I've thought about this some more, and I did have this problem a few years
ago. The voltage is regulated by rectifiers - little round discs - inside
the alternator. These can be changed easily enough. I seem to remember the
whole thin came as a package, new rectifiers, brush holder and brushes. Got
the off of Ebay. That alternator is still running 5 years later.

John
On Jul 15, 2016 19:29, "Alistair Bell" <albell@shaw.ca> wrote:

I might be slow on the uptake here Dennis, but are you saying you measure
14.3 at alternator and 12.2 at battery?

And this is with a charged battery?

My first thought is that there is a big voltage drop between alternator and
battery.

If I measured this on my can I would be tracing along the positive wire to
the battery. I'd look at the connection at the starter.

But it's been a long day, I'm tired, I probably have mis interpreted your
results.

Cheers

Alistair

> On Jul 15, 2016, at 1:32 PM, Dennis Jowell <dennisjowell@gmail.com> wrote:
>
> Alistair,
> I did that this morning. Battery fully charged at 13.5 volts. At idle
Output from alternator is now at 14.3, at battery its 12.2 at positive
terminal.
>
> Dennis J
>
> Dennis Jowell
> Scotch Hollow Farm
> Newbury, Vermont
>
>
>> On Jul 15, 2016, at 3:22 PM, Alistair Bell <albell@shaw.ca> wrote:
>>
>> Measure alternator output at the battery. Charge up battery with charger
first then run engine and check voltage at positive battery terminal.
>>
>> Compare to the voltage at the alternator.
>>
>> Alistair
>>
>>> On Jul 15, 2016, at 10:47 AM, Dennis Jowell <dennisjowell@GMAIL.COM>
wrote:
>>>
>>> Just got back from a test ride. I checked the output of the alternator
at idle its 14.1 at the stud positive and grounded on engine frame and
stays there at high rpm. Yesterday I installed a new battery, changed it to
13.5 volts, drove 75 miles, new battery is now at 11.9-12.3. Engine is at
running temp. I have no idea where to go now. I thought the 5 years old
battery was DOD so,I changed it. All cables and wire are tight on battery
and alternator. All have dielectric on them.
>>> Help! Any thoughts where or what I should look at?
>>>
>>> Dennis Jowell
>>> Scotch Hollow Farm
>>> Newbury, Vermont
>>>
>>>
>>>> On Jul 14, 2016, at 12:40 PM, Stuart MacMillan <stuartmacm@gmail.com>
wrote:
>>>>
>>>> You need a high end tester/charger for this.  Parts stores and Sears
repair
>>>> shops will test it for free. Should have a minimum 75% output with
>>>> headlights lights and heater fan on. Alternatively, you can measure the
>>>> voltage at the alternator under this load.  Ideal output should be 14.2
>>>> volts, but 14 is typical. If 13.2 or less I consider it junk.
>>>>
>>>> I've replaced two recently that tested 25% with Bosch rebuilds from my
local
>>>> supplier (who could also switch the pulley for me), one of which
tested at
>>>> 50% when installed.  They replaced it. It's just the poor QC of
rebuilds, so
>>>> test your "new" alternator too.
>>>>
>>>> Stuart
>>>>
>>>> -----Original Message-----
>>>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
Behalf Of
>>>> Dennis Jowell
>>>> Sent: Thursday, July 14, 2016 9:11 AM
>>>> To: vanagon@GERRY.VANAGON.COM
>>>> Subject: Checking output of alternator.
>>>>
>>>> After driving my Westy to Middlebury, Vermont area decided to visit a
>>>> historical site in town. Westy started slow but it started back to the
farm.
>>>> Stopped at another state park and had some lunch. Westy now won't
start!!
>>>> Ugh! I used the aux battery to get it going and got home. Main battery
is
>>>> new. I suspect the alternator is NG. Once again trying to understand
the
>>>> Bentley test procedures on Pg. 27.18. What is " connect
alternator/regulator
>>>> tester" ?? All I have is my digital ohm meter. Is that what they are
saying
>>>> ?
>>>>
>>>> Dennis J
>>>>
>>>> Dennis Jowell
>>>> Scotch Hollow Farm
>>>> Newbury, Vermont
>>