Voltage WAY high

[nvonada]

My 41 Champion has the original 6v positive ground system. After reinstalling the engine I noticed the ammeter seemed to be running high so I put a voltmeter on the battery. 19 volts![:0] That can't be good. That was late last night and I had no time to troubleshoot. I was very careful with the voltage regulator but I did paint the firewall and the regulator mounting hardware. Would a bad regulator ground cause this problem? The manual says to send the regulator to an Autolite service center for repair. I should call Autolite and ask them if they still do that.

I just hope I did not blow every light bulb on the car.

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http://stude.vonadatech.com

[jclary]

Good morning. I just logged on and noticed your post. Perhaps someone will post the solution before I type this reply. I have always took pride in being able to take things apart and reassemble them the way they came apart. However, every now and then, I find that I can be humbled by simple mistakes. I once had a similar problem and finally realized that I had switched a couple of wires on my regulator as it was pegging the needle on the positive side. I don't recall the exact wires I had crossed, but when I finally got around to consulting the manual and getting it right, the problem was solved. Take a harder look at your connections. I suppose it could be some internal problem with your gen. or regulator, but check the connections to be sure and that includes the wire connections on the generator as well as the regulator.

John Clary
Greer, SC

Life... is what happens as you are making plans.
SDC member since 1975

[Jeff_H]

Its sort of "impossible" to get 19v on a 6v battery even with severe overcharging. Look for the electrolyte (acid) to be boiled out and the battery dry. There is probably a problem with your charging system too but I wouldn't think it possible to get the voltage to go that high with a good battery.

Jeff in ND

'53 Champion Hardtop

[Bud]

19 volts on a 6 volt system isn't likely as everything in the electrical system would be destroyed in short order. Your regulator most likely needs adjustment but I would suspect there is a problem with the voltmeter you used to test the generator output. I've had issues with some of the new digital meters not reading correctly on a 6 volt system. If you have an analog meter try that. The voltage at the battery should be somewhere around 7 volts when the regulator is adjusted properly and the engine speed is around 1500 rpm or above. Bud

[nvonada]

Thanks, all.

Bud,
I should have thought of the digital meter. I did check with the engine off and got a little more than 6V just like I would expect. But that voltage regulator vibrating away might very well throw off a digital meter while the car is running. My battery charger has an analog meter on it. I will throw that on and try again. I really need to pick up on of those old tach-volt-amp-dwell meters.

I already double-checked the wiring for correct hookup and all the terminals are clean. I really want to get this car drivable for the 4th but if I rush I will fubar something.

Nathan

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http://stude.vonadatech.com

[BobGlasscock]

Electrically speaking, it is impossible to have more voltage anywhere in a circuit than the source creates. This being the case, if your meter is correct (And I have been in electronics for over 30 years and never seen a bad meter) I would do this:

disconnect the hot side connection of the battery and measure the voltage on the terminals.

start the engine, disconnect the hot side of the battery and 1) measure the voltage across the battery, 2) measure the voltage from the disconnected hot cable to ground.

The only option I can see after this diagnosis is the generator. So, if the voltage is too high on the disconnected cable to ground, then look at the generator.

Don't know how to tell you to seperate the generator from the regulator, but that would be a final step to see if the generator is correct or the regulator is correct.

'50 Champion, 1 family owner

[Jeff_H]

Aha! The regulator "vibrating" is likely causing a lot of voltage spikes on the 6v due to the coils in there and possibly the generator being switched on/off while charging. There is inductive kick there. Those spikes can cause troubles for some digital meters with slow update rates. I bet the reading is sort of jumpy too ?

Analog meters are usually immune from this as they basically are too slow in responding to show these spikes.

Jeff in ND

'53 Champion Hardtop

[nvonada]

I used the analog meter on my battery charger and I really don't think I have a problem. The meter has no actual voltages on it, just stupid color bands, but it is in the ballpark. I never thought about the mechanical regulator throwing off a digital meter. Thanks for suggestions all!

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http://stude.vonadatech.com

[Bud]

As an update to the digital meter issue, I tried to test the charging circuit in a 40 Ford yesterday and my digital meter showed 21 volts and was jumping all over the place . I dug out my old Simpson 260 analog meter and that showed the voltage right at 7 volts. Bud

[Buddy1944]

Yes! The regulator has to have a good ground...

Buddy...'54 Champion 2dr
Warner Robins, GA 31088
478-953-3077

[JDP]

When digital meters first came out, as a Navy Electronics Tech, I would not let my guys use them. I still use my Simpson 260. Watch a sailor tying to peak a voltage by watching digits going up and down instead of a swinging needle was just nuts.

JDP/Maryland

[jjones]

Ace Hardware sells an el cheapo analog meter. Tiny numbers that are hard for us old farts to read but otherwise they seem to work fine.


Jeff Jones
Tucson Arizona
1947 M-5