I'm not really looking for a way to perform the discharge.  I already have
designed (and built and started testing) a FET based system that has a 24-bit
digital feedback loop running at about 4kHz.  This works excellent for
controlling current well into the nano-amp range.  Right now the project is on
a combination of solderless breadboard and proto boards.  I am drawing up a
PCB and want to select the best possible components because the tester needs
to be very accurate.

So, if anybody has any info on the pros and cons of different types of
resistors, that is really what I need to know.

Sorry if my original post wasn't very clear.  Thanks for all the help :)

Eric


On Wed, 7 Apr 2004 13:08:03 -0500
David VanHorn <dvanhorn@CEDAR.NET> wrote:

> At 02:19 AM 4/7/2004 -0500, Eric Christensen wrote:
>
> >I am building a battery testing device that will run long-term (1-2 year)
> >tests on different types of batteries.  This device has a few resistors in
> >the battery discharge part of the circuit that I would like to be as
> >'ideal' as possible.  The resistors will see currents from 5 amps (the low
> >ohm ones) to a single uA (the high ohm ones).
> >
> >Does anybody have any info about the various types of resistors.  I need to
> >know things such as the capacitance, inductance, etc... as well as the
> >stability over time.
>
> Why not use one or more constant current sinks?
> They can be made to be programmable, or just two-terminal devices.
>
> This is what I used for my battery project at:
> http://www.dvanhorn.org/NIMH/Index.php
>
> The graphs are about halfway down, links in the text.
>
> A CCS dosen't exactly act like a resistor, but it's easier to figure
> amp-hours and Joules, if you aren't constantly measuring.
>
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