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 
>>