My battery keeps getting drained after about 2 days of sitting up. What's best way to find the problem?

I have removed all of the fuses that have power when the ignition switch is off, but the battery still goes down. It's a brand new battery.

 

test the alternator diodes and see if they are draining it. if everything else is unplugged that requires volatage i would then say something is grounding causing the draw. (solinoid, Battery cable chaffed, alt diode etc.) there is actually only 1 thing on these cars from 79 down that requires power after key off and that would be memory for a radio or aftermarket equpi.

 

Click on this link and roll down to post #5.If you have questions about the test let me know.
http://forums.corvetteforum.com/c3-g...-drainage.html

 

An expedient way of testing out the alternator diodes would be to just disconnect completely the alternator.

You should thinking about getting a volt-ohm-ammeter. You can get some rather sophisticated digital read out voa's for around $80, but something cheaper will probably do the trick.

with the battery charged up, and everything off put the voa in series with the positive connector of the battery. Set the voa to an amp or milliamp position and read current discharge from the battery. Make sure the doors of the car are closed. Do this with the altenator completely disconnected. Then reconnect the alternator and see if the discharge current is different. You should see only a few milliamps for your clock and radio memory circuits.

Here's two things that caused me to have battery discharge fits; (1) a light inside the center storage compartment that was always on. I discovered this by looking in the car when everything was dark. I could see light leaking from the compartment door. (2) My 68 windshield wiper motor would sometimes spontaneously come on when the car was parked in the garage. I knew this because I ultimately discovered the wiper blades were jambed up against the windshield wiper compartment door (no such doors after 1972).

Also, if you want to go to the trouble, I'd suggest looking for the short/discharge source with dry cell batteries that add up to 12 volts. I myself have bought a 14 volt 10 amp power supply to check out electrical problems. Using the battery can be dangerous since a fully charged healthy battery can pump out 800 amps for a few seconds and do serious damage.

Finally, once a lead acid battery becomes completely discharged; i.e. really flat, it looses about 30% of its capacity even if it was a new battery before it was allowed to flatten itself. If your new battery has become completely discharged several times, the battery is damaged.

 

Thanks for the link... been thinking I might have a drain also (keep it on the trickle charge), this will help

 

Roger......did you lose the link to the paper I made for you?

http://photos.imageevent.com/durango...%20Testing.pdf

 

Yes I had a computer melt down thats why I have the new laptop.I tried to copy this awhile back and it wouldnt work for some reason but kept forgetting to ask you about it.I'll copy this one and then make sure it works.Thanks again Matt.

http://photos.imageevent.com/durango...%20Testing.pdf

EDIT--Kool it works...Thanks Matt

 

I discovered my battery will drain in about 4 days if I have the heater/ac fan in the ON POSITION when I shut the car off! That's crazy, but discovered quite by accident that that was causing my drain. Until I really want to solve that problem, I have to make sure I have the heater/ac control in the off position before shutting off the engine. I had to have a fuseable link replaced last winter and I believe it might have been done incorrectly because that is when it began happening.

 

Do your wipers work ok? Take a test light and see if the case on your heater blower motor is hot or the case on your wiper motor is hot.If so the ground for the wiper and heater were put on the pos terminal of the solenoid rather than grounded to the engine.

 

Guys, I just joined this forum yesterday. This is the best information/help I could have imagined. I have an ohm meter and will start checking things out this afternoon when I get home.

With regards to my battery - it's brand new but has been totally drained now, at least 2 times. I will replace after I get this problem sorted out.

With regards to my windshield wipers - I have a new windshield wiper motor, and a new switch. However, once while I was driving down the road the windshield wipers came on long enough for the wiper blades to make one pass and go back down. I thought that was very odd.

My fan blower for a/c and heater works, but works very weak. I will check the grounding of these items to make certain they are properly grounded.

Thanks to everyone for the help.

 

Couldn't wait any longer. Used my lunch hour to go home and check a few things.

1. The ground wire at starter is attached to the engine block, not the starter solenoid.

2. Using a multimeter, connected between the battery and posotive battery cable I measured the amperage. With the door open so the console lights are on, it draws 4.5 amps.

2A. When I close the door the amperage drops to 0.2 amps. I disconnected the altenator and there is no change in the amperage, it''s still 0.2 amps.

2B. I removed all 4 fuses that are energized with the ignition off. Amperage drops to 0.0amps.

2C. I replaced 3 of the 4 fuses that are enegergized with the ignition off. Amperage remains at 0.0 amps.

2D. When I install the 4th fuse (works the clock and courtesy lights), the amperage returns to 0.2amps. Certainly this is the circuit that's causing the drain. My question, is 0.2 amps enough to drain the battery in 2 to 3 days? This evening I will unplug the clock and see what the amperage is.

Just for verification I also unplugged the a/c heater blower fan. It didn't change my readings.

I also pushed in the door ajar switches all the way, and the courtesy light switches to see if maybe they were cuasing the problem, but that didn't change my readings either.

One intersting thing I did that I don't understand - I connected the ground lead for the multimeter to my engine block, then touched the other lead to the windshield wiper motor housing and got a reading of 0.18 volts. Is this normal?

 

Might be the courtesy light timer.

 

Sounds like you traced the draw down to the courtesy light circuit.Lots of items that can draw to look for on that circuit.Clock is a common draw.Cant remember if the center compartment on your 76 has a light in it,but make sure you pull the bucket that is above the jack and look below for the wires...sometimes the bulb assembly falls through the hole.
On the 1.8 volts....that doesnt sound right, sounds like a bad ground but only if you are getting that reading while the wiper switch is on.I'm no electrical engineer so since I've never tried using a multi meter to test that I will go out and try it.Be back in touch.

 

Matt do 76s have the timer?Thought 77 was first year.Hmmm something else to check.

 

I thought it was either a late '76 addition as an early '77 addition. It was worth a mention even if I am wrong and he doesn't have one.

 

well ya know it isnt the clock draining the battery. heck half the timeit doesnt work anyways. so you found that the courtesy light circuit maybe the problem. if it does have a times that would be the first thing to think of as they go bad ALOT! but also it could be something simple like the compartment light if there was one or the glovebox light being left on.

 

Definitely worth looking at.


roger3---Took a voltage reading like you did from the block to the wiper case with the key off and got 0.Did it with the key on and blower running on low and got .018 not .18 or wow the 1.8 I posted.Decimals kill me.
Thought that was interesting and turned the heater blower switch from low to medium and the voltage went up the higher.High position went up to .034.Pulled the ground off the blower and reading went to 0.Bet if I grounded the blower really good you could keep that reading at 0.

Now the question is did you get your reading with the key on or off?

 

My clock does work. I rebuilt it with an aftermarket kit. Makes me suspect my work. I will unplug the clock and see if that changes the amperage reading.

I do have a light in the center glove box compartment. I will check it to make sure it's going off when the lid is closed.

What does the courtesy light timer do?

How do I determine if I have an early or late 76 model?

 

I'm sorta guessing its the glovebox but you never know.
On your clock statement...thats how these clocks go bad... the points stick and they draw power all the time rather than what you said some of the times.

 

All of my readings were taken with the ignition key off.