Discharger circuit for NiXX cell

[Jony130]

I design this circuit for discharging NiMH battery.
Is this circuit can work properly ?
Did you see any errors 9n the diagram?

 

[MikeMl]

How many volts is the battery pack?

What sort of heatsink is the BUZ on?

 

[audioguru]

If the battery cell is a small AAA or AA size then I think the circuit will pulse on and off when the voltage gets near 0.9V because there is no hysteresis. When the cell is loaded then its voltage drops and when the load is removed then the voltage rises which turns on the discharging and it keeps repeating.

 

[Jony130]

The batteries are AA cell.
As for hysteresis I put T3 to add positive feedback. That not enough ?

 

[audioguru]

I think T3 is turned off all the time because the voltage divider of R7 and R8 reduce the base-emitter voltage too much. The BUZ10 Mosfet is guaranteed to have a very low resistance only when its gate is at 10V and to conduct at least 1mA when its gate is from 2.1V to 4.0V. The datasheet has "typical" curves but you don't know if your Mosfet is sensitive or not. So you won't know what voltage is at the output of the opamp. It might be 4V or it might be 8V.