[NSRCA-discussion] NiMH Question

[Bob Richards]

The problem with some of the cyclers is that they do a fast charge, then discharge, then fast charge, etc. without ever "equalizing" the cells.  The problem is that one or more cells in the pack can become depressed more than others, and without a good equalization charge they will never be topped off fully since the cells that ARE fully charged will trip the peak detection when they come up.
   
  I suggest doing a C/10 charge for 16 hours, then cycle the pack and see what happens.
   
  Bob R.
  

Michael Cohen <precisionaero at comcast.net> wrote:
          I am cycling my batteries and getting ready for the flying season.  On my initial 5 cycle run at my NiMH batteries, both my 1650 mAh packs cycled very low.  One pack that I have not used since end of November only cycled up to 850 mAh and the other pack I have not used since end of September only cycled up to 1000 mAh.  My charger is set to 5 cycles, charge and discharge are set to .65 amps with a cutoff voltage at 1.1 Volts per cell.  I am now trying 1.00 amp charge/discharge with a 1.0 volt per cell cutoff and it is looking better, but I have some questions:
   
  1)  Did I damage the batteries by letting them self-discharge too low?  I know NiMH batteries have a higher self discharge rate than NiCD batteries, but I am not aware letting the NiMH batteries run down could cause damage.
   
  2)  Is this a normal behavior?  Maybe NiMH just need a little more juice at the beginning of the season.
   
  3)  Is the cold garage a factor?
   
  Thoughts?
   
  Mike Cohen
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