Description
The Under-Voltage Cutoff board exists to disconnect the battery if the voltage falls below a certain threshold. It provides a few additional protection features, including a fuse to limit short-circuit current, inrush-current limiting, and reverse polarity protection.
It also has load switches to control the loads (fans and horn). The load switches have built-in current sensing. UV Cutoff interfaces with power distribution to control the load switches and to provide power to the comparator.
In rev 2, a "fuel-gauge" IC was added (might be to measure the SoC more accurately)
Possible Action Items
Read up on and analyze previous revs of UV Cutoff
Add a charging circuit?
Will also require active protection (over-voltage, over-temperature, and overcurrent, see section 8.3.B in ASC regs)
Make UV cutoff compatible with aux battery?
Use the same PCB for both batteries, but some passives might need to change to adjust reference voltages, etc.
Replace the high-side P-channel MOSFET reverse polarity protection with a low-side N-channel MOSFET for reverse polarity protection.
N-channels have a lower on resistance, so it would be more efficient. It would also be safer on the low side. If the battery was connected backwards with a P-channel FET, then 12 V will be connected to gnd, which is a larger net so it's more likely to accidentally touch something conductive and cause a short circuit.
The fuse could probably be replaced with an e-fuse to have a more precise current limit.