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Very annoying battery drain issues...

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Cream79L82

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My car runs fabulous when started. The trouble is I can't get the thing to start. I was jumping it for about two weeks trying to figure out if I had some major battery drain that was killing it because the half wit at O'Reilly's said the battery was fine when I had them check it. I didn't even know how old it was (at least a few years) and not even a closed cell so I finally decided that I should just replace and see if it simply wasn't holding a charge. That seemed to fix the problem because she started up like a champion... and continued to for about a week. I even had let it sit for about 3 days and then it still had plenty of charge to start right up.
It wasn't until I didn't drive the vette for 6 or 7 days. When I went to start it was pretty well dead. The very annoying thing was... it didn't seem alternator was doing anything to re-charge it once I started it. What is so confusing to me is the engine purrs just great all through the power range.. I have an amplifier and an aftermarket system and it all runs great, my headlights and accesories have adequate power, and my volt gauge reads steady to the right side of 13 volts. The quartz clock, though noisy, keeps perfect time. It doesn't seem like it should be able to drain the battery between sittings. A friend suggested me that it might be that the problemis the generator provides enough current to run everything just fine, but not charge the battery. I jumped her last night and drove it probably 10 minutes to the OU vs. Texas tech basketball game. It sat for about 4 hours, and it wouldn't start yet again.

I hope some of you have diagnosed similar problems before. What sort of checklist should I go through? Would taking the alternator to a parts store and having them check tell me definitively if that was the problem?
Thanks in advance.
 
My thought would be driving your car for 10 minutes would charge the battery enough to allow a restart :eek

Would taking the alternator to a parts store and having them check tell me definitively if that was the problem?
YES, this is if they have a setup to test it. Most NAPA stores do and most Kragens.

Another very quick check is the alternator connections, be sure they are clean and a good solid connection. I would check the connections and take the alternator into be checked. These are 2 real simple things and will eliminate them if check out ok..

Next would be to find the circuit that is causing the current drain.. There are many things it can be, to be honest with you, take it step by step. We have a lot of talent here and most of us have gone through this agravation too at one time or another. If you have a GM shop manual, refer to it and keep a record of all things you check. The list will keep you heading in the right direction and provide a road map of where you've been so you don't start back tracking and wasting time retesting circuits and components.[/
 
If you have a volt meter, check to see what kind of voltage the battery has with the car off. Then start the car and read the voltage. With the car running it should be somewhere about 14~14.7 volts. If not, I would check the voltage at the terminals on the alternator. Expect to see the same voltage as above. If you have the 14~14.7 volts at the alternator and not at the battery, you may need to start looking at grounds.
Hopefully someone will chime in with a few more hints.
 
The K*I*S*S system is usually best. (Keep It Simple, Stupid). With a volt meter check the battery at the terminals static (engine off) any 1.5 vdc reading less than 12 vdc indicates a dead cell. Also commonly overlooked is to check for a good 12 vdc at the chassis ground for the battery. Clean under the lug if needed. Let us know how it goes.

Greg

Greg
 
Alright fellas, thanks for the input. It seems apparent that I need to get to the parts store tomorrow. I'll probably have the saps check the alternator while shopping for a voltmeter....

I'll let you know how that turns out.
 
if your alternator isnt putting out enough juice and you bump up the volts make sure you get the correct voltage regulator. I forgot to do this and overcharged the battery on my 66.
 
Hey Cream, how did you enjoy the basketball game, I was there also are you going to the Big Monday game with OSU? Where do you park I would like to see your car?

As far as the battery drain, on my 76 the battery would go dead if the car sat for more than 2 days but after I got it started everything was fine. The problem was the alarm system master relay was stuck closed and draining the battery all the time. I unpluged the relay and that fixed the problem. I am not sure if you car has the same alarm system as the 76 or not but its some thing to check out.
 
