40aH LiFePo4 Battery Box (w/Solar)

Parts List

2x ECI Power 12V 20Ah LiFePO4 (parallel)
Victron Energy SmartSolar MPPT 100v/15a Solar Charge Controller
2x USB A (2.4a ea)
1x USB A QC 3.0
1x USB C PD (power delivery for charging laptops)
1x 12v Accy Port (Cig Lighter)
2x Andersons Powerpole (Bi-Directional)
1x Andersons Powerpole (direct to batt)
1x Andersons Powerpole (direct to MPPT)
Inline Shunt Power meter (voltage & current)

Summary

The case got a bit scuffed during the build, thanks to my Dremel giving out mid-project. Each component is individually fused and switched, with Anderson Powerpole inputs for external DC charging and a solar panel hookup (up to 100V/15A). Both batteries come with built-in BMS, so charging is simple: supply 14.6V for absorption charging and 12.8V (or 13.8V) for float.

The maximum charge rate (via DC or solar) is 10A, though 5A is a safer and easier choice. Using a 14.6V 5A smart charger, a full recharge from 0% to 100% takes about 6-7 hours. The load output on the Victron unit isn’t used, as it maxes out at 20A, and I wanted a 40A maximum load.

This setup pairs well with my ROCKPALS SP003 100W Portable Solar Panel. I haven’t been able to test the solar charging yet since we’ve had limited sun here in the SF Bay Area. If you’re interested in building something similar, check out my parts list here. You can adjust the build to fit your box size and battery capacity!