5PCS 1S 3.7V 4A 18650 Charger PCB BMS Protection Board for Li-ion Lithium Battery Cell

i did the 18650s because two AA or AAA will start out a 3v and go down from there. Button cells are usually 3.7ish when fresh. So the AA or AAA wont last as long. I have not had any sensor die on me yet from the voltage. only from hooking them up backwards. Remember coin cell polarity is opposite of what you expect. No buck converter. just a parallel dual 18650 holder, then soldered to a 1 cell BMS, and then the wires out to the device. i use lever locks (wagos) to connect devices so i can expand easily if needed. BMS https://www.amazon.com/dp/B07KSPYMJ2 Dual 18650 holder https://a.co/d/0cStWQQI Front https://8upload.com/view/658fb7745bab Back https://8upload.com/view/752a91f4e6a4 In use https://8upload.com/view/3903c7a58d44