Voltage Regulator - Beetle

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No More Landy
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Voltage Regulator - Beetle

Post by No More Landy » Tue Jul 30, 2019 12:12 pm

Yesterday while driving in the rain with headlights and wipers running I noted my generator light came on dimly and then noted a burning smell coming from somewhere. I killed the lights immediately and drove a bit further and tried the lights again and all was good. Generator light stayed off.
Tested the battery voltage this am and 12.8 V. Started up and tried the lights and then noted the voltage sometimes dropping for a few seconds right down to 10 and then back up to 13.8 without me turning the lights off. I see a small resistor wire at the back of the regulator that has the signs of getting warm as the bakelite mounting looks a little discolored/melted. Is it probably the regulator that needs replacing ?Image

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Re: Voltage Regulator - Beetle

Post by No More Landy » Tue Jul 30, 2019 1:12 pm

So I did a quick test drive with my multimeter plugged into the small oil pressure gauge lamp circuit and drove around the block. When I drive with the park lights on I read up to 14 V at full revs and idles at 12.8. After putting on full beam the volts drop to 11 and don't recover much more than 12.5 V after I drop to dips.
When I stopped and checked at the battery itself and held the meter hard against the terminals I get 13 V on idle and max 14V with slight revs, and when light's on normal beam she sits at 12.9V at idle and slight revs at 14V. Seems there is a drop in the wiring somewhere as I know all my earth straps are good as I did them all a short while back. Bit stumped now.

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Re: Voltage Regulator - Beetle

Post by No More Landy » Tue Jul 30, 2019 1:16 pm

Just realised my mistake, the lamp circuit for my gauge goes via the resistor in the headlight lamp dim switch for the instrument lamps.
Idiot !!

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Re: Voltage Regulator - Beetle

Post by retrovan » Tue Jul 30, 2019 1:28 pm

Sounds normal to me

Could just be that your battery was very low on charge putting a big load on your voltage regulator.

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Re: Voltage Regulator - Beetle

Post by No More Landy » Tue Jul 30, 2019 2:00 pm

Thanks Herman

Did another test run with my meter connected this time to my oil pressure gauge +&- terminals and all seems good. Headlighs on full I get 13.8V and when idle it drops to 12.4V.
Headlighs off she hits 14.4V while driving and also 12.4 @ idle.

Can it be that the rain through the boot lid breathers wet the alternator which I see is open at the top and caused a problem last night and now is fine?

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Re: Voltage Regulator - Beetle

Post by 73type2 » Tue Jul 30, 2019 2:18 pm

No More Landy wrote:
Tue Jul 30, 2019 2:00 pm
.. the alternator which I see is open at the top ...
Don't you mean generator?

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Re: Voltage Regulator - Beetle

Post by No More Landy » Tue Jul 30, 2019 2:39 pm

Not sure, I don't know the difference.

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Re: Voltage Regulator - Beetle

Post by retrovan » Tue Jul 30, 2019 3:35 pm

No More Landy wrote:
Tue Jul 30, 2019 2:00 pm
.................Can it be that the rain through the boot lid breathers wet the alternator ...........

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I think you had the lights on with the engine off or your battery not the best, but this is what happens when the battery is discharged, and the generator has to work hard to get the battery full and keep the lights on at the same time.

The charge light is directly connected to the battery well being, and if its not on voltage the light will glow dull, till the battery gets to voltage.

Herman
1952 Split Beetle 1835cc (Azure Blue)
1968 Fastback 2Lt.type4( Red)
1972 Low Light Bay Panel Van 2Lt type 4(White)
1975 Fleetline Panel Van 1914cc (Aqua Blue/White)
2019 MeFusco Beetle Truck

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Re: Voltage Regulator - Beetle

Post by No More Landy » Tue Jul 30, 2019 5:18 pm

retrovan wrote:
No More Landy wrote:
Tue Jul 30, 2019 2:00 pm
.................Can it be that the rain through the boot lid breathers wet the alternator ...........

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I think you had the lights on with the engine off or your battery not the best, but this is what happens when the battery is discharged, and the generator has to work hard to get the battery full and keep the lights on at the same time.

The charge light is directly connected to the battery well being, and if its not on voltage the light will glow dull, till the battery gets to voltage.

Herman
The battery is at full charge as I left it on the C-Tech while I was away and have been driving her all week without issue. Seems more moisture related, maybe a short in the headlamps but I think that would have blown a fuse first ?


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Re: Voltage Regulator - Beetle

Post by 73type2 » Wed Jul 31, 2019 10:42 am

AFAIK alternators can charge at idle speed but generators need a bit more revs, 2000 I think. Not directly related to your problem but it wouldn't hurt to replace your generator brushes. My '71 beetle's generator light was forever flickering at low revs, making me doubt whether it was operating properly. I replaced the points based voltage regulator with a solid state one and replaced the brushes. All is fine now. I found that the brushes are not that commonly available locally and was lucky to find a pair at Goeie Hoop Onderdele.

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