Johnny B Good wrote:


Quad list it as a 4V battery - quite how they achieve that is another
question altogether!


** Quad have " 4.8V NiCd " printed on the schem next to it.



It might be the charger's nominal upper voltage limit for a 3 cell NiCd
(blue) or 3 cell NiMH (green) battery. Constant current charging of
either type results in a 'resting voltage' immediately after going off
charge in the region of 1.4 volts per cell, usually dropping to 1.36
volts after a day or two. The 1.2 volts rating for these cells is the
minimum voltage just prior to becoming exhausted of useful charge.


** The rest voltage of a NiCd cell is 1.25V - under a moderate load it drops to 1.2v and is exhausted at 1.1V.

When trickle charged in memory back up use, there is just enough charge to compensate for internal self discharge - normally about C/50. So for a nominal 150mAh cell, that equates to a 3mA trickle charge.

A good condition, 4 cell pack ought to measure between 4.8 and 5V.

Same goes for NiMh cells.



..... Phil