Recently the wife had a dead battery with our 2002 Mercury Cougar. There=20
was no illuminated warning light. Checking the cars official service=20
manual, I find the following paragraph:

" If there is an open circuit in the regulator (built in) or generator=20
rotor circuits, the warning lamp will not illuminate"

Per the owner's manual, supposedly the charging system warning is=20
supposed to warn of low voltage, but wasn't on with engine running (jump=20
start) and 10 volt battery voltage.

In this case the fault was worn rotor slip rings in the generator=20
(that's what they call it, it's an alternator).

I'm thinking of adding a low voltage warning LED. Space is extremely=20
limited, and yet keep the installation neat looking and visible to the=20
driver, but there is an unused module between the traction control and=20
rear defroster switches that an LED could be mounted. Otherwise I would=20
prefer a 3 digit display of voltage.

To control the LED thinking of a 12F PIC, need one ADC to monitor the=20
battery (system) voltage, and one output to control the LED, including a=20
flashing mode. The Pic would preferably have a built oscillator, then=20
there would be voltage regulator, a couple of caps, and a few resistors.=20
I still am through the hole, and not into surface mount. I do have a=20
PICKIT 2 for programming, and usually use 18F13220 for my projects.=20
Haven't tried to look yet for the exact PIC yet, but will after I settle=20
on some of the issues here.

I would have preferred monitoring the amperage to/from the battery, but=20
that cable goes directly from the battery to the starter in an=20
inaccessible area, and then to the vehicle system. Adding a shunt in=20
that area is not feasible, though a hall effect or other device is=20
possible, then if the battery is discharging for more than a short=20
period,  set the warning.

Thanking ahead for any comments. :)
--=20
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