48v from 12v LiFePO4 in series

chilly2

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.

Questions...
  • 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.
 

coalfield

New Member
Looking at a similar setup to yours but 24V with an Epever 3322. Have the unit looks good but not made a jump on the batteries yet but will feedback as likely will get 2x 12v.

The manual is pretty good on 2P breaker recommendations but depends on the model of unit your looking at which relates to your max draw.

keep me posted how you get on and I will likewise. Where you based?
 

plaidcabin

Solar Enthusiast
Check with the manufacturer or seller before using 12v lithium batteries in series, the bms and internals might not be up to the task.

Better to assemble your own batteries with BMS rated for the voltage you want to operate at
 
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