My Double Cab currently has a 65A alternator as the 90A blew a few diodes
on it and refused to charge a battery.  When running and no lights on I get
13.5V just like you.  With the parks on it goes to ~13 and low beams to
about 12.5, Hi beams to a little less than 12V and rallye lights bring it
down to a little less than 11V.

I would say that anything over 12V is considered good.  Our Cabriolet is
about 12V when the lights are on and there is no problem.  VW volt gauges
indicate anything over 11.5V is good.

At 14:12 06/12/98 -0500, jhlauterbach wrote:
>After seeing some apparently strange things happening to my gauges, etc., on
>my '84 DL, I have temporarily connected a voltmeter to the connector that
>would normally go to the radio.  I have noticed the following (all readings
>approximate).
>
>voltage before starting - 12.5
>voltage after starting - 11.7 (BATT and OXY lights on)
>voltage after increasing engine rpm's slightly - 13.5
>voltage will operating at highway speeds with headlights off - 13.5 to 13.7
>voltage drop after turning headlights on with engine running at any speed -
>0.7 to 0.9 volts
>
>Are above readings normal?  I would have expected that voltage regulator
>would have reacted to headlights being turned on and brought voltage back to
>13.5.  Do I need a new voltage regulator?  If so, how much of a job is it?
>
>John Lauterbach
>
>

-- David Marshall                                    --
-- 78 1.8L VW Rabbit, 80 2.0L VW Caddy, 87 Audi 5KSQ --
-- 85 VW Cabriolet, 88 2.0L VW Syncro 16" Double Cab --
-- Volkswagen Homepage   http://www.volkswagen.org   --
-- Volkswagen/Audi Parts http://parts.volkswagen.org --
-- mailto:david@volkswagen.org - Quesnel, BC, Canada --