Shop & toolsCommon

Cordless drill

Also called driver, impact driver, tool pack.

A lithium pack with a weak group, a gearbox, and either a brushed motor or a BLDC with its controller. The charger is matched to the pack voltage.

A donor is the dead machine. The parts below are what is still worth removing from it. “Leave it” is a part that is physically in there and should stay in there: too dangerous, too worn, or only useful as part of a repair you are not doing.

A loose lithium cell

The flat end is negative, the button end is positive. Nominal voltage is about 3.6 to 3.7 volts. Full, for an ordinary cell, is 4.20 volts. Below about 2.5 volts for a long time, or any swelling, means it is for recycling, not for a project. Tape the ends so a bunch of them cannot short in a drawer.

Why it is in the trash while the parts are not

One cell group in the pack collapsed. The tool is often fine. Sometimes the trigger pot died.

Before you open it

Do this while it is still unplugged, cool, and not leaking. Tape cell ends as soon as they are apart. Do not solder the can. Swollen packs get recycled.

Lithium-ion cells

Where the dead machine usually is

Garage and shed — In the house
Repair-shop scrap — Commercial
Bulk trash day — Curb

The pack is at the curb; the charger is still on the shelf. They are a pair.

How it comes apart

Pack clamshell first. The tool's gearbox is a separate stack of planets.

Tools: Torx, Meter, Tape.

Words on this page

BLDC: Short for brushless DC motor. See brushless. The 'DC' does not mean you can hook it to a battery with two wires.

What to take

The table is the short version. The notes under it describe that part inside this machine, not only the general description.

Parts in this donor
Part	Call	How many	How often	Where to look
Cylindrical lithium-ion cell	Prize	3–10	usually	The pack.
Battery management board	Worth pulling	1	usually	In the pack.
Brushed DC motor	Worth pulling	1	sometimes	Older tools.
Brushless DC motor	Worth pulling	1	sometimes	Brushless tools.
BLDC controller	Worth pulling	1	sometimes	The handle.
DC gearmotor	Worth pulling	1	always	The front.
Potentiometer	Worth pulling	1	usually	The trigger.
Charger module	Worth pulling	1	usually	The charger.
Indicator LED	Bonus	1	usually	The work light.

Prize

Prize — take this firstCylindrical lithium-ion cell3–10 · usually
3S on 12 V class tools, 5S on 18/20 V. Often 2P or more.
The pack.
Measure each series group. Match before reuse.
One group bad is typical.

Worth pulling

Worth pullingBattery management board1 · usually
Or just a thermistor, on tools that do the protection in the tool.
In the pack.
Do not assume it protects.
Mixed.
Worth pullingBrushed DC motor1 · sometimes
A stout motor. Brushes are the wear item.
Older tools.
Check them.
Good.
Worth pullingBrushless DC motor1 · sometimes
Three phase plus halls.
Brushless tools.
Keep the controller.
Good.
Worth pullingBLDC controller1 · sometimes
Trigger is a pot plus a switch into this board.
The handle.
Keep the trigger.
Good if the pot is smooth.
Worth pullingDC gearmotor1 · always
Planetary gearbox. The whole point of the tool.
The front.
Do not lose the thrust washers.
Plastic planets strip on impacts.
Worth pullingPotentiometer1 · usually
Linear, plus a switch.
The trigger.
Smoothness test.
Wear is a common fault.
Worth pullingCharger module1 · usually
Output sits at the full pack voltage. 5S is about 21 V.
The charger.
Read the label. It is not a 12 V brick.
Good.

Bonus

Bonus, if you are already in thereIndicator LED1 · usually
A white LED.
The work light.
With its resistor.
Good.