Sdr thanks for the information.

Questions number 1 and number 2 are somewhat critical for determining if the unit can be easily calibrated. If it was 'for sure' a constant current discharge circuit over the entire discharge session then this is very helpful. And then if the constant current discharge can be adjusted by adjusting a potentiometer (a variable resistor) or by replacing fixed resistors that would also be helpful. Sounds like too many unknowns atthis point. At least your friend informed you about the discrepancy.