel · Guest

I have an alternator if you need one. Just drop me an e-mail.

Joes924 · Guest

To get started .. alot of places, tire stores,auto parts places check the charging system for you ...A alternater/ battery store here sells both for our cars 9 rebuit of course but for 65.00 'alt' its not bad
compared new from 1 of the mags that puts out perf.parts.