Incipient battery drain

larryswanson · Post by **larryswanson** » Fri Sep 30, 2016 11:18 pm

My M38A1 Jeep has a small electrical drain even with everything off. I see no lights on etc. I understand that the starter switch or the headlight switch sometimes cause this. Does anyone know of any other likely culprits?
Larryswanson

oilleaker1 · Post by **oilleaker1** » Sat Oct 01, 2016 6:47 am

The 24 volt regulator has a capacitor inside that will discharge and show a small spark at the battery cable when connecting the cable. If you put a test light between the disconnected + cable and positive post and it lights up, you have a short in the system. Sometimes a alternator can have a bad diode going to ground which will do this. If you do have a light on, disconnect power leads going to each circuit, one at a time, and watch the light. When it goes out, you found the one to look into. John

skyjeep50 · Post by **skyjeep50** » Sat Oct 01, 2016 7:22 am

If you do a "search" for other posts dealing with battery drain you can come up with some other ideas of what to check. Here is one post of interest:

http://www.willysmjeeps.com/v2/modules. ... rant+drain

I've also read that people have had shorts develop in the ignition switches. Test each circuit and you will find the culprit.

BCA · Post by **BCA** » Sat Oct 01, 2016 6:02 pm

Carbon build-up in the starter switch can cause a power drain. A battery kill switch, located where it is handy to use, is a good safety feature as well as a solution to current drain when parked. .. Brian

Hawkshadow · Post by **Hawkshadow** » Sun Oct 02, 2016 7:43 pm

Check your batteries to see if they are "see-saw" draining. I forget the term right now but if they aren't paired one will drop to charge the other, which will in turn try to re-charge the first once it's higher and the see-saw goes back and forth slowly draining the batteries.

Post by **wesk** » Sun Oct 02, 2016 9:12 pm

It's called chasing and happens when the capacitance of the two batteries differs significantly usually due to a variance in age or unequal loading as is often the case when folks try to tap 12 volt off of only one battery for a 12 volt accessory. If you are one of those folks try alternating which battery you make the tap on.

Troubleshooting is really very simple. Disconnect +24 cable or the ground cable that bolts to ground and place a test lamp in series between the battery and the disconnected cable. If that lamp glows you have a short or power loss to ground. Then you disconnect one circuit at a time until the lamp goes out and you have found the offending circuit.