Help with parasitic battery drain.
Thread Starter
Cruising
Joined: Mar 2017
Posts: 14
Likes: 0
From: Bentonville Arkansas
Help with parasitic battery drain.
I have an 81 corvette with new crate motor. I have replaced the alternator and battery twice. Battery keeps dying overnight. Where do I start to track down whats killing my battery?
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Charge the battery, then start pulling fuses one at a time. Check your headlight switch is not in the "Courtesy" light position. Check the cigar lighter is not pushed in and stuck. Check the horn/relay is operating properly. Make sure that a courtesy light (like in a storage compartment) is not staying on..
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
with Tim. Most quality digital volt meters can withstand a 10 amp draw for a short period of time. So you put the meter between the Pos battery cable and the battery. put it on the 10 amp DC scale and see what the draw is. If it spikes over remove it. If it is a smaller less than a few amps you can do the removing fuses routine till it drops to zero.
Another better choice is to take the battery out of the loop and set the charger to the 2 amp setting and see first what the draw rate is before ever using the meter.
I personally have a .3 amp drain or 300 milli amp constant drain with my aftermarket digital multi spark and MSD E-tech ignition. My cure was a battery disconnect switch.
I hope this helps!
If you have run a battery to "Zero" a few times they never really recover
Racer
Joined: Mar 2014
Posts: 316
Likes: 39
From: Machesney Park IL
I am old school. I disconnect the negative cable and put my test light between the post and the cable. Usually, if you have a draw, it will light up almost as bright as a dome light. Then I pull fuses and watch for the light to dim. Might have to disconnect alternator too. On my car, it turned out to be the courtesy light timer, mentioned above. We always allowed 50 milliamperes draw, or less as acceptable. When the test light goes dim, but still can be seen, then I get my ammeter out to check it.
