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NiMh battery charger with BQ2002E doesn't work

Other Parts Discussed in Thread: BQ2002E

Hello.

First, i apologize for my bad english, but i'm an italian guy.

 

I built a ni-mh charge battery with BQ2002E. I used the circuit similar to DV2002L2/TL2 (picture below). I used two different voltages: one, 12VDC, is DC input, and other, 5VDC, is VCC.

  

 

This is the problem. When i turn on the system, the voltage across the two ni-mh AA battery cell increase from 2.65V to 4.4V. So, BQ2002E detect the voltage above 2V per cell, and this pull down the emitter of Q1. In this case charge phase stopped (LED turn off). I measure the voltage of the emitter of Q1 and this voltage changes from zero to other values (0.4V, 0.6V, 1V, 0.4V, ...) because i think BQ2002E try to restart the charging cycle unsuccessful.

 

Can you help me?

What's the matter?
Thank you!