Overvoltage

[Wedgetail]

I took my ‘40 Deluxe out for a quick drive to try out the wheel alignment. After about 1/4 mile it started running really rough, lost most of its power and the battery gauge pegged high, and the coolant temp pegged low. (Oil and gas gauges were ok). I limped home, and in the garage, revving the engine causes the battery to get over 8 volts (and the headlights brighten with RPM). Until recently, I wasn’t even convinced that the generator was charging the battery, and I’ve never seen anything over 6.3V. Why all the voltage?

[deuce_roadster]

I would suspect the V reg.

[koates]

With the engine revved up a bit you should be reading 7.3 to 7.5 volts at the battery terminal on the voltage regulator. Set your multimeter on DC Volts, not AC. Regards, Kevin.

[Wedgetail]

Previously, I had never seen anything above the low 6’s and wondered how the battery stayed charged, now I’m seeing over 8. Sounds like it’s time to try a new regulator.

[fortyfords]

And good luck on finding a good USA regulator, if it's the original regulator, take the cover off and clean the contacts and see how it works then.

[Wedgetail]

Sponsored Links (Register now to hide all advertisements)

It’s not the original, it says “Allstate” on the cover. I took the cover off and cleaned all the contacts, and it didn’t make any difference. I have a new one on order from Dennis Carpenter, we’ll see how that works.

[koates]

Maybe its not your regulator at all and the generator is not making enough volts. No use just guessing and swapping parts. To test the gen just remove the field wire from its reg terminal and connect it over to the armature terminal on the reg. Rev her up a bit and your voltage at the battery terminal on the reg should go quite high (over 8 volts) if the generator is OK. If you still dont get above 6.5 volts then the generator is faulty. Regards, Kevin.

[Bill OH]

Use an analog volt meter - a digital voltmeter will give a false reading because of ignition interference. Remove regulator cover, connect voltmeter to battery term on reg and adjust the spring tension on the voltage control opposite the field terminal to 7.2 volts. Try that.

[solidaxle]

When trouble shooting, I go for the easy things first. Try polarizing it.

[solidaxle]

Originally Posted by Bill OH

Use an analog volt meter - a digital voltmeter will give a false reading because of ignition interference. Remove regulator cover, connect voltmeter to battery term on reg and adjust the spring tension on the voltage control opposite the field terminal to 7.2 volts. Try that.

People look at me funny when I break out my old Simpson 260. I love it.

[petehoovie]

Originally Posted by solidaxle

People look at me funny when I break out my old Simpson 260. I love it.

[rotorwrench]

What meter were you getting the lower voltage readings on? Does your 41 have an Amp meter or a Battery meter in the dash. If it's an Amp meter then it may have a short some place. That would play hell with the charging system and could do damage. A short will generally pop the circuit breaker but I have no idea if your car is still all stock or not.

The voltage regulator maintains the voltage as was mentioned in the 7.2-volt range if it's working properly. Low voltage is a sign that it wasn't working properly. There is also a current limiter in the VR box as well as a battery cut out. If the battery was managing to barely charge then it was set so low that it's a wonder that the cut out let the generator even come on line. The cut out doesn't come on line until the voltage in the generator is higher than the battery voltage. That's usually around 6.6-volts. I'd be wondering about the accuracy of the volt meter. If it was accurate then the voltage regulator control unit was likely needing a change some time ago.

[Wedgetail]

It’s a 1940 deluxe with the original dash gauges, so the battery gauge shows voltage, and I’ve calibrated it with a digital volt meter. I don’t have anything as classy as the Simpson shown above. The gauge used to hang out just between red and orange, which was low 6’s, and when it pegs high, that is 8+ on the DVM. The dash gauge is slow to respond (being based heating a resistor), but seems remarkably consistent. I think you are right that the regulator was running low before, and has now given up the ghost. The new one has just arrived in the mail, so that’s the next step. (I know the generator works because I’m seeing the high voltage 8V even without disconnecting it from the circuit).

[Wedgetail]

Update: I replaced the voltage regulator and I’m still having the over voltage problem. When I rev the engine, I can get the battery voltage to get up to 9v, which is obviously too high. When the engine is at idle, it comes down to 6.4v. I am reading the high voltage both on a digital multimeter, and on the dash gauge (battery voltage) which is laggy, but I trust it.

[drolston]

If you are useing one of those resistance type after-market temperature sensors, that would account for why the temp gauge runs toward cold when the voltage is too high.


But regading your over-voltage situation. First, get an analog volt meter; I love my Simpson 260 as well, but you can get cheapo unit that will do the job. Second, are you double-damn sure the regulator you got was for a 6 volt car and not a 12 volt car?

[koates]

You will see high voltages in your electrical system if there are bad high resistance connections in the main battery or earth cables or the main charging cable in the wiring loom. Also just because you have a new voltage regulator does not guarantee that it is set correctly or of a good quality like the original FORD regulators. There are several adjustments inside the regulator, the cut out. the current regulator and the voltage regulator. Take your car to an auto electrician who has been trained how to do these tests and adjustments. The ordinary layman does not have the knowledge to do this. Just swapping around components is not the way to fix problems. Regards, Kevin.

[flathead48]

Be sure generator is grounded to regulator & regulator has proper ground to firewall