Thanks for all the good replies. I'll try to summarize my comments on=20
several messages:

On 7/22/2012 9:46 PM, Richard Prosser wrote:
> Do you really want to use a PIC?
I'm familiar with PIC's, have a bunch of the 18 pin and 40 pin=20
variations laying around  and the PICKIT 2 for programming. Very little=20
development time needed! Programming would mainly be cut and paste from=20
other applications I have in service. This is little more than "Blink=20
the LED". Thinking a 8 pin variant would do nicely. Then only need a=20
regulator, couple of caps and resistors. Also, I can program a delay of=20
say a few minutes before displaying the warning to eliminate the low=20
voltage during momentary heavy loads like starting.

     Neil wrote:

		Use a small PIC that has an ADC (IIRC the 12F675 and 12F1501 have 10-bit
		A/D's), an external reference voltage and a single bi-color LED.
		Green=3Dall good, red =3D below normal, flashing red =3D critically low, =
or
		perhaps over normal, etc.
	The 12F675 looks inviting.




>   I would have thought a TL431 driving
> a LED would be more than adequate.
Learning/development curve is time consuming, but otherwise looks good.=20
I did see the voltage monitor schematic.
> Re the mounting - can you re-use
> the hole for the existing warning light? (Too hard to get to I'd
> guess).
Yep, whole instrument panel comes out first, plus would like to leave=20
original vehicle intact.
> For the current- you could use the existing cable and measure the
> voltage drop across it.
That cable is maybe 00 gauge and less than 2' long in an inaccessible=20
location and carries the start current also.

Nily wrote:

Modify this one
http://tecnoface.com/alimentacion/10-indicador-de-nivel-de-carga-de-una-bat=
eria

This one has good possibilities. I probably have all the few pieces=20
needed in stock. Possibly modify it to use one bicolor LED. The mounting=20
area has behind, a 5/8" diameter tube that the other switch/LED units=20
slide into. Probably can mount 1 or more LED's on the end of a dowel,=20
and just cut (drill small holes for the LED to shine through. This dash=20
mounted module just snaps in place, just a little prying with small=20
screw driver and it's out.

This is a DIY kit
http://vortizefar.zobyhost.com/CIRCUITOS/indicador%20de%20bateria%20baja.pd=
f

A lot more pieces, but like the audible warning, but then would need slence=
r switch.



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