High battery voltage

[anthracitedub]

My 62 has a 1600DP with an alternator... been driving it to work rather than my big truck. This morning I noticed while having all the lights on and a blinker going that the Gen/Alt light was glowing. A bit worried, I went in to work knowing that I would check my belt and my cables when I got home.

I just checked the belt and cables, everything is tight and right. I did a voltage check and my battery has 19.5 volts! I’ve never seen this with an Alt, it has an external regulator I think... here’s a pic of the engine.

I’m mostly a gen/regulator guy... and I plan on going back 6v real soon because I’ve restored a 1200 to go back in the car this winter... but I plan on driving it like it is the rest of the season.

Should I just change out that module that’s on top of the alt body or is there a way to test it/repair it ?

[KTPhil]

[anthracitedub]

No, with the car off... at first it was over 20 volts... then it dropped to 19.5... yeah I don’t understand it... I’m gonna run back out and double check my meter.

Edit: just rechecked, false alarm! My meters batteries are going out... I rechecked and it read 12 and some change right as the screen died out...

That was crazy and my apologies for an unneeded post.

Just put a new battery in the meter and I have 12.5 volts just sitting no engine running.

I wonder why my lights glowing now? It’s never done this with this set up.

[sjbartnik]

If the voltage is high, the regulator is the natural suspect. But also important to make sure the alternator and regulator are grounded properly. If the ground connection is poor the regulator will go high.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[anthracitedub]

Maybe we can make this post more of a PSA to always double check the condition of your measuring equipment. That and make certain you are well rested before you begin troubleshooting or working on machines... it’s been a very long day.

However, I will clean all my main power wires and grounds this week cause Ill have a little time to play and we’ll see if I can get that gen light to turn off all the way.😔

[sjbartnik]

Sorry looks like I wrote my post before your post hit about the meter batteries being off.

So disregard comments about the regulator.

If the battery is fully charged it should read 12.6v with engine off.

The generator light works off voltage differential. It gets power via the ignition switch and grounds via the regulator. So when alternator is not spinning, light is grounded and comes on.

When the alternator starts putting out voltage, it puts voltage on the other side of that bulb. If the power and ground side of the bulb both have the same voltage, then there is no potential there and the light is off.

If the light is glowing softly it's because there is a difference between the voltages on each side of the bulb. This is usually because of corroded connections, bad grounds, etc, in that current path. Check what voltage you are getting at the black wire at back of speedometer vs. the voltage you are seeing at the blue wire at the regulator with engine running.

In an ideal world they will be the same but rarely is the world ideal.
_________________
1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[anthracitedub]

Cool thanks for breaking it down for me.... I’ll go and check those later today and clean the circuit contacts up... I’ve had this setup since 2000... only replaced the battery as needed... other than that, nothing’s changed. It’s been a super nice engine/system.

[herbie1200]

Be sure to set voltmeter for DC measures. If set to AC voltage readings are 40% higher.