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Drill battery pack as power bank
Power drill battery packs commonly use 18650 LiPo cells (5x for 18V) and some PCB with or without logic and/or protection circuit.
See what is inside various power packs here: https://www.werkzeug-news.de/threads/welche-akku-zellen-sind-bei-welchem-hersteller-verbaut-innenleben-akkupack.39500
As one of mine is unused as of now, I want to use it as USB-C juice for my notebook and Pinecil soldering iron too.
DIY Power Bank PCB options
There are ready to use fast charging buck modules with USB-C PD 65W (supporting QC too) for cheap ~1.2€, whose output voltage is ⇐input voltage (the buck only ones) - not a power bank module so charging the battery is not possible.
To be able to charge the battery pack too, I am going for a bidirectional IP2369 board with 45W on PD (which is cheaper than IP2368 100W version). As it is a power bank IC, it has the advantage that it can charge the 1-6 cells, configurable by resistor. It is buck+boost so no matter how many cells you use, there will be 20V for PD.
Why not just buy a power bank board with enclosure for the 18650 cells? Well, then I had to disassemble the battery pack and not be able to use it with a drill anymore.
FYI: read about battery tips and LiPo charger boards
Battery packs
Vendors use different battery packs for drills, even though there are standards for interchangeable, compatible connections.
source: xkcd.com/927/
So what we are going to do is 3D print an adapter for the connection to our power bank module.
J.C. Schwarz battery pack conversion
Inside are 5x 18650 Samsung cells. I got them cheap in a sale (I do not even own a compatible drill).
The PCB only has passive components
| Pin | Name | description |
|---|---|---|
| 1 | C+ | Charge positive terminal (charger input +). Separate so the pack BMS can control charging |
| 2 | B+ | battery positive (power out to the tool) |
| 3 | unlabled | most likely thermistor (NTC) |
| 4 | LS | “Load Sense” / ID / enable / data pin. Used by the tool or charger to verify the pack (resistor ID) or to wake/enable the pack’s protection FETs. Often called T, ID, Data or T-sense on different brands. |
| 5 | B- | Ground |
| 6 | LD (unpupulated) | unused |
#TODO: 3D printing model
Bosch Professional 18V
Bosch professional = blue
https://toolcroze.com/bosch-18v-battery-wiring-diagram-pinout/
https://www.mikrocontroller.net/topic/476801
Uses 0.75mm nickel-plated plates as contacts.
Bosch consumer 18V
Bosch “consumer” (aka Bosch Home and Garden) = green