How to Power ESP32 with 18650 Batteries
In this guide, we’ll show you exactly how to power ESP32 using 18650 batteries safely, efficiently, and without damaging your board.
Why Use 18650 Batteries for ESP32?
18650 batteries offer:
- High capacity (2000–3500mAh+)
- Rechargeability
- Portability
- Low cost
- Ideal for outdoor and remote ESP32 projects
But you must power the ESP32 correctly to avoid voltage issues or permanent damage.
Understanding ESP32 Power Requirements
The ESP32 chip runs at 3.3V and must not receive more than 3.6V directly.
Most ESP32 development boards (like the ESP32 DevKit V1) come with an onboard AMS1117-3.3 voltage regulator, which allows you to power the board with higher voltages (like 5V or more) through the 5V or VIN pin.
Can You Connect a Single 18650 Battery Directly?
A single 18650 battery outputs:
- Nominal voltage: 3.7V
- Fully charged: 4.2V
- Discharged: ~3.0V
⚠️ Directly connecting one 18650 to the 3.3V or VIN pin is not safe:
Connection | Safe? | Reason |
---|---|---|
18650 → 3.3V pin | ❌ Never | Will burn the chip |
18650 → VIN/5V pin | ⚠️ Risky | Voltage may drop too low or rise too high |
Best Way: Use 2x 18650 Batteries in Series
This method outputs 7.4V–8.4V, which is perfect for feeding the 5V pin or VIN pin on ESP32 boards with an AMS1117 regulator.
You Need:
- 2x 18650 batteries (same brand/capacity)
- Battery holder (2-cell, series configuration)
- AMS1117-equipped ESP32 board (like DevKit V1) -----> THIS IS IMPORTANT
- Optional: TP4056 charger module with protection
Wiring Diagram
Here's how to connect:
- Battery Holder Output (+) → ESP32 5V pin
- Battery Holder Output (–) → ESP32 GND

AMS1117 will regulate 7.4V–8.4V down to 3.3V, perfect for the ESP32 and any connected peripherals.
⚠️ Important Safety Tips
- Never exceed 12V input on VIN/5V pin
- Use protected 18650 batteries to avoid overcharge/discharge
- Avoid connecting batteries to the 3.3V pin
- Consider using a switch or power button
- Use a TP4056 charging module to recharge safely
Alternative Method: Boost Converter with 1x 18650
You can also use a DC-DC boost converter (like MT3608) to step up one 18650 battery from 3.7V to 5V.
Pros | Cons |
---|---|
Uses 1 battery | More components |
Adjustable output | Boost converters may introduce noise |
Battery Life Estimation
With two 3000mAh 18650s:
- Average ESP32 consumption: ~150mA (Wi-Fi active)
- Approximate runtime: 30–35 hours
You can extend battery life by:
- Using deep sleep mode
- Disabling unused sensors/modules
- Reducing Wi-Fi/Bluetooth activity
Conclusion
Powering your ESP32 with 18650 batteries is one of the best power solutions for mobile IoT projects. Just remember:
- Use 2x 18650 in series for stable power through the 5V or VIN pin
- Always check your board has an AMS1117 regulator
- Protect your batteries and regulate voltage properly
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