I have a 76 l82 4 speed, I cannot get the battery to hold a charge. I have replaced the altenator and the battery. I have no clue as to why it will not stay charged. Loses charge overnight. please help before I take a lighter to it.

 

You have a power device active with the key off....first step, get a volt meter and put between positive bat post and pos cable, with key off, doors closed and see what voltage reading you get...should be minimal, if not, start pulling fuses until the high reading goes down, find what devices are on that fuse and correct the "on" condition of the culprit....this is a good start, report what you find or don't find here on the forum...and please, don't set the vette on fire

 

Actually what you want is a volt meter set to Amps and your going to measure the current in the condition above. Some possible culprits: Power antenna, Interior light timer(orange gizmo behind pass side dash) aftermarket alarm

 

That's right, that's right, I knew that :o
Late NASCAR nite....not enuf coffee yet...thanks for the correction

 

Do you have a Carb with an electric choke?? I had the same type of problem once with my 78 and it was my electric choke draining the battery. Thought I had a switched connection, but I didn't.

I wish you the best of luck if this isn't your issue.

Jeff

 

Electric choke??? heck if I know. Was that standard on a 76 or an option?? I've only had the car a few months. Going to try the suggestions as soon as I get the right meter. Thanks for the help. Willlet ya know my progress or lack of it.

 

You souldn't see anything higher than .01 amps if nothing is drawing from the battery. Over that and you have a draw. A computerized car can see a dead draw of up to .1 amp and do fine as a regular driver, but a garage queen will need a top up of the battery every couple of weeks or so under that draw. If you see a 1 amp or so draw on your system, this usually means a relay is closed. Check the power windows as the usual suspect. A 1 amp draw will kill a battery overnight. A good DVOM is critical to good diagnostics.

 

I drive the car everyday, went dead overnite.new battery too. also where is the fuse box located? I cannot find it.

 

Use one of these until you get the problem solved

 

o.k. I put a test light to the +battery post and the cable. It lit up. should it or do I need to go buy a meter to test it right?
Noonie, thanks for the idea I will put one on tomorrow.

 

A test light is only useful to see if a circuit has power(completes a circuit), which is not useful info for you. You know it has power because power is what's killing the battery. You need a digital volt-ohm meter.

 

Cool, Thank you.

 

yeah man i had the same problem. i couldnt figure it out so i bought a battery disconnect. it turns out the silenoid that bumps the idle up when the ac is on was always on. being that my a/c doesnt work we just disconnected it. you could also wire it into the wires that run from the compressor so it only comes on when the a/c is on(if thats your problem) good luck finding your problem but its probably not going to be easy

 

you need a voltmeter with amp measurement capability. Electric choke is the round gizmo on the pass side of the carb with a wire going to it, if you have one. Disconnect the bat + cable and connect the amp meter between the bat + term and the cable that came off it, see what you get. Should be in the zip code of 100ma or less. If higher then you have something on somewhere. This test should be done with the key off, doors shut. There is a ctsy light timer (small orange box) behind the pass side dash that dies sometimes. Take the measurement and let us know what you get.

 

If you choose the "pull fuses until the draw goes away" then a test light would work fine. The issue would come if you had multiple draws that, when one is corrected the other doesn't have enough current to activate the bulb. All looks well but the bat still dies...

 

The first thing you need to do right now is disconnect that battery. Go out and buy two things...a battery disconnect like noonie suggested, and a meter which reads DC amps...you don't need any AC stuff for a car...make sure it will read up to 2 amps...most good ones will read up to 10 amps...the higher it is capable of the better prepared you will be. While you are there see if they have the Haynes Repair Manual for 68 through 82 Corvettes...it has full circuit diagrams...you will need that to figure out what devices might be causing the drain.

After you get the battery disconnect in place here's the process:

1. Pull all of the fuses and check that they are all the correct amperage as indicated on the fuse box...fuse box is located under the driver's dash near the high beam switch...a plastic fuse tool is also nice to have, but I use a small screwdriver to pry at the ends of fuses...NEVER try to pry on the glass with a screwdriver or other metal or it will break...even that plastic tool has cracked the glass on a fuse or two...and pry carefully.
2. Connect the ampmeter at the battery between the cable and post...use the + terminal for convenience since it will have the disconnect in place which will be easy to attach...DON'T TURN ON THE DISCONNECT.

If you get a current reading with all the fuses out then you should start by looking at the starter connections.

If you don't get a current reading then replace a fuse and check the meter...if no current is flowing then remove it and try the next fuse. Keep doing this until you see a current flowing. The clock will draw almost 100 milliamps (.1 amp) which is fine. If all you see is .1 amp or around there then make a note of it (write it down on a piece of paper) then pull that fuse and move on to the next. What you are looking for will probably draw at least 500 milliamps (.5 amps).

Also, be very carefull around the battery, open wires, and fuses...things can get hot and burn you if the wrong wires touch each other. When working with wiring I always have wire cutters, electrical tape, and extra 12 gauge wire nearby for any quick repairs.

Keep us posted.

 

I'll be off to the parts store as soon as they open. got my list of things to buy, list of things to try. (my lighter is still handy). I'll keep every one updated. A big ole THANKS to everyone for helping me.

 

I just rembered that when I got it from my dad he had told me that once in a while it would have no battery power when he turned the key but a couple of turns later it would be fine. Still going to try all of the suggestions, but would this change any ones idea of what it could be.

 

I know you're off to the parts store but I should have mentioned this yesterday....in the dark, and I mean nite black dark, take a walk around the car, look under and stuff...there might be a light on you can't see in the day.....happened to me....door courtesy light button on the driver door wasn't going all the way in, inside lights on 2 days....battery was dead (mortal), but being a new battery, a jump and a (very long) ride and it was better, then a nipple on the button, all better...
Just an afterthought....Good Luck

 

Ok here is where I stand, parts store didn't have a tester in so I will have to wait. I did put in the disconect on the battery.
what will happen if I take the light timer out. Will the lights stillwork? Not even sure it works the lights go out as soon as I shut the door.
Why didn't somebody tell me a 30year old car would have Probs. J/K