A question about alternative power supply for hp41 series

[Dieter]

I'm a bit late to the party, but let me add my 2 cents anyway. ;-)

(02-17-2016 11:39 AM)isanchez Wrote:  Despite the golden contacts are present or not, in the keyboard card you can still see the two connection points.
My question is simple: does it work? Are they functional?
If yes, would it be possible to charge four N-size rechargable batteries?, or is it just to power on the calculator?

As far as I know the HP41s do not contain any charging circuitry. That's why the 82120A pack had its own PCB, and later external chargers for N-cells were offered.

Alternative battery solutions for the HP41 have been discussed here several times – obviously this is a topic that shows up every few years. Maybe the last threads (in the old forum) may give some additional insights, e.g. on possible battery options. Cf. this thread which also links to that one.

BTW, has anyone ever thought of using a 2CR5 Lithium battery? These were quite common in photo cameras, they are as small as 17x34x45 mm and offer 6 V nominal voltage with 1200...1500 mAh capacity. Which is almost twice as much as an N-size Alkaline cell. Or 20x that of the original 82120A pack. ;-)

For my 41s I sometimes use a custom-made connector that fits the battery compartment. A short cable ends in a button-type connector (the one that is also used on 9 V batteries) which fits on various battery holders, e.g. for 4x AA. Or even 4x D if you think that up to 20 000 mAh are required. ;-)

Dieter