whoa there Tom!

  The bosch alternator in the vanagon never did put out 14.5 V.

I bet if you look closely at the voltage reg you will see 14.1 V
written on it. And even when new, seemed to struggle to get to 14.1

Alfred,  make sure all your connections from alternator to battery
are squeaky clean - shiny!- and tight.

PS disconnect battery before working on this problem - red wire at
alternator is "hot" all the time.

If you feel up to it, remove the voltage reg from alternator and
check brush length. Specs and procedure in Bentley. (pmail me if you
dont have procedure).

Then when all is cleaned up and back together, try measuring voltage
again, both at battery and at alternator. If all is well you should
not see more than a 0.1  V diff. between the 2 measurements.

The previous low voltage condition was probably chronically
undercharging your battery, so if you can, put the battery on a charger.

alistair

On 17-Jul-10, at 11:18 PM, Tom Hargrave wrote:

Alfred,

13.8 volts is considered minimum and the fact that you see 13.8 at the
alternator and 13 at the battery tells you have a very, very low
battery or
the alternator is in trouble.

I'd suggest you do a good job of cleaning & then re-attaching your
battery
terminals, charge the battery and test again.

Most charging systems will float up to 14.5+ or so, at least the Bosch
alternators on all the Mercedes I've owned would. I don't own a
Vanagon yet
but a charging system is a charging system. If you don't reach at
least 14.5
volts with a fully charged battery then I suggest you have a alternator
issue.

Tom
www.towercooler.com