HP-41 Batteries

[Dieter]

(03-01-2015 04:06 AM)TASP Wrote:  Do the NiMH batteries have the same 'knee' effect on the voltage the NiCds had ?

I am not sure what you mean here. If you refer to a more or less sudden voltage drop before the batteries are exhausted: yes, that's essentially the same with NiNHs.

(03-01-2015 04:06 AM)TASP Wrote:  It can mess up the card reader if the 'knee' occurs during an operation, for those who recall such minutiae.

You may want to take a look at the manual. The 82104A card reader has several means to handle low batteries. If the voltage drops while a card is read, the motor switches to intermittent operation. It is turned off and on for fractions of a second until the card has passed through the reader. A low battery message appears in the display (not just the usual BAT annunciator). If the batteries are completely exhausted and the card gets stuck in the reader, simply disconnect it, install a fresh set of batteries and re-attach the reader. The card will then complete its travel.

BTW, what kind of dedicated N-Charger are you planning to use? What is its charging current and what kind of charge control does it use?

Dieter