How to Use the TP4056 Boost Module for 3.7V Projects

By Kunkune | Published: 2026-11-01

Category: How-to Guides

Wire a TP4056 boost module to charge and power 3.7V projects safely. Follow the step-by-step setup, avoid load-sharing mistakes, and get a stable 5V output.

Quick answer

Use a TP4056 boost module to charge a single 18650 cell and deliver a regulated 5V output for your 3.7V project. Wire the battery to the board's BAT pads, connect your load to the boost output, and never connect the load directly to the battery while charging unless you add a proper load-sharing circuit.

Why the boost module needs a clean battery connection

The TP4056 boost module combines a lithium-ion charger and a step-up converter on one board. The charger section expects a single 3.7V cell, and the boost section raises that voltage to 5V for your project. Because both functions share the same battery, the quality of your battery wiring directly affects charging stability and output voltage.

Use short, thick wires between the battery and the BAT pads. Long or thin wires add resistance that can cause the charger to misread the battery voltage, leading to incomplete charges or premature termination. Solder the wires firmly and insulate the connections before powering up.

When to add a load-sharing circuit

If your project draws current while the battery is charging, the charger sees both the battery and the load. That can confuse the charge termination and, in some cases, overcharge the cell. A load-sharing circuit—often built with a P-channel MOSFET and a Schottky diode—disconnects the load from the battery during charging and powers the project from the input source instead.

For projects that only charge when the load is off, you can skip load sharing. But if you plan to run an Arduino or sensors continuously while plugged in, treat the load-sharing circuit as required, not optional.

What the module does not include

This board does not include a battery protection circuit. Many 18650 cells have built-in protection, but bare cells do not. Without protection, a short circuit or over-discharge can damage the cell or create a safety hazard. If your cell lacks a protection PCB, add an external protection module between the battery and the TP4056 board.

The module also lacks a mounting hole pattern or terminal blocks in most versions. Plan to solder wires directly or use a small perfboard to secure the board inside your enclosure.

Step-by-step TP4056 boost module setup

Prepare the battery and check for protection: Confirm your 18650 cell has a protection circuit. If it does not, solder a protected 18650 or add an external protection board. Never use a bare, unprotected cell without additional protection. A protected cell is the first safety checkpoint.
Solder the battery wires to the BAT pads: Solder the red wire from the battery positive to the BAT+ pad and the black wire from the battery negative to the BAT- pad. Keep the wires short and thick. Double-check polarity before connecting the battery. Reversed polarity will destroy the board instantly.
Connect the load to the boost output: Solder your project's positive input to the VOUT+ pad and the negative input to the VOUT- pad. The boost output provides a regulated 5V, so connect only devices that accept 5V. Do not connect the load to the BAT pads. The BAT pads are for the battery only; the load goes to VOUT.
Add load sharing if the project runs while charging: If your project must operate during charging, build a load-sharing circuit using a P-channel MOSFET and a Schottky diode, or use a dedicated load-sharing module. Without it, the charger may not terminate correctly. Load sharing protects the battery when charging and running at the same time.
Power up and verify the output voltage: Connect the battery and measure the voltage at VOUT with a multimeter. It should read close to 5V. Then connect your project and check that it powers on. If the voltage drops significantly under load, your battery may be discharged or the boost module may be overloaded. A stable 5V reading confirms the boost section is working.
Charge the battery through the USB port: Plug a USB cable into the module's input port. The charge indicator LED should light. Charge current is typically fixed, so avoid charging from a weak USB source. Disconnect the load during charging unless you have a load-sharing circuit. Never leave a charging battery unattended for long periods.

Product facts

Battery Charger Board 18650 Lithium Li-ion 3.7V 4.2V DC-DC Step Up Boost Module TP4056: Battery Charger Board 18650 Lithium Li-ion 3.7V 4.2V DC-DC Step Up Boost Module TP4056 This board combines charging and 5V boost in one module, so you need only one board for a compact 3.7V project.
Battery Charger Board 18650 Lithium Li-ion 3.7V 4.2V DC-DC Step Up Boost Module TP4056