VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Dead Short

I have encountered a dead short, I believe. The battery discarges all the way and when charged the ammeter shows discharge. Would someone suggest how to trace this, perhaps where to start.

It would help to know what vehicle. One way to find the problem is to disconnect the positive cable and then isolate the suspect circuits and then add them back one at a time. When you put the positive cable back on the battery there will be a spark. Or you can check with a VOM or battery powered test light or just a test light between the battery post and the positive cable or several options.

I have also done it the way Chipper Dipper suggests, and it works great for finding a shorted circuit!

Thanks for the replies.

The vehicle is a 1940 Chev Special Deluxe Business Coupe. At this point the front fenders are removed so the head light, parking light and horn are disconnected.

After disconnecting the positive battery cable, there should be no continuity between where and ground? That's one of the places I'm confused.

And if I isolate (fix) the suspect curcuit, will there still be a spark when I re-hook the positive cable?

Prior to this problem, while the battery was disconnected, I did remove the generator, then re-install, and then re-hook the battery.

If everything is unhooked or the fuses out then there should not be a spark. If any switch is in the on position then there will be a spark as current will flow. If bulbs are taken out of the sockets, fuses taken out, starter wire disconnected, wires taken off the regulator, etc. then there should not be a spark. If there is one, start looking for a wire that has the insulation off or gets hot! If you have an amp meter with a loop check for current flow. A lot depends on the test equipment that you have available. A light socket with two pigtails and a 6v bulb is all that is really needed but it will take a lot more time. A VOM test meter is much faster as you can check for grounds and continuity. I could not operate without a VOM and they are getting real inexpensive for analog ones (digital for that matter). If a hot line (+) is grounded then all you need is to find where.

Most cases of battery drain are voltage regulators or cut-outs sticking, a radio left on, an interior light on, brake light switch defective, ignition switch left on. I sure would look there first.

Chip...

I found it. It was my non operational radio. It got turned on, probably by a Grand kid, anyway I thought the worst without checking out everything. I will definitely keep the directions for finding a dead short.

Thanks again!
:) :) :)

Big Bob those little ones are really adapt at button pushing and knob twisting aren't they? My wife and I had a mystery oven light several years ago (we didn't even know the oven had a light for years) It would have the light on for a couple of weeks then the light would be out for a couple of week, we couldn't even find a switch, but I watched a 3 year old in the kitchen one day, he walked by the oven reached up under the door handle and pushed a button and Wallah! the light went on, then he walked back into the den as if nothing ever happened!

THE PROBLEM WITH THE RADIO IS PROBABLY THE VIBRATOR. IT LOOKS LIKE A METAL VACUMN TUBE AND IF IT STICKS SHUT IT WILL DRAW TOO MUCH CURRENT AND MAKE THE RADIO DEAD. IF YOU FIND THE METAL TUBE, JUST RAP IT ON SOMETHING HARD AND YOU MAY BREAK LOOSE THE CONTACTS WHERE IT WILL WORK AGAIN.

Thanks Huff,

I'm actually going to have the radio restored, but that will be one of the last things I do...I'm going broke just getting the car back on the road. :) :)