Battery drain, possible short problem?
Thread Starter
Racer
Joined: Jul 2001
Posts: 331
Likes: 1
From: ny
Battery drain, possible short problem?
My '68 has had a problem for a long time now. If I drive it and let it sit a couple hours I have no problems but every time I get up in the morning to start it the battery is totally dead. I put the charger on for 2 seconds and start it and shut it off, then restart to check it and battery is fine. How do I go about looking for the problem? Which fuses are supposed to be hot with the car off and key out? When I check, almost all the fuses are hot with key out. Is this normal? Any way to use some kind of tester to find the problem? This is driving me nuts!
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
Re: Battery drain, possible short problem? (james75)
I had a similar problem with my 74 and tracked it down to the light in the rear storage compartment. It stayed on even with the lid down. Replaced the switch and all was well. Probably the best way to check for drain is to remove one fuse at a time and let the car sit overnight. When you get up one day and the car starts it's in the circuit that the fuse serviced. Not too technical but it will work. Hope this helps. :chevy
Le Mans Master
Joined: Dec 2000
Posts: 5,245
Likes: 25
From: Blue Ridge Georgia
Re: Battery drain, possible short problem? (vettfixr)
If you can't find the short there is another way to help this problem. The Sears Security Battery has a circuit that if it detects a constant drain it will shut down the battery. I have the same problem, every time I want to use the Vette and it has set for a day or more I have to use the clicker to turn the battery back on. At least with the Security battery you know it will always start.
Pro
Joined: Feb 2000
Posts: 741
Likes: 46
From: Hebron IN
Re: Battery drain, possible short problem? (james75)
Seems like the battery is draining pretty fast.
I had that problem with my '75 but it took 3 to 4 days of sitting before the battery went dead.
The center compartment in back has a light in it. I lifted the lid and the light never worked so I ruled that out. Few weeks ago I opened the tire jack compartment and noticed a light was on. Opened the center compartment door and the light went out. Push the switch in and the light turns on! The plunger was kinda crunchy so something broke internally in the switch causing it to do the opposite of what it should. It's a long shot but it's worth checking out.
Battery cells do short out, especially on cheap Walmart or Autozone brand types. Charge the battery and let it sit overnight disconnected. If it's dead you know it's the battery.
George
I had that problem with my '75 but it took 3 to 4 days of sitting before the battery went dead.
The center compartment in back has a light in it. I lifted the lid and the light never worked so I ruled that out. Few weeks ago I opened the tire jack compartment and noticed a light was on. Opened the center compartment door and the light went out. Push the switch in and the light turns on! The plunger was kinda crunchy so something broke internally in the switch causing it to do the opposite of what it should. It's a long shot but it's worth checking out.
Battery cells do short out, especially on cheap Walmart or Autozone brand types. Charge the battery and let it sit overnight disconnected. If it's dead you know it's the battery.
George
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Re: Battery drain, possible short problem? (vairxpert)
You have a 68? Simply remove the fuse to the windshield wipers.... problem solved!! 
That's my best guess, but the scientific way is to disconnect your negative battery cable (I guess you could use the positive side) and run a test light between the battery terminal and the cable. If the light goes on, then somewhere you have a completed circuit. Then you start pulling fuses one at a time until hopefully the test light goes out. Make sure the car door is closed when you do this, or your interior light will be on and you will get a "false positive" test.
I would check the wipers first. 68s have power going to the wiper motor fulltime. The wiper switch grounds the motor. Inadvertent grounding is a common source of drain problems. Also check to make sure the wiper override swich under the dash is not in the "on" position. This will drain the battery by design (!!) as mentioned in your owners manual. MJ
That's my best guess, but the scientific way is to disconnect your negative battery cable (I guess you could use the positive side) and run a test light between the battery terminal and the cable. If the light goes on, then somewhere you have a completed circuit. Then you start pulling fuses one at a time until hopefully the test light goes out. Make sure the car door is closed when you do this, or your interior light will be on and you will get a "false positive" test.
I would check the wipers first. 68s have power going to the wiper motor fulltime. The wiper switch grounds the motor. Inadvertent grounding is a common source of drain problems. Also check to make sure the wiper override swich under the dash is not in the "on" position. This will drain the battery by design (!!) as mentioned in your owners manual. MJ
