89 200tq strange behavior with low battery.

[Ti Kan]

Kurt Deschler writes:
> I had two problems with my 89 200tq after it sat for a couple weeks. The 
> voltmeter was reading around 11V. First, the starter was not getting 
> voltage to the solenoid. Does anyone know if there is a relay in that 
> circuit? Second, the door lock vacuum pump would stay running when the 
> door locks went down maying it impossible to unlock for around 20 sec. 
> After charging the battery some, both problems seemed to go away. Has 
> anyone seen these problems? I am especially worried about not being able 
> to start if the battery is low.

The solenoid *is* the "relay" to activate the starter.  If there is
not enough charge in the battery then it's not surprising that
the car won't start.  Also, if the battery is weak, the door lock
pump probably also runs slowly, causing the pressure (or vacuum)
in the lines to not reach high enough a level, hence the pump keeps
running.

The battery's lifespan will be shortened when it's subjected to a
discharge like that, so the next time you are going to leave it
undriven for an extended amount of time, I suggest hooking up
a battery charger.  Not just any battery charger... there is a
special type that stops charging when the battery voltage reaches
a certain threshold, and resumes charging when it drops.  The one
I have is called "Battery Tender Plus" from Deltran, which I bought
from Pep Boys.  Overcharging with a less-smart charger would cause
the battery to fail too.

VW/Audi also makes a solar-powered battery charger (basically a
small solar panel with suction cups you could fix to the inside
of a window, and plug into your cigarette lighter).  This is used
by the factory to keep the new cars' battery charged while they're
being shipped.  The factory part number for this nifty device is
1CO 915 687.  Very inexpensive and there are lots of these being
sold on ebay (search "vw solar panel").

-Ti
-- 
Ti Kan
http://www.amb.org/ti
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