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A project log for LiFePO4wered/Pi+

Next Gen LiFePO4 battery / UPS / power manager for Raspberry Pi, ideal for headless and IoT use

Patrick Van Oosterwijck 05/19/2017 at 23:350 Comments

After hacking on firmware for the past two weeks, I'm happy to report that the prototypes are working!

Here are my two protos: running a Pi 3 and a Pi Zero W:

The prototype in the back uses a 18650 LiFePO4 battery and stackable header, the one in the front uses a 14500 (AA) LiFePO4 battery and normal header. To remove the excess PCB used for the bigger battery from the unit with the smaller battery, I had added perforations to the PCB, but I was worried that the copper foil might peel when breaking it off. I decided to see what would happen with and without scoring with a knife, so I scored only part of the perforated area. Here's the result:

The section of PCB broke off very clean, and I honestly cannot see any difference between the part that I had scored and the part that I hadn't. Very good news! I'll have to see what happens when breaking off the bigger section when I'm ready to build a prototype with external battery.

On the firmware side, I worked on the following:

Once functional, I could do some preliminary testing, and things look promising:

Next I'll need to do more detailed high-power testing to see where the limits are. I still need to add registers to set the boot and shutdown timeouts and implement RTC functionality.