48v from 12v LiFePO4 in series


New Member
My current setup is a 2k 60vdc array in 2S4P to a 2kw 45v-90v inverter. I'd like to add batteries and have been looking at buying four 12.8V LiFePO4 batteries from Amazon as they seem readily available, and putting them in series for 48v (51.2v), with a suitable charge controller.

I'm super anxious about adding batteries and want to be 100% sure everything is right so I avoid uncessary expense and / or house burning experiences.

Before - PV to combiner to inverter. *
After - PV to combiner to charge controller to busbars shared with battery and inverter. **

* - combiner has fuses, SPD.
** - Will add fuses and disconnect switches between all devices on busbar.

  • Has anyone else built a 48v LiFePO4 out of 12.8v's and did the BMS in each play nice?
  • If the charge voltage has to be ~57.6v, am I correct to rewire the array to 3S3P for 90v?
  • How does one calculate the correct fuse sizes and wire gauges between all devices connected to the bus bars?
  • I am looking at ePever charge controllers. Anyone like these? Other brand?
  • This would be in a garage. Provided they're secured, can the batteries be on open shelving or should they be inside a fireproof box?
If you have a setup like the above please feel free to share.