Hybrid battery balancing

Obviously something happened to this darkened bare cell and it was not a polarity reversal.

 

FWIW, even the Hybrid Automotive Prolong Reconditioning units were raised from 17v to 84v for the lowest discharge on the newer units they sell.. I suspect they had too many problems with cells failing for exactly the reason you're discussing here.

 

If you discharge your pack with a high current, down to 17 volts, then you have a real chance of killing your battery. I reviewed a lot of information on nimh batteries and low current charge/discharge is the correct way to restore nimh batteries.
One article on reconditioning nimh batteries used in aviation instructed that they be discharged and left discharged for 24 hours. I haven't tried this. I won’t try this on a good battery, but it’s unlikely to help in any way on a bad one. But, I left a few battery packs discharged for ~10 hours and I don’t know if there is a difference in this, i haven't checked. I recently tried to find this article to read again but i could not find it.
I only discharge battery packs this low that are 65% or lower of health.