The Stovebolt Site Forums The Shop Area The Electrical Bay Hooked up 12 volt charger to 6 volt battery

Well the switch on the charger was set to 12 volts and I hooked it up to the 6 volt battery. It was only on a few seconds, but now my ammeter does not show positive charging with the engine running. It will show a negative draw if I switch the ignition on without starting. What did I do? 1940 chevy.,

Thank for the help.

Maybe the reason you had to use the charger was that the system wasn't charging in the first place. Maybe you did nothing, but check the voltage out of the generator and then out of the regulator.

I agree with Baldy. It sounds like a charging issue to me.

When you wind up the engine, does the ammeter show a charging state? It's not unusual for an ammeter to show a "barely charging" state on idle.

When you have the engine running, does the ammeter show a closer to center reading than when you have the truck on but not started?

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I don't think that you've fried the battery, because you're getting a negative reading on the ammeter -- which means that whatever you're running is drawing from the battery and not your generator/regulator setup.

I can't speak for the rest of the system until I've got some more information.

Something to remember is that the ammeter will show a greater discharge if the engine is not running and the points are closed with the ignition on than it will with the engine running and no output from the generator. In the latter case you get a sort of RMS value, so it can appear that something must be coming from the generator.

There will be very little charge on the ammeter if the battery is fully charged. The best way to check it is with a voltmeter. It should run up to about 7 volts when you rev the engine a little. You can check it with the dash gauge. Turn on the lights &/or other acessories & rev the engine. The gauge will show discharge at idle & come back up to charge when you rev the engine. If it stays at discharge you have a problem with the charging system.

I did the same thing with my charger. The charger melted, toast. But my fairly new six volt battery is fine. You have some other problem.

put a load on the system,ie. turn you headlamps on for about 10 min. with out the engine running.
Then crank the engine and look at the guage. Does it charge now?

I turned on the lights for 15 min, started her up, no charging on the ammeter. It shows a draw, but no charging, I'll check the volatage reg and gen outpt.

Ok with the engine running give the regulator a sharp rap with a rubber hammer. Maybe the darn thing is just stuck.

I tried to check amps from the bat on the reg but my mulimeter jumps from .5 to 18. I checked the points in the regulator and all seems ok. maybe I cooked my ammeter? But would it still read a draw if I cooked it?

The ammeter in the cab shows slightly more discharge with the ignition switch on, motor not running than when the motor is running.

I explained that earlier in this thread. Check volts at your generator and regulator, not amps.

Volts at gen about 6, volts at reg bat terminal 0

Years ago I made the same mistake on a positive ground f*rd flathead with 6 volt system. I had to re-polarize the generator. Briefly (less than 2 seconds) touch a piece of wire between the "bat" and the "arm" connections on the regulator.

Sounds as though the regulator Bat terminal is not connected to the negative side of the ammeter.