Anmbest Constant Current CC CV Buck Converter Module DC 6-40V to 1.2-36V 20A 300W Adjustable Step Down Voltage Regulator Power Supply Module with Short Circuit Protection Function https://www.amazon.com/dp/B07R832BRX/ref=cm_sw_r_apan_glt_fabc_QFCSJTZAQF8TNKXRQ2QQ
fb marketplace has lots of milwaukee m18 connectors with wires cominf off of then grab a multimeter and find out which dial on the dc-dc converter controls output voltage until its between 12-14 volts, and the dial that doesnt ibfluebce volts crank it up...should have reliable 12v off of a m18 battery
Ok use this for the speed controller https://www.amazon.com/RioRand-7-80V-Motor-Controller-Switch/dp/B071NQ5G71/ref=sr_1_3
Use this to cut off the battery before it dipps to low. https://www.amazon.com/Digital-Battery-Low-Voltage-Protection/dp/B07929Y5SZ
And grab a 20 amp maxi fuse and a few insulated spade terminals.
Then find a small project box to run the thing in.
Ryobi batteries have a LV cut off battery cut off if thats what you are worried about. Why would you not run the M12 set up.
That said you can get these low voltage disconnects. if you want to avoid the over discharging them. Run the batteries on a tool till they are "dead" then measure the voltage. You need to set the low voltage cut off a few tenths of a volts higher than what they show.
I made a small switch box with LED’s for my son and I used this buck converter Buck Converter to get my 18v battery to 12v for the LEDs, unfortunately I didn’t know about the low voltage cutoff you linked above and it dropped the batteries voltage down to 12vdc, is there anyway to charge it back up? The charger is telling me the battery is broken but I used a 12v trickle charger and it still works for the LEDs I just can’t get the charger to fully charge it I’m assuming because it’s reading low voltage. Any help is appreciated. Thanks