Thanks for the reply. I am looking for massive failures like a failed=20
alternator, open circuit, etc. with the hopes of warning soon enough to=20
eliminate at road service call. The alternator is around 100 amp output,=20
and with the more usual ampmeter setup in series between the battery and=20
load/alternator, one can see in cruising down the highway, there should=20
be at least a minimal charge to the battery, but if a discharge current=20
is there at anything but idle RPM, even with big loads (headlights),=20
help is needed in a short period of time. I would be looking for changes=20
in amperages at least several amps magnitude. This warning didn't happen=20
in my wife's case, and I'm looking for a better way. My 1996 Ford Bronco=20
(think F150) has a system voltmeter on the panel, and that is fine. If=20
voltage isn't above 13 volts with anything above idle, there is an issue=20
also. I don't have a preference as to voltage or amp (unless someone=20
provides a good reason), both will do the job. In this case the voltage=20
is a whole lot easier to implement. On the Bronco, the amps would not be=20
difficult. All the cables are out in the wide open, a shunt would be=20
easy to find a mounting spot, and the instrument panel has a=20
conveniently located blank panel that removes easily. :)

On 7/23/2012 11:46 AM, Sean Breheny wrote:
> Hi Carl,
>
> When you say you would prefer to monitor the battery current, I'm not
> sure what that means. How will that tell you when the battery is low?
> I would be concerned about the ability to measure currents less than 1
> Amp accurately under the hood. I think I have seen currents of 10s of
> mA flowing between different parts of the car chassis due to
> thermocouple effects after things get hot. In other words, I've seen
> current flowing into the negative battery terminal from one lead and
> then OUT of the same battery terminal on another lead. Unless you can
> measure the total current of all of the leads going to one terminal of
> the battery, you may see spurious ground current readings because of
> small to moderate currents caused by differences in temperature in the
> car.
>
> Sean
>
--=20
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