Battery drain
Thread Starter
Heel & Toe
Joined: Mar 2009
Posts: 19
Likes: 0
From: Broken Arrow Ok.
Battery drain
I have a 78 vette. Put in a new battery but if i dont drive it every day the battery goes dead. I took the negetive post off the battery and put a tester beteween the battery post and the cable, I'm getting 12 volt reading on tester with the key off. I'm guessing that something in the car is still on draining the battery. How can i trace it down.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Your 78 has a delay on the courtesy lights that you will have take in to consideration. Here is a test in this thread that should help.
http://forums.corvetteforum.com/c3-g...with-pics.html
http://forums.corvetteforum.com/c3-g...with-pics.html
Thread Starter
Heel & Toe
Joined: Mar 2009
Posts: 19
Likes: 0
From: Broken Arrow Ok.
Thanks very helpful.Did not solve problem. I pulled out all the fuses and wires in fuse panel,tester light still stayed on. Unpluged the harness that goes to the stater light went out. It has to be something that does not go through the fuse panel. Or maybe fuse panel has a short? I dont have any wire stymatics maybe that would help.
Drifting
Joined: Jul 2000
Posts: 1,266
Likes: 0
From: Allen, TX, USA
Doesn't the 78 have an anti-theft system ?
Once a day is a little excessive. But if you fix that you may still want a battery
tender, or a disconnect switch. Harbor Freight has the side post disconnects.
Once a day is a little excessive. But if you fix that you may still want a battery
tender, or a disconnect switch. Harbor Freight has the side post disconnects.
Instructor
Joined: Sep 2009
Posts: 135
Likes: 2
From: Waterbury CT.
Hook up an amp meter between the battery and cable. Battery drain is measured in amps, not volts. Shut everything off and close the doors. The amp meter should go all the way to ZERO in about 40 seconds. If you have a reading of 1/2 amp or more; look for a bulb that is on.(glove box, hood light etc.) If your reading is about 1/10 of an amp then look for electronics that are putting the drain on your battery.(Key warning/ seat belt buzzer, radio)Mine was the buzzer. Start by pulling fuses that are always hot with the key out of the ignition. This will locate the circuit that's bad. Remember to close the door after you remove each fuse and let the interior lights time out. Now get an electrical diagram to show you all the items in that circuit . Good luck.
Steve
Steve
Melting Slicks
Joined: Sep 2007
Posts: 2,387
Likes: 123
From: CA.
Hook up an amp meter between the battery and cable. Battery drain is measured in amps, not volts. Shut everything off and close the doors. The amp meter should go all the way to ZERO in about 40 seconds. If you have a reading of 1/2 amp or more; look for a bulb that is on.(glove box, hood light etc.) If your reading is about 1/10 of an amp then look for electronics that are putting the drain on your battery.(Key warning/ seat belt buzzer, radio)Mine was the buzzer. Start by pulling fuses that are always hot with the key out of the ignition. This will locate the circuit that's bad. Remember to close the door after you remove each fuse and let the interior lights time out. Now get an electrical diagram to show you all the items in that circuit . Good luck.
Steve
Steve
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Horn relay or alternator are the only electrical items that get battery power WITHOUT going thru fuses/breakers. They have fusible-links which still can carry current when ignition is OFF.
Disconnect 'hot' wire on alternator (cut battery first!) to start, since that is the easiest to check. You could have a failed diode in the alternator which is leaking current 'backwards' (rather than blocking that current flow).
Disconnect 'hot' wire on alternator (cut battery first!) to start, since that is the easiest to check. You could have a failed diode in the alternator which is leaking current 'backwards' (rather than blocking that current flow).
Safety Car
Joined: May 2004
Posts: 4,350
Likes: 1,578
From: los altos hills california
