Adapting cell battery to HP 41

[Artur - Brasil]

(02-25-2019 03:55 PM)mfleming Wrote:  Nicely done! What did you use for the battery cover, and how did you connect with the battery contacts?

~Mark

Hi, Mark

I had one old hp41 rechargeable pack, whose batteries were dead, so, I cut it, leaving just small borders to insert in the original place.
I soldered two wires in the cell battery and soldered them in the recharger board. From it, another two wires to the step-up conversor; finally, other two wires soldered directly on the battery contacts of my HP41.
Very easy to do, realy! Also, you can use the calculator while charging. The step-up converter keeps exactly 6v on output.
2US$ solution!!!
Card reader supported like a brease!
Next works, my tape recorder and the printer ....