Energy storageRebuild shelfHand tools, works as-is

Coin cell

Also called CR2032, CR2025, CMOS battery.

The CMOS battery on a motherboard and the cell in a remote, a scale, a bike computer. CR2032 is 3 V lithium, 20 mm. Holders are more useful than a half-dead cell.

If you are new to this category

Batteries store energy. The useful ones in modern scrap are lithium cells, and they are also the ones that burn if they are crushed, overcharged, or wired together carelessly. A pack is usually thrown out because one cell in the chain is weak, not because every cell is dead. Swollen means stop.

Tape over bare metal ends as soon as a cell is loose. Charge only with a charger made for that chemistry and that number of cells in series.

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.

Lithium-ion cells. A punctured, crushed, overcharged, or reverse-charged cell vents and burns hot enough to ignite the bench. Swollen pouches are already failed.

Specification. The right-hand column is what is typical. The label on the part in your hand wins if they disagree.
What to look for	Usual figure
CR2032	3.0 V, about 220 mAh, not rechargeable. ML2032 looks identical and is rechargeable. Do not charge a CR.
Holder	Motherboard holders are a free 20 mm socket

Volts are electrical pressure, amps are how much current is flowing, and ohms are how hard the part resists that flow. A higher voltage than the part was built for is how salvage parts die on the bench. If a cell in the table says “read the stamp”, that stamp is the whole specification.

What people actually use it for

Real-time clocks
A memory backup
The holder, even if the cell is flat

Leave this one when

It has been leaking (alkaline LR44 cousins do this). Clean the corrosion; bin the cell.

Buying a new one is the better idea when

Coin cells are cheap and dated. Keep holders, buy fresh cells.

How to tell if this one still works

Voltage. Under about 2.7 V, a CR2032 is due for replacement in a real product.

Tools you will want: Meter.

Where people actually find it

5 notes, most useful first. “Leave it” means the part is in that machine and you should not take it: it is dangerous, worn out, or only useful if you already know that exact repair.

Harvest at a glance
From	Call	How many	How often	Where it sits
Desktop PC	Worth it	1	usually	Motherboard, near the southbridge area.
Laptop	Bonus	1	usually	A small yellow-wrapped cell or a holder on the board.
Digital kitchen scale	Bonus	1	sometimes	The battery.
Infrared remote	Bonus	1	sometimes	Some remotes.
Doorbell	Bonus	1	sometimes	Wireless buttons.

Worth pullingDesktop PC1 · usually
In this particular machine
CR2032 in a holder. The holder is the part.
Where to look
Motherboard, near the southbridge area.
How to get it out
Pop the cell. The holder desolders if you actually want it.
The condition to expect
The cell is often near the end of its life. The holder is not.
Bonus, if you are already in thereLaptop1 · usually
In this particular machine
CMOS backup.
Where to look
A small yellow-wrapped cell or a holder on the board.
How to get it out
Unplug it. Some are soldered packs.
The condition to expect
Often flat. The connector is what you learn from.
Bonus, if you are already in thereDigital kitchen scale1 · sometimes
In this particular machine
CR2032.
Where to look
The battery.
How to get it out
Test the voltage.
The condition to expect
Often flat.
Bonus, if you are already in thereInfrared remote1 · sometimes
In this particular machine
CR2032.
Where to look
Some remotes.
How to get it out
Test.
The condition to expect
Flat.
Bonus, if you are already in thereDoorbell1 · sometimes
In this particular machine
A coin cell.
Where to look
Wireless buttons.
How to get it out
The radio is not a useful module.
The condition to expect
Flat.