DIY Rechargeable Power Supply with TP4056 and MT3608

Combine a Li-ion charger board and a boost converter into a rechargeable 5V–12V supply for all your breadboard projects.

What you’ll build

The TP4056 safely charges a single Li-ion cell (from any USB port) and protects it from over-discharge. Its output feeds an MT3608 boost converter that steps the cell’s 3.0–4.2V up to a rock-steady 5V (or up to 24V) for your projects — a bench supply that fits in your pocket. Pair it with an 18650 cell (locally sourced).

Components you’ll need

Step-by-step guide

1. Solder your Li-ion cell (an 18650 with tabs is easiest) to the TP4056’s B+ and B− pads.
2. Connect the TP4056 OUT+ / OUT− pads to the MT3608 IN+ / IN−, with the slide switch in the OUT+ line as a power switch.
3. Screw terminal blocks onto the MT3608 output for easy hookup to any project.
4. Charge via the TP4056’s USB port: red LED while charging, blue when full.
5. Power on and slowly turn the MT3608’s trim pot while measuring the output with a multimeter until it reads exactly 5.0V (or whatever your project needs).
6. Label the output voltage on the case — future-you will be grateful.

The code

No code this time — this is a pure hardware build. As a bonus, here is the one-line rule that keeps Li-ion cells happy:

Charge at 0.5C or less, never discharge below 3.0V,
and never leave a charging cell unattended.

The TP4056 handles the first two automatically —
the third one is on you.

The complete, ready-to-upload sketch and wiring diagram are on GitHub: