I've completed the last revision the battery before I head to Kanas next week (in theory) to pick up the new RV and install this (at their facility with their assistance WRT any welding or physical work beyond my capabilities).
The previous revision had a few spots that were +40F under 120 amps of load, so I thought about it and figured out a better way to do the bus bars at the ends of the strings. I previously had 3/4" x 1/8" everywhere ... because I can't fit 1" wide bar through the hall effect current sensor. But for some reason (I've been at this for too long) it didn't occur to me to use 3/4" only for the current sensor, and 1" everywhere else. And that I could still terminate everything with 1" if I build a "bridge" with 2 3/4" pieces sandwiching the 1" pieces on either end:
I just ran 9000 watts through the system and observed a +15F maximum temperature rise. Woot!
I also decided to create a dedicated standoff system for the BMS and Breaker boards which would move with the cells as they expand and contract. Having them screwed down to the black threaded rod meant that there were considerable stresses on these bus bars and I saw the contactor ripping away from the plywood.
So this version has heat shrink on the bus bars at the ends of the cells (I don't have enough to do the cell bus bars and man I'm tired of working on this thing lol). I also got all the wires in split loom and secured with strain reliefs.
BMS board with contactor, SSR, and Ethernet for CANBUS:
Other side of that board:
Looking down the cells from that board:
Breaker board:
Other side of breaker board:
Entire set:
Back of the set (this is 1 gauge wire temporarily, will be 3/0 in the RV):
That wire, BTW, supported the 9000 watt load with a +25F temp increase.
The previous revision had a few spots that were +40F under 120 amps of load, so I thought about it and figured out a better way to do the bus bars at the ends of the strings. I previously had 3/4" x 1/8" everywhere ... because I can't fit 1" wide bar through the hall effect current sensor. But for some reason (I've been at this for too long) it didn't occur to me to use 3/4" only for the current sensor, and 1" everywhere else. And that I could still terminate everything with 1" if I build a "bridge" with 2 3/4" pieces sandwiching the 1" pieces on either end:
I just ran 9000 watts through the system and observed a +15F maximum temperature rise. Woot!
I also decided to create a dedicated standoff system for the BMS and Breaker boards which would move with the cells as they expand and contract. Having them screwed down to the black threaded rod meant that there were considerable stresses on these bus bars and I saw the contactor ripping away from the plywood.
So this version has heat shrink on the bus bars at the ends of the cells (I don't have enough to do the cell bus bars and man I'm tired of working on this thing lol). I also got all the wires in split loom and secured with strain reliefs.
BMS board with contactor, SSR, and Ethernet for CANBUS:
Other side of that board:
Looking down the cells from that board:
Breaker board:
Other side of breaker board:
Entire set:
Back of the set (this is 1 gauge wire temporarily, will be 3/0 in the RV):
That wire, BTW, supported the 9000 watt load with a +25F temp increase.