It's alive, the franken41

[Nate Martin]

The HP-41CV is still alive and well, passing all diagnostic tests. I will try to upload some pics soon.

My real hope was for the power pack. a LiPo battery using a charge/boost adapter (SparkFun Power Cell, PRT-11231) that fit well within a 3D printed housing. The power supply works well for 3-4 days with a 400mAh-500mAh battery but the no-load current on the boost circuit is just too high and quickly depletes the battery to the low voltage protection point. I have been comparing load with larger LiPO batteries, NiMH, and NiCad batteries and it is the boost circuit that is depleting too quickly.

Maybe I can use a solar cell mounted on the battery housing, I can then just flip over the calculator when not in use to keep the batteries charged.

So far the best power solutions I am finding for the 41C's are using the standard battery housing (OEM or 3D printed) with either NiNM N-cells (with a 3D printed AA:N adapter for recharging the cells) or standard N-cell alkali batteries, and rebuilt NiCad pack using 1/3AAA cells.