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
>