2-Pack 70A Discharge Protection Boards, Compatible with DeWalt & Milwaukee 18V-20V MAX Batteries, Featuring Low Battery Discharge Cut-Off & Overheat Safety, BMS Only, Not for Charging

I used this discharge protection board I found on Amazon. It has fairly mixed reviews but has worked well enough for me.

I used this board Amazon. It has mixed reviews, but it does shut off when I drop the voltage from my desktop power supply. I run both the light and USB charger of the 18ish volts directly from the battery, as both are rated for 12-24 volts.