Re: Remote Car Battery Voltage Monitoring

[nobody@xxxxxxxxxxxx (Dave Houston)]

Voltage is not an adequate measure of the battery state. A battery needs to
be checked under load. Temperature also affects both the voltage and state
of charge.

I think a better approach would be a relay to open the starter circuit if
the battery charger is plugged in, perhaps with an indicator LED on the
dash.

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>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!).