Re: Remote Car Battery Voltage Monitoring

["BruceR" <br@xxxxxxxxxxxxxxxx>]

I have a car at a second home that sits for months without use and a
marine battery that sits in a small sailboat to power a bilge pump and
lights. For the boat, I found a flexible, waterproof solar panel at West
Marine that keeps the battery fully charged. In 4 years I've never had
to charge it with anything else. For the car, I use a Battery Tender Jr.
to keep the battery "ready-to-start" and it works well. Rather than
monitoring the battery's condition remotely, in both cases I just use
the chargers and never have to worry about it. If the car has a lighter
socket, power outlet that's always on you can just plug it in that way.
 http://tinyurl.com/k9w56 shows the Battery Tender Jr. and you can buy
it for under $30 at places like Pep Boys.


> 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!).