Okie.. I don't currently have a ticket for the OSU outing but would love to go. Where is the master alarm relay? I have an aftermarket alarm system that needs to be re-programmed after the battery in my remote died. I haven't really checked any circuits yet... but that alarm always was a little wonky. If anything wasn't grounded fully could I get battery drain. Such as that alarm or my deck? I just put the new deck in around Christmas and I think it might have something to do with my problems. In fact, the accesory on/off switch isn't working right. That is the deck doesn't turn on and off automatically with my key being turned. Could this because of a bad ground? I checked and double checked the two hot wires to make sure which one was activated with the key in the acc. position. Just some more thoughts.
 
Sounds to me like the deck is causing a drain on the system, if this is the case you should be able to see it with a volt meter. You can always unhook the deck and see if the problem goes away if it does then you know what it was. I have a voltmeter so don't buy one if you want to use mine we can work it out. Go SOONERS
 
Just got back from the auto store. The ole Delco-Remy unit kicked right up to 14 volts and held steady. I biked the two miles over there right after I jumped the vette, drove her for about 10 minutes... it ran real well, and then as soon as I shut it off and tried to re-start it, I didn't have enough power to start. Even if I've got some major draining or bad grounds, that doesn't make sense that I couldn't even bump a hot motor, with a hot battery, and start it with ease.

I think it might be I just got a brand new P.O.S. battery from O'Reillys. I didn't really want anything special so I just got a very average battery, but there's no reason it shouldn't work after 15 starts in 2 weeks.

There's something else I've been wondering that you all probably know. I've owned the car for close to two and for all that time one of wires that plugs into the top of the alternator has been broken. I noticed a long, long time ago, but at that time I never had any electrical/starting/charging problems so I assumed it was unnecessary. I hooked it back up this summer, but then in an attempt to diagnose my non-starting (turned out the NEW coil was burned up) car on the side of a turnpike in August, I decided to cut it because it had worked fine without it wired. I'm 98% sure it's unrelated because everything has always fine without it, but I would like to know what those two top wires feed.
I guess my next thing to check is the battery? This sucks.
 
I am not exactly sure what the two wires are for but I do have wiring diagrams at home. I have several maintenace manuals for the C3. I will look when I get home and if I see any thing I will send a message. It does not sound like you have a drain on the system something else is wrong. I will look at wiring diagrams and let you know what the wires on the alt are for. PC
 
One of those two top wires (can't remember which one) is the voltage sensing lead that senses battery voltage and tells the internal regulator to start the alternator charging; if it's not connected, the alternator won't charge, regardless of the state of charge of the battery. I think you found your problem. The alternator will check out fine on the tester at the parts store, but won't charge the battery when it's installed in the car (with no sensing circuit).

:beer
 
You're probably right JohnZ. I just never thought of it because I literally drove the car for months and months, through 100-10 degree weather, and it never had charging problems with that wire not hooked up. That was with my previous battery though. Do you think the situation is changed with this new battery? Or do you think that hooking that other wire up might have had anything to do with the coil burning up? I got to go camping tonight and clear my head....
 
Well I guess it's a testament to the durability of GM and Delco parts that the part that crapped out on me was not a 25 year old alternator, wiring or battery cables... indeed it was the 2 week old battery. Piece of crap. I found a larger battery with more cranking amps for the same price at the store though. So.. knock on wood... problem's solved. :upthumbs

We'll find out if that top unhooked alternator wire is related to that charging problem. I really think it just crapped out. Hope that's the end of this thread...
 
Just a thought:

If your ignition switch isn't turning off your accesories, it could also not be switching off your voltage regulator when you remove the key. This would cause a drain on the battery through the charging circuit over time.
 
Hmmmm.. interesting point. It seems like the switch itself is functioning properly, because when I put it in the acc. position, the (stupid) fan comes on low and all the correct lights come on in the interior, and they switch with the key. It is only the deck staying on as best as I can tell. When the weather gets nice again I plan to recheck that wiring. Can you think of any other way to test if that voltage regulator is indeed still on? Would a test light show anything anywhere on the alternator with the key out?
 
Unless you have a deep cycle battery, after it is drained a few times the battery is ruined. Probably not so much a cheap battery as the fact that it was killed off by being your non-functioning charging system.
 

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