Converting HP-25 to NiMH batteries, possible?

[Maximilian Hohmann]

Hello!

(07-21-2022 01:40 AM)cubytus Wrote:  ... at some point display segments flash randomly...

That's usually the beginning of the end for any Woodstock calculator. When the battery is nearly fully charged, the unstabilised voltage from the charger keeps rising. The flickering ist proabably caused by dried out capacitors in the charger. A sure recipe for terminal damage...

Here ist the NiMH battery pack I use for most of my Woodstocks (I only have one such battery pack for all calculators). It has 2500mAh cells, so five times the capacity of the original 500mAh NiCd cells!
If you cut away the central beam across the pack and use the original spring, the batteries can be removed and put back into it without tools in a matter of seconds. Be sure to mark the polarity somewhere as reverse polarity will kill the calculator instantaneously!

Regards
Max