Energy storageBench electronicsTest and identify

Charger module

Also called TP4056, charge board, tool charger.

A TP4056-style single-cell charger shows up in cheap Bluetooth speakers and power banks. Tool chargers are a matched pair with that tool's pack voltage. Neither is a universal lithium charger.

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 sealed supply versus an open board

Left: a brick. The label is your spec, and the plastic is the safety barrier. Right: a board taken out of a lamp or a charger. Unless you have checked that the output is isolated from the prongs, do not let it touch a project you will handle while it is plugged in.

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.
Mains voltage. Line voltage, and the DC bus just after the rectifier, both kill. A disconnected cord is not a discharged supply.

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
TP4056	1S, CC/CV to 4.2 V, charge current set by a resistor, often 1 A. Needs a protection board; the classic module does not include one unless it is the version with DW01.
Tool charger	Output is the pack voltage: about 21 V for a 5S 18 V pack, about 12.6 V for 3S. The label is the spec.

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

Charging the chemistry and series count it was built for

Leave this one when

You wanted one charger for every battery you own. That device does not exist in the trash.

Buying a new one is the better idea when

A charger with a display that shows what it is doing to each cell.

How to tell if this one still works

Meter the output voltage with no battery. A 1S charger should sit near 4.2 V. A tool charger should sit near its labeled DC voltage, not at mains.

Step-by-step on the bench: Check a supply is actually isolated

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.

mains: Ordinary household wall power. It can kill. Unplug before you open anything that used it, and do not experiment on live wiring.

Where people actually find it

3 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
Cordless vacuum	Worth it	1	usually	The dock.
Cordless drill	Worth it	1	usually	The charger.
Powered or Bluetooth speaker	Bonus	1	sometimes	With the cells.

Worth pullingCordless vacuum1 · usually
In this particular machine
Matched to the pack.
Where to look
The dock.
How to get it out
Read the label.
The condition to expect
Good.
Worth pullingCordless drill1 · usually
In this particular machine
Output sits at the full pack voltage. 5S is about 21 V.
Where to look
The charger.
How to get it out
Read the label. It is not a 12 V brick.
The condition to expect
Good.
Bonus, if you are already in therePowered or Bluetooth speaker1 · sometimes
In this particular machine
1S or 2S charger.
Where to look
With the cells.
How to get it out
Read it before you trust it.
The condition to expect
Good.