Re: Battery level tester.

From: legg (legg_at_nospam.magma.ca)
Date: 09/27/04 

Date: Mon, 27 Sep 2004 01:09:28 GMT

On Sun, 26 Sep 2004 18:13:34 +0000 (UTC), "Colin Dawson"
<nospam@cjdawson.com> wrote:

>Didn't I? I take it that you read the original message.....
>
>"Is there something that I can do to counter balance this high current
>voltage drop?
>
>My thought on this is to place a kind of Ammeter into the circuit, that will
>adjust the value of VR1, in accordance to the amount of current drawn
>through the circuit. Changes in current would would effect this part of
>the circuit, and continuously trim the battery meter, so that the readout
>remains stable. (and hopefully correct)"
>

>From previous;
 
"Run two .... blah blah.............Kelvin connection.

"Alternately, one lighter-guage wire from the negative battery
terminal could be used to measure cable drop. Inverted (using
a single supply op amp) and resistively summed into your IC's
input pin (SIG), it could compensate for cable drops in the
measurement.

"In any event.......blah blah....... need."

The cable drop is the current sensing shunt betwen the battery and the
meter's ground reference at the load side. This sensing voltage is
easily inverted using a 358 or similar single supply op-amp, with or
without gain and resistively weighted to modify your meter's input, as
you request.

RL

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