[Rollei] Discharging and Charging NiCad 6008i Batteries

[Mark Malkin <mm15 >]

I have found that the best way to discharge - and charge - the 6008 
batteries is with a Maha universal charger or similar electronically 
controlled charger.  This charger (I have the MH C777) cycles the batteries 
through a full but controlled discharge and charges with pulsed high 
current controlled by a microprocessor.  The charger senses the actual 
battery voltage/current/time curve to determine endpoint (dv/dt) a method 
that works for a wide range of battery types and voltages. It seems to give 
me significantly more battery life than my Rollei charger and It can 
connect to the Rollei batteries with only a small amount of fussing.

  Batteries can best be discharged when there is access to each individual 
cell which  is then separately discharged through a diode and resistor or 
lamp.  This avoids the bad effects of reverse biasing the first cells to 
quit in the battery pack. Like most multi-cell batteries there is no access 
to individual cells in the 6000 batteries so safe discharge requires 
monitoring the overall pack voltage and looking for the change that occurs 
when the first cell drops off.   . The electronic discharge in the Maha 
charger is terminated when the electronics sense that the weakest cell has 
dropped to (near) zero; this can be sensed by the dv/dt at the charger 
terminals due to the characteristics of the batteries.

Holding the 6000 battery with the clip down and looking at the row of 
contacts with the fuse just above them the first four of the six terminals 
on the 6000 series battery are:

fused positive  (the camera uses this )
negative
negative
un-fused positive   (use for the charger plus side connection)
terminals 5 and 6 are for a sensor - possibly to sense the temperature rise 
that occurs when charging is complete - one way many less sophisticated 
chargers work.

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End of Rollei Users list digest V10 #163
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