Re: Remote Car Battery Voltage Monitoring

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
news:440da2ed.298869468@xxxxxxxxxxxxxxxx
> 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.

That's a good point.  Still, voltage is better than no data at all in trying
to figure out whether the battery needs a charge.  There may be something
wrong with the the onboard electronics in the van because the battery has
lost its charge twice in the last two months.  I'm going to have to monitor
the standby current draw for a few days.

I bought a solar panel charger today that clips to the visor.  I think it's
unobstrusive enought to be workable for dad.  I am just not sure it will
deliver enough current to be useful.

> 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.

That's a great idea but it's more ambitious than I would like, especially
tapping into the starter circuit.  We'll see how the solar panel works out.
If that fails to solve the problem, I'll look at other potential solutions.

Thanks Dave! (110) <g>

--
Bobby G.


> "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!).
>