Negative Delta V vs Zero Delta V
The default -dV value of my charger was 3 mV. I had to set it to 0 mV. Why? Because it was cooking my batteries!
I had several problems with the default value:
- at smaller rates (300 mA and less) the pattern never formed and the charging did not want to terminate
- at higher rates it worked reliably only for new cells. The old cells ended up overheating while waiting for the 3mV drop. It was the thermal protection terminating the charge process, not the -dV algorithm
Since I switched to 0dV the charger did not miss a single termination and the old cells fill up before overheating.
Recommendation: For charging NiMH cells use 0dV when possible or the smallest -dV value possible.