NiMh battery equaliser

[drewc]

I have a circuit that will discharge NiMh batteries to around 0.6v because of the diode. This will discharge at around 2amps which is ok but I need a better design that will allow me to vary the cutoff voltage from 1volt to 0.8volt. Can anyone offer a better design that can be used with a pack of 6 batteries (7.2) and equalise them individually. Thanks in advance

Qty Part No. Description
6 1N5404 3A Rectifier Diode
6 R47 5W resistor .47 Ohm Resistor

Circuit Description
What happens is a resistor and diode have been placed across each cell. The cell will discharge until about 0.6v at which point the diode will stop the discharge process. This method nullfiies the problem of cell reversal associated with discharging the entire pack at once (cells in series).

 

[chemelec]

Discharging to .6 Volts is far TOO Low, So really is your .8 to 1 volt.

Discharge should be to about 1.1 Volts and it should occur at a rate of close to "1C" and at a Constant Current.

Using an LM317 or an LM350 as a Constant Current discharge and in conjunction with a Comparator, you can create a Much Better Circuit for doing this.

 

[drewc]

I am new to electronics and can understand that the LM 317 will give 1.5A and the LM 350 will give 3A. How do I piece together the comparator and the regulator together and do I need 6 circuits for each individual cell?? Thanks

 

[ante]

I use two Schottkys and one resistor on each cell, gives perfect cutoff voltage!
Constant current is not that important when discharging as when charging the cells. 8)