Cracked open my Craftsman 20V pack, here's what each pin does

May 5, 2026
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toolcroze.com
Got myself a dead Craftsman 20V to peek inside of before tossing it in the bin. Used a meter to poke around and see what each pad on the BMS did, so dumping this info in case others is wondering what each labeled pads does on one of these tools.
B- and B+ obviously go to the cell. ID is the line the tool use to identify the battery. TH is the thermistor pin for temperature monitor of the battery pack. C1-C4 is taps between each cell group to balance each group of cells.
Nothing too fancy, but its somewhat standard out there in the battery world. The label on the battery pack, however, are not always obvious to those of us who havent opened too many of these packs. The other question that I had was if the ID pin is just a resistor or if there is data on that pin. Unfortunately, too far gone on my battery to test under a load. Also yet to confirm what the value of the thermistor is; didnt want to pull it off the battery. Does anyone knows more about this pin/line specifically? If so, I’d love to hear from you. I’m attempting to try and revive this tool with new cells. Anyone else done this yet?


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The ID line on most of these knockoff tier battery packs is just a resistor to ground. Usually a 10k or 22k resistor. The tool read the value of this resistor to decide if your using a genuine tool and battery pack. Since Craftsman tools is mostly just rebadged Stanley and B&D tools under the SBD umbrella, its likely the same with the Craftsman tools as well.