[T3] Generator woes.

Jim Adney jadney at vwtype3.org
Tue Sep 30 18:58:40 PDT 2014


On 30 Sep 2014 at 14:34, Eric Nielsen wrote:

> Is there a way to test the voltage regulator?  I have a solid state and a
> standard one.

There's no simple test for the VRs. The only practical way is a 
process of elimination.

> Just got my 73 auto square back up and running and now the Gen light
> is shing bright as ever.  If I rev the motor it only dims at 3k rpm. 
> 
> I checked the voltage at  d+, and at speed I am only getting 3 or 4
> volts,  2v at idle. 
> 
> I also tried another generator, got it installed with the solid state
> vr and tested and was getting the 12-14v .  Then about minutes later
> my Gen light is back on and only getting the 3-4v output.

You're right, those voltages are too low.

There are 3 parts to our charging systems: generator, VR, and wiring. 
You can check the generator, inspect the wiring, and the VR is only 
suspect if everything else checks out. I'm sending you my generator 
FAQ that will walk you thru checkout of the system.

What are the chances that the generators haven't been mounted 
properly, with the air cooling hole pointing straight down (and the 
stamped dash on the generator lined up with the dot in the holddown 
strap?) If there's no air cooling, the generator will overheat and 
die. 

> I thought maybe the generator needed to be polarized. So I did that
> and still its not good. 

Polarization is something that might be necessary only if the 
generator field coils have been disassembled or if the engine was run 
with the battery installed backwards. I never recommend repolarizing 
because there's a very significant chance of doing it wrong and 
causing real damage, or reverse polarization. It doesn't sound like 
you did any harm, but I like to discourage people from trying to 
polarize their generators.

Here's the straight dope: Every time your engine starts and the 
charging system starts working, your generator gets repolarized. A 
generator that was polarized yesterday, a year ago, a decade ago, or 
a century ago is still polarized today, unless (possibly) it has been 
disassembled or run with a reversl polarity battery.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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