Remote Car Battery Voltage Monitoring

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

Anyone have ideas or sources for remotely monitoring an infrequently used
car's 12V battery to make sure it didn't go dead from simple attrition?

Ideally, I want some sort of contact closure when voltage drops below a
certain point.  I want to sent that information wirelessly to a base unit
inside the house that would flash, beep, and then call my cellphone and say
"Dad's wheelchair van needs recharging."

What I would like to do is hijack a wireless thermometer - the thermistor
probe should be able to read voltage with a few modifications to the probe
end.  The thermometer base station has an  "alarm on temperature" feature
that could, with a little recalibration, serve to monitor dropping voltage
and to beep when it dropped below a threshold I would set.   With any luck,
I could get it to read 100 degrees when the battery was fully charged and 0
degrees when depleted.  Not sure there would be linearity along the scale,
though!  <g>

Another thought would be some sort of docking cradle on the front bumper
that allowed feeding a charging current to the car without the need for
connecting charging cables or a charger that can be dragged down the street
for several blocks until the car manages to run over it (the reason why I
just don't leave the sucker plugged in all the time for him!).

--
Bobby G.