Horsefly
Solar Wizard
Just finished my second LiFePO4 battery build. Actually this one is my fourth one, but two the previous two were not for me and so I didn't have as much latitude for the design.
My previous build (discussed here) is for our mountain cabin, and had lots of emphasis on insulation, heating elements and controls for them, and likely unattended operation for months at a time. That was was a 8S 230Ah battery.
This new one is in part just to have it, but also may be hooked in parallel to the cabin battery for heavy usage periods. It also is 8S, but this one is 160Ah cells that I bought from Jenny Wu @ Docan.
Here's a view of the box from the top on the black / negative side. The box made of 3/4" plywood is 20" (51cm) long and 8.5" (22cm) wide, not counting all the stuff mounted on the outside. All-in it weighs 66 lbs (30kg). I can carry it, but I would rather not make a habit of it.
I used the JK BMS this time (B2A8S20P). Thanks to other folks on this forum (especially @upnorthandpersonal) the transition after using JBD on the previous 3 builds was easy.
Here's the red / positive side of the box, including the fuse and disconnect switch, with a 10 ohm, 25 watt pre-charge resistor on the switch:
Someone else here had suggested using the toolbox liner foam (sorry I don't remember who) so I used that between the cells and on the ends of the pack. On one end I also capped the stack off with a piece of sheet metal, and used four 1/4" x 1" bolts to put just enough compression to keep the cells from shifting around in the box. The bolts are actually not quite finger tight. I'm not a fan of "compression fixtures" so I really just want to restrict movement.
I also topped the box with a 1/8" piece of Lexan to protect the cells from me dropping my wrench across cell terminals.
I put a 175A Anderson connector on to finish it off. I then have the corresponding 175A connectors on my cabin battery box, my bench power supply (for charging), and the small 24V inverter I have here at home.
All in all I think it turned out well.
My previous build (discussed here) is for our mountain cabin, and had lots of emphasis on insulation, heating elements and controls for them, and likely unattended operation for months at a time. That was was a 8S 230Ah battery.
This new one is in part just to have it, but also may be hooked in parallel to the cabin battery for heavy usage periods. It also is 8S, but this one is 160Ah cells that I bought from Jenny Wu @ Docan.
Here's a view of the box from the top on the black / negative side. The box made of 3/4" plywood is 20" (51cm) long and 8.5" (22cm) wide, not counting all the stuff mounted on the outside. All-in it weighs 66 lbs (30kg). I can carry it, but I would rather not make a habit of it.
I used the JK BMS this time (B2A8S20P). Thanks to other folks on this forum (especially @upnorthandpersonal) the transition after using JBD on the previous 3 builds was easy.
Here's the red / positive side of the box, including the fuse and disconnect switch, with a 10 ohm, 25 watt pre-charge resistor on the switch:
Someone else here had suggested using the toolbox liner foam (sorry I don't remember who) so I used that between the cells and on the ends of the pack. On one end I also capped the stack off with a piece of sheet metal, and used four 1/4" x 1" bolts to put just enough compression to keep the cells from shifting around in the box. The bolts are actually not quite finger tight. I'm not a fan of "compression fixtures" so I really just want to restrict movement.
I also topped the box with a 1/8" piece of Lexan to protect the cells from me dropping my wrench across cell terminals.
I put a 175A Anderson connector on to finish it off. I then have the corresponding 175A connectors on my cabin battery box, my bench power supply (for charging), and the small 24V inverter I have here at home.
All in all I think it turned out well.