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'(OT) PIC based amp-hour meter'
1998\03\13@122641 by

Anyone have any tips on making an amp-hour meter for a solar power setup?

I have about 20 amps of charging current going into a bank of 440Ah, 12V
batteries feeding a 500W inverter.

I have a 200A 50mV shunt that will be used inline with the battery.

I'm going to take the voltage from the shunt to feed a voltage to frequency
IC, and then count the pulses.  There will be two V to F circuits, one for
charge, the other for discharge.  The pulses will feed into a '54 driving a
16x2 line LCD display.

Anyone see anything wrong with the above plan?
Dave
At 08:25 AM 3/13/98 -0800, you wrote:
>Anyone have any tips on making an amp-hour meter for a solar power setup?

Try the Whatt Meter model 101 from http://www.astroflight.com

Sounds like it does what you want, and only costs about \$60.00.

Andy

==================================================================
Andy Kunz - Montana Design
Go fast, turn right, and keep the wet side down!
==================================================================

>  David Schmidt <dschmidtSILCOM.COM>
> Anyone have any tips on making an amp-hour meter for a solar power setup?
>
> I have about 20 amps of charging current going into a bank of 440Ah, 12V
> batteries feeding a 500W inverter.
>
> I have a 200A 50mV shunt that will be used inline with the battery.
>
> I'm going to take the voltage from the shunt to feed a voltage to
frequency
> IC, and then count the pulses.  There will be two V to F circuits, one
for
> charge, the other for discharge.  The pulses will feed into a '54 driving
a
> 16x2 line LCD display.
>
> Anyone see anything wrong with the above plan?
> Dave

Why do you want to use V-F convertor ? Use PIC with ADC! I suppose that 8
bit its enough (to use C71/C74), or use PIC14000 with it "up_to_16_bit".
Of course, you can use OP Amp to amplify your 50 mV to 5V ADC input.
I reccomend Analog Device's OP291 - Micropower, Single Supply,
Rail-to-Rail Input & Output.

Alex Torres, Kharkov, Ukraine (exUSSR)
altorchat.ru
2:461/28@FidoNet
www.geocities.com/SiliconValley/Lab/6311

>  David Schmidt <dschmidtSILCOM.COM>
> Anyone have any tips on making an amp-hour meter for a solar power setup?
>
> I have about 20 amps of charging current going into a bank of 440Ah, 12V
> batteries feeding a 500W inverter.
>
> I have a 200A 50mV shunt that will be used inline with the battery.
>
> I'm going to take the voltage from the shunt to feed a voltage to
frequency
> IC, and then count the pulses.  There will be two V to F circuits, one
for
> charge, the other for discharge.  The pulses will feed into a '54 driving
a
> 16x2 line LCD display.
>
> Anyone see anything wrong with the above plan?
> Dave

Take the MAX471/472 precision high-side current sensor together with a
PIC with an integrated A/D. That should give you excellent results !

good luck,   R. Monsees

--
BAMBERG & MONSEES GbR
Systeme f|r Wissenschaft und Technik
Am Postmoor 36 * D-28719 Bremen
Fon +49-421-646775 * Fax +49-421-646785

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