What each pin actually does on a B&D 20V pack

[Thomas Martinez]

Found a pinout diagrams for B&D 20V batteries and thought it’d be worth posting. Pretty much all the rest of the posts out there are pretty generic, mostly just + and -.
Minus is the negative terminal, plus is the positive. Then there’s an ID pin that the tool use to identify the battery. That pin is presumably a resistor that tell the tool what resistance to expect from the battery (how most brands do it). Then there’s a thermistor pin (TH) that tell the tool the battery temperature. Then there are four junction (C1-C4) that connect the cell groups (the BMS checks these during charging).
It’s basically the same as almost every other 20V Max battery platform out there. The cheap brands all seem to use the same layout for the ID, thermistor, and cell junctions for the BMS to read.
So is the ID check strict on Black and Decker products? What resistor value does it use for the ID pin? Has anyone probed a Black and Decker battery to find out what goes on with the ID pin?

 

[Shiny Shark]

The ID on b&d packs is just a resistor to ground. It’s around 7.5k on the standard 20v packs but thats from memory from one pack I checked

 

[Mist]

Has anyone actually scoped the ID pin on Black and Decker batteries on startup with an oscilloscope? Does it sample the resistance from the ID pin? Does it use a standard 10k NTC as a thermistor?

 

[Victoriou]

Has anyone actually scoped the ID pin on Black and Decker batteries on startup with an oscilloscope? Does it sample the resistance from the ID pin? Does it use a standard 10k NTC as a thermistor?

It’s a 10k ntc, same as every other pack on the market. No one is reinventing the wheel for a thermistor

 

[Obedient Oyst]

These cell taps is a godsend when trying to rebuild packs. I salvaged a dead 4ah pack last summer. Two of the cells were dead in the pack and the BMS latched off. I charged each of the cells individually with a hobby charger, then reconnected the pack and the BMS came back online. Works great since the cells is in the same configuration as with the factory pack. B&D 20v packs are some of the easiest to work on because there isnt nothing tricky about any of them.

 

[Tired Teira]

who cares just buy a new pack lol

 

[Mist]

It’s a 10k ntc, same as every other pack on the market. No one is reinventing the wheel for a thermistor

If the tool just measures the resistance of the ID pin on startup then it is possible to fake the ID pin by simply using a resistor between the pin and ground. Has anyone used a benchtop power supply to power Black and Decker tools with the ID pin provisioned with a resistor?

 

[Amused Albatross]

If the tool just measures the resistance of the ID pin on startup then it is possible to fake the ID pin by simply using a resistor between the pin and ground. Has anyone used a benchtop power supply to power Black and Decker tools with the ID pin provisioned with a resistor?

Yes people do this all the time when testing the battery. Connect the power supply to the +/- terminals on the pack and drop a resistor on the ID pin. Also short the TH pin to ground through another 10k and the tool will fire right up.

 

[Shiny Shark]

Yes people do this all the time when testing the battery. Connect the power supply to the +/- terminals on the pack and drop a resistor on the ID pin. Also short the TH pin to ground through another 10k and the tool will fire right up.

If you just short the TH pin to ground the tool will think the battery is freezing cold and refuse to run on some models. It has to be within a certain range to start.

 

[Inquisitive Iguana]

I mapped out a Black and Decker pack last year when I was rebuilding a battery for my father in law. The ID pin on his sawyer was 7.68k measured and the thermistor was a 10k NTC reading out to around 9.8k at room temperature. The tool did not care what cells I used for his sawyer as long as the two pins matched what they read on the battery. So the tool just measured a window for the resistance on the ID pin and the thermistor value.

 

[Courageous Cat]

alot of people miss that the BMS uses the cell taps during charging, not the tool. The tool does not measure each cell voltage, only the charger does.

 

[Tired Teira]

b&d is garbage anyway, the dewalt 20v packs are the same size and last 3x as long

 

[Elegant Eel]

b&d is garbage anyway, the dewalt 20v packs are the same size and last 3x as long

they are absolutely NOT the same form factor. Dewalt and B&D 20v max tools will not accept each other’s batteries. The stems are different sizes, the latch on the tool is different, and the contact points on the battery are not the same.