> I'd
> probably use a PWM output of a PIC driving a FET and a fixed resistor as
> the load. Adjust the duty cycle to set the average discharge current.

Good enough for some tasks such as gross ask-no-questions discharge,
but dangerous or misleading for others,

If building a universal chemistry unit (as i think was mentioned) then
discharging at above 2C may be unsafe or damaging for some Lithium
cells.

Also if you can accomodate a ide range of mAh capacities the peak PWM
load has to be the max capacity cell x the max desired C dischare
rate.
eg if you want to accomodate 4000 mAh cells at up to 2C discharge you
need 8A discharge.
If you are discharging AAA cells they may object or work funny if you
discharge them at 8A/9800 mAh =3D 10C. Or may not.

If doing capacity testing then say 4C at 25% duty cycle may produce a
different result to 1c at 100%.
The difference should be small but may be significant.



           Russell
--=20
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