Finally I got my HP-67!

[Craig Bladow]

Here is an article on building classic battery packs I found a link to in the articles section of the forum: http://homepage.divms.uiowa.edu/~jones/hp/battery/

My thought is to build an adapter that would fit a particular camera battery that can be easily removed and charged externally. For example the third party batteries sold as substitutes for the Olympus Li-90/92b batteries. On Amazon there are several options for less than $20 that include two batteries.

What is needed then are spring loaded contacts, a case (3d printed most likely), and thin conductive material to connect to the calculator's contacts. This material needs to be compatible with the metal (what is it?) used for the contacts so it does not cause corrosion.