Adapting cell battery to HP 41

[Artur - Brasil]

(02-27-2019 03:48 AM)Craig Bladow Wrote:  A very creative solution! I believe the card reader is the largest typical load a 41c will see.

I agree with you.
About the cell phone battery, there are plenty of them out in market. Anyone that feets inside the HP-41 can be used.
The idea is: as much mAh you can get, go for it!

(02-27-2019 03:48 AM)Craig Bladow Wrote:  Now if there were a 3d printed battery pack to hold these components and spring loaded battery contacts.....

About the idea of a battery pack printed in 3d process, it would be the best.
In my solution, the board of charger was inserted in the side hole for AC adapter.
I had to make a small recess on HP to fit the board. I also had to cut in the board too.
I removed almost all the side of battery pack allowing to keep the boards in 41.
I also covered the space of battery pack in HP41 with tape to prevent lackage get inside it. This would be solved using a new sealed case, the one printed by 3d proccess.