Single 18650 charger with LED charge indicator
Charges one cell from USB; red while charging, blue when full. Charge one Li-ion 18650 cell safely from USB: the TP4056 board does constant current (1 A) until the cell reaches 4.2 V, then holds 4.2 V while the current tapers. Its red LED is lit while charging and the blue one when it has finished.
Build it in the labGuided build, test sheet and fault finding, free in your browser.
Parts list
- Bench power supply
- TP4056 charger module
- 18650 Li-ion cell
Test procedure
Each test has an expected value and a pass range, like a factory test sheet:
- Constant current, cell at 3.6 V
- Red LED while charging
- Full-charge voltage
- Blue LED when full
How it works
What it does: Charges one cell from USB; red while charging, blue when full.
Build it (guided or ready-made), then run its test procedure below. Every test has an expected value and a pass range, just like a factory test sheet.
Background
The first thing most makers build for their 18650s, and the heart of every power bank.