VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Battery Voltage - 6 Volts

I had a dead battery the other night and did a push start and got home fine. In the morning after placing the battery on charge and starting the car up (a 1940 216). I decided to check the battery voltage at static and running just to see if it is charging properly.

I got 6.28 volt static (not running) and 8.44 volts (Running) readings were taken at the battery terminals.

Are the above readings normal ?

Thanks,

Wes Marquis

These voltages seem pretty good. Check your service manual for the charging (running voltage) as it should provide a range. From experience, a couple volts above the rated battery voltage when running is about right.

If you've just had a charger on your battery, check your battery voltage (engine off) after sitting overnight OR after putting the headlights on for 10 seconds and then turning them off. This will remove any "overcharge" from the charging so your reading will be more accurate.

The big question: What happens to the charging voltage when you start turning on some accessories like the headlights when the car is running? I'm not sure at what point the generator will have trouble keeping up on this car but if you try one accessory at a time, you may find one circuit drawing lots of power.

It's possible that either the battery or generator is weak or there is a bad electrical connection so the increased load from the ignition, etc while driving might cause your problem to recurr...

A cheap battery load tester is handy for some quick testing of the battery state or you could get the battery tested at a auto parts store (I think they can do 6v batteries still?)

If you are handy with the meter, you can also measure the current to see if there is current being drawn when EVERYTHING is turned off including the engine. Disconnect the positive terminal and connect your meter between the Positive terminal on the battery and the now removed battery cable (if your meter can measure "Amps"). Obviously with everything turned off there should be no current.

Thanks CanadainTim, I'll give your suggestions a go....

Wes

If you haven't already given it a shot, I would advise calling auto parts stores before lugging a battery around. I've had no luck finding one with a 6-volt tester or charger. They'll just take it to the back and bring it back and say it's no good--without having tested it. I've had mine tested at an old-school auto electric shop or some other business that does business with farmers. I frequently read posts to the effect "oh, you can still get many parts at your local (fill-in-the blank) auto parts store," but folks, it ain't so in Central Texas. Good luck.