Energy storageBench electronicsSpecialist reuse

Lithium pouch cell

Also called LiPo, phone battery, laptop pouch.

A soft lithium cell. Energy density is good and the mechanical protection is a plastic bag. Phone and laptop packs, Bluetooth speakers, headphones. Swollen means the cell has already generated gas. It is end of life.

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
Voltage	Same 3.6–3.7 V nominal per series cell as cylindrical, unless the label says otherwise
Laptop	Often 3S or 4S with a BMS board in the pack. The connector pinout is model-specific and includes a data line you can ignore only if you understand which pin is which.
Damage	A crease, a puncture, or a spicy pillow is a recycling job

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

The same device
A low-current project if the cell is flat, tested, and protected

Leave this one when

Any swelling, any puncture, any unknown BMS pinout you are about to guess.

Buying a new one is the better idea when

A protected pouch with a known capacity, if you do not already need this exact shape.

How to tell if this one still works

Voltage at the pack output if the BMS is awake. Do not pierce the foil to measure an internal cell.

Step-by-step on the bench: Sort salvaged lithium cells

Tools you will want: Meter.

Words on this page

Short meanings, so the rest of the entry is readable if you are not already doing this every weekend.

BMS: Battery management board. The small circuit that cuts a lithium pack off if it is too full, too empty, or drawing too much current. It has to match the number of cells.
nominal: The nameplate voltage, not the exact voltage at every moment. A '12 V' lead-acid battery sits around 12.6 V when full and sags under load.
series: Connected in a chain. Cells in series add their voltages. LEDs in series all go dark if one of them opens.

Where people actually find it

4 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
Laptop	Prize	1 pack	usually	Inside the shell.
Mobile phone	Worth it	1	sometimes	Under the cover.
Headphones	Bonus	1	sometimes	Wireless models.
Digital camera	Bonus	1	sometimes	The battery.

Prize — take this firstLaptop1 pack · usually
In this particular machine
3S or 4S is typical, with a BMS board in the pack.
Where to look
Inside the shell.
How to get it out
Unplug the pack before other cables. Do not crease it.
The condition to expect
Swollen is recycle. Flat and still above 3 V per cell is testable.
Worth pullingMobile phone1 · sometimes
In this particular machine
A thin pouch with a protection board.
Where to look
Under the cover.
How to get it out
Only if it is flat, not spicy, and holds voltage.
The condition to expect
Swollen is recycle.
Bonus, if you are already in thereHeadphones1 · sometimes
In this particular machine
A tiny pouch.
Where to look
Wireless models.
How to get it out
Only if it is not swollen.
The condition to expect
Often tired.
Bonus, if you are already in thereDigital camera1 · sometimes
In this particular machine
A proprietary pack with a BMS.
Where to look
The battery.
How to get it out
Test. Do not peel it.
The condition to expect
Often tired.