I'm happy to announce that I just finished testing a new release of the firmware that supports 4-cell LiFePO4 batteries.  Although these batteries can't charge in environments as cold as lead acid batteries can (min of 0°C instead of -20°C), and are more expensive they have much longer life spans and can take many more charge/discharge cycles.  They're much lighter too!

The new firmware version 2.0 supports LiFePO4 batteries by detecting a jumper soldered between two previously unused test points on the top of the PCB.

Adding support was a little tricky as I am almost out of flash storage on the EFM8 micro-controller.  With the new LiFePO4 features below I now have something like a whopping 40-50 bytes of unused flash!

1. Float/Bulk initial charge state threshold set to 13.2V
2. Bulk Voltage set to 14.4V
3. Power On charge voltage set to 13.6V
4. Temperature Compensation disabled
5. Charge temperature range between 0°C and 50°C

The github repo has been updated and I also updated the mppt_dashboard app using the current version of Xojo, signing the OS X version and extending the current range on the graph from 0 - 2000 mA to 0 - 2500 mA.

Future orders from my tindie store will have the new firmware.   I'll think about how I could create a simple way for people to update their existing firmware if they want.  Please contact me if you are interested in this.