The Stovebolt Site Forums The Shop Area The Electrical Bay 12 volt battery drain....

Just recently completed a 12 volt conversion w/ generator and wire harness swap. Everything was working good. Today, I disconnected the battery to install steering wheel and horn.

Apparently I disconnected the positive cable to the battery and left the ground/ negative hooked up. This was accidental, I usually disconnect the negative and leave positive hooked up.

After 4-5 hours like this, my brand new battery was dead.

Any idea why the battery drained so quickly?

There is no reason why disconnecting the positive cable instead of the ground should drain the battery. An open circuit is the same no matter where the disconnect is made. Have somebody recharge and load test the battery- - - -chances are your "brand new battery" is a brand new piece of junk!

Load test- - - -load the battery to 1/2 the cold cranking amp rating for 30 seconds, then check the battery terminal voltage with the load still on the battery. The voltage should not drop below 9.6 volts. Example: A 550 CCA battery gets loaded to 275 amps for 30 seconds. The specific gravity of the electrolyte should be at least 1.250 in all 6 cells before testing. Full-charge specific gravity should be 1.250-1.265.

Good luck!
Jerry

sounds like a brand new defective battery, there's no way you could kill the battery with only the ground cable connected .... unless you had something shorting the positive post to ground - disconnected the cable at the battery or at the starter?

Bill

It was disconnected at the battery, didn't come into contact with negative post- doesn't reach.

I have the battery on a charger for the night.
It is a cheap battery.

Battery is dead. May it rest in peace. You might get it working with some time on the charger and a head light works just fine to discharge when you need to cycle it but...I would not want to depend on it.

I think your right, the battery was left on the charger over night.
And it only charged to 6 volts.

Update:

Brought the battery back to my FLAPS, and they charged it back to 12 volts on their charging system. I guess my little charger couldn't handle it. Installed said battery, turned the engine over about a dozen times and battery dead again. Exchanged the battery for a new one now.

With new battery installed, still had no spark at plugs. After checking the ignition system, I found that my coil (Pertronix, 1.5ohms) was toast. After removing this coil, I could see where oil is trying to escape around the positive post, its fried. Installed a new 12 volt coil (same pretronix, 1.5ohms, internally resisted) and all is good once again.

I am now thinking that I left the ingition switch in the 'on' position, while I had the negative battery cable unattached, for 4-5 hours.

I still dont understand how this would have cooked the coil and the horn, horn doesn't work any longer either.

the switch on with the battery disconnected didn't fry anything, but with the battery connected, it could cause the coil to fry if the points happened to be closed, you may have had the key on for a while before or after the battery was unplugged .... the horn could be a bad connection, track individual problems, don't try to lump things together

Bill

That makes more sense.

Ya the horn may have had enough with the 12 volts to it finally.

Is it normal to have power to the horn with the igintion off?

yes, the horn normally bypasses the ignition switch, too much current ... and yes, 12V on a 6V horn could have fried it

Bill

Thanks red58