The Stovebolt Site Forums The Shop Area The Electrical Bay Leaking current, killing battery

Hello Electrical helpers. I have had a recurring problem killing battery overnight. Obviously I can not find an accessory on, and this is a simple truck. Recent rewire job. Everything was fine. I plugged in a battery charger this morning and it chargers for 2 minutes and then the circuit breaker inside the charger pops. 10 seconds later it tries to charge again and pops 10 second later. So it would indicate I have a strong leak or short. I pulled all the fuses and the action by the charger is the same. I checked my connection on the starter and it looks ok. How do I track down the short with my test light or meter? Thanks for any help. Doug

you can put your meter or test light from the disconnected + cable to the battery pos post and see if there's actually a current flow with everything turned off - also disconnect the battery to see if it will take a charge by itself, isolated from any wiring, might be a bad cell

Bill

Hang on, I disconnected the positive side of the battery and the charger still does the same thing. What the heck? Could this battery be cookieputz? New 2 weeks ago

Sorry jumped your post. I will check that

yes a new battery can be defective - take it back to place of purchase or to a shop and have it load tested - some parts houses will do it, or a good auto electric shop

Bill

Did you mean the negative post? Sorry I don't quite understand how to check for current flow when everything is off. Please explain again. Thanks

positive post usually, although neg should work - just complete the battery circuit [positive terminal to the disconnected cable] with the meter so you can see if there's a draw on the battery with everything turned off

Bill

I checked v between + post on bat and disconnected pos wire and I have full batt voltage. Everything in/on truck is off. Is this right or wrong?

check current not voltage - but if you're measuring a full 12 V in line, [not from post to post or positive to ground] you've got a dead short someplace and should show a high current flow - a test light will light brightly in that case

Bill

Yes, test light burns semi bright. So leaving it hooked up I took each fuse out individually. No change. Does this indicate my short is ahead of the fuse panel? I have tried wiggling wires. Not sure how to track this down. Any tips?

I would suspect the starter - where the battery connects to the starter [big terminal] there should be another wire that goes into the harness to the cab, disconnect that wire and the one from the side terminal into the harness so that the only thing possibly still connected to the battery is the starter .... if this is a foot start, the box on top with the button that gets pushed may be defective

Bill

Finally got my tester to read 10 amps (seems like a lot) across the positive wire to pos term on battery. Any tips how to trace for an active circuit that should not be active?

Additional info: I was able to determine that I have voltage (about 4 volts) on the unswitched side of the fuse panel. And of course that leads back to the Batt port on the ign switch. In my case I have 2 heavy leads on the Batt terminal. These both go to the fuse panel( I think).

i will now look again at the starter. This is a key switch 1955 task force. I put in a painless wiring kit. Not painless now!

Bill, on my starter there is the heavy lead from bat to heavy post on starter sol. Also a purple (colour likely irrelevant) that goes to harness to ign switch sol. With the heavy wire is a 10 gauge wire......trying to check my book where that goes. I think it goes to 70 amp fuse then to fuse panel?

So what you are saying is disconnect purple and see if "voltage drain" with everything off continues? Thanks. Doug

Sorry, more info. There is voltage at the large terminal on the alternator. That is all off, no key switch. Does that help my diagnosis?

well, that's a whole new can of worms, nothing stock ... the 'painless' wiring kit should have some kind of wiring diagram, the factory one won't be accurate now ... on the key start solenoid the purple wire should go to the ignition switch, it feeds the coil - if you have something close to the original V8 key switch this is the wiring - the 2nd heavy wire on the starter should go to the alternator [or regulator if it's an externally regulated alternator], which would be why you have voltage showing at the alternator

try disconnecting the purple and see if there's a change, then disconnect the heavy wire [that likely goes to the alternator] and see what happens - could be something in the ignition or charging circuits - you also want to find out where the fuse panel gets power, most anything fused [except the light switch] should get power from the ignition switch so that everything turns off when the key is off - not sure I'd want a 70 amp fuse anyplace on the truck, there's nothing that would blow that, but if it's in the main battery feed, then if it went you'd have no power anyplace including lights or ignition - and any individual accessory should have it's own individual fuse

Bill

IF the battery is fully discharged this could easily be the reason your charger is tripping out - short n sweet it is OVERLOADED by totally dead battery.
SOLUTION put a pretty good battery across charger and charge for 30 minute. Turn off and parallel bad battery onto the good one.
Expect some arc n spark - let sit for 10 minute. Turn charger on. The reason this works is the good battery is sharing the load thus unloading (partially) the charger.

Now to find your ground ie short or really a partial short.
1. Disconnect one side or other of battery preferably the non grounded side.
2. Pull all fuses check for current. IF gone reinstall one fuse at a time and check for current.
3. Break apart the starter solenoid connections and reconnect one - checing for current each time.
4. It should show up on one of the wires. 5. Start hand over hand tracing.

Dan Bentler

Hi Dan, you were right on the Batt Charger. I trickle charged it for 10 hours to bring it back. It was really pooched. Now I am working my way through the wires. I will let you and Bill know how it goes. Doug

Bill and Dan, problem was a faulty alternator. All fixed up now. I'm happy and back to the next thing on the list. Thanks for your help. I will be sending new questions soon! Regards Doug.