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⚠️UNDER CONSTRUCTION!⚠️⚠
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. 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 take IP2368 100W version? Well, it is more expensive and needs connections between each cell, which would defeat the purpose of not taking the battery pack apart. Then you can just put the 18650 cells into a “DIY power bank enclosure” with board.
FYI: read about battery tips and LiPo charger boards
Add USB-A to IP2368
The bidirectional IP2368 board I've chosen has only one USB-C port. Looking at the datasheet, you can see how USB-A is added the proper way.
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