> David wrote Oct 30:
> In addition, others on the list have pointed out that the VW
> alternators/regulators don't cope well with the additional voltage drop
> that the diode-type isolators (the ones with fins) provide, so with those
> isolators, you may end up not having either battery completely charged.

About the voltage drop of isolators:
With the engine running, the vdo gauge I installed on my dash shows a
steady 13.8 volts on the main battery. That is plenty for me. In addition,
the little battery indicator light by the sink goes to green with the
engine running,
even if the auxillary battery is near empty. I never had a problem with
batteries not fully charging.
I used this brand of isolator for 12 years, on my ex-81 and my current '90
vanagons. Never had a problem with voltage drop that I noticed.
The isolator never damaged the alternator, or for that matter, never
damaged anything.
I've always used a vdo voltage gauge on the dash, and so I am always
monitoring the output of the alternator.
I called Sure Power to ask them about the voltage drop of their isolators.
They said it was negligible. Sure Power has a technician available to
answer questions. Their phone number again: (503) 692-5360.
I am in no way affiliated with this company.
Harald
'90 westy