The TP4056 1A 18650 lithium‑ion battery charger module is an ultra‑popular, compact charging board commonly used for DIY electronics projects(see DIY +5V Regulated Power Supply).
Here's a breakdown of its components and functionality:
⚡ 1. Charging IC – TP4056
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It uses the TP4056 (or TC4056A) chip, a stand-alone constant current / constant voltage (CC/CV) linear charger IC.
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Designed for USB-powered 5 V input, typically charging at up to 1 A, with a default charge termination at 100 mA (C/10).
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Automatically ends charging when the current drops to about 1/10th of the programmed rate, and supports trickle charging for deeply discharged batteries below ~2.9 V.
🛡️ 2. Protection Circuit – DW01A & FS8205A MOSFET
Most modules include a battery protection IC (DW01A) and a dual MOSFET (FS8205A) to safeguard the battery. This adds protection against:
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Over-charge: Cuts off at ~4.3 V.
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Over-discharge: Turns off if voltage drops below ~2.4 V, reconnecting at ~3.0 V.
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Over-current / short-circuit: Latch-off if current >3 A.
🔌 3. Interface & Control
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Accepts input via Micro‑USB or USB‑C, plus solderable pads.
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Has LEDs: Red = charging, Blue or Green = fully charged.
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Charge current set by resistor (Rprog); default ~1 A but can be adjusted with a different resistor.
✅ 4. Typical Specs
| Feature | Value |
|---|---|
| Input Voltage | 4.5 – 6 V |
| Charge Voltage | 4.2 V ±1.5% |
| Default Charge Current | ~1 A (programmable) |
| Trickle Charge Current | ~130 mA |
| Over-discharge Cutoff | ~2.4 V |
| Over-current Trip | ~3 A |
| Size | ~28 × 17 mm (standard) |
⚠️ 5. Limitations & Safety Notes
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Linear charger inefficiency & heat
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It's a linear regulator: excessive power is dissipated as heat. E.g., charging at 500 mA from 5 V to 3.7 V can generate ~0.75 W of heat.
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This can lead to high temperatures (40–45 °C), particularly problematic in confined spaces or when in contact with the battery.
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No power path / "load sharing" by default
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If you power a device while charging the battery, the TP4056 may misinterpret battery current and fail to terminate properly, leading to prolonged trickle charging, which is harmful over time.
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Potential for overcharge if misused
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Continuous operation at float voltage with a connected load can prevent the charger from correctly stopping and stress the battery.
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✅ 6. Ideal Use Cases
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Single-cell 18650, 14500, or other small-format Li‑ion cells.
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Projects like DIY power banks, flashlights, or small robotics—when charging and power loads are separated or when you handle thermal management.
🔧 Modifications & Alternatives
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Add power path or load sharing circuit: Some users (e.g., on Arduino forums) add extra MOSFET/diode arrangements to allow safe charging while the device is running.
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Use a switching (buck) charger with power path if you need higher efficiency and simultaneous load‑charge support.
The output voltage between the battery terminals of a TP4056 1A lithium battery charger module is:
🔋 Between 3.0 V and 4.2 V, depending on the battery charge state.
Here's what happens:
| Battery Condition | Output Voltage (V) |
|---|---|
| Deeply discharged | ~2.5 V–2.9 V |
| Normal discharge range | 3.0 V – 3.7 V |
| Fully charged | 4.2 V |
| Charging (CC mode) | Increasing up to 4.2 V |
| Charging (CV mode) | Maintains 4.2 V |
⚠️ Important Notes:
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The charger outputs whatever voltage is on the Li-Ion battery; it does not regulate the output once the battery is connected.
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If your application is connected to the battery terminals, your device will receive the raw battery voltage, which drops gradually as the battery discharges.
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To get a regulated 5V or 3.3V output, you must add a boost converter or LDO regulator after the battery.
