Overview
The TP4056 charging module is arguably the most ubiquitous lithium battery charging solution in the maker community. At prices often below $0.50 per unit, these boards offer an incredibly low barrier to entry for battery-powered projects. However, the low cost comes with trade-offs that every user should understand.
The TP4056 IC itself is a capable linear charger with proper CC/CV charging profile for lithium cells. The issues arise primarily from the implementation on cheap PCBs: thermal management, component quality, and protection circuit effectiveness.
Two variants exist: the basic version with just the TP4056, and the "protected" version adding DW01A + FS8205A for over-discharge, over-charge, and short-circuit protection.
Technical Analysis
Charging Performance
The TP4056 implements a standard CC/CV charging algorithm:
- Constant Current phase: Charges at programmed current (default 1A) until battery reaches 4.2V
- Constant Voltage phase: Holds 4.2V while current tapers
- Termination: Charging stops when current drops to ~1/10th of programmed current
Measured performance across 10 test units:
| Parameter | Spec | Measured Range |
|---|---|---|
| Charge Voltage | 4.2V ±1.5% | 4.18-4.23V |
| Charge Current | 1000mA | 850-1050mA |
| Termination | ~100mA | 80-130mA |
Thermal Concerns
Heat Dissipation
At 1A charge current with 5V input, the TP4056 dissipates approximately 0.8W as heat. The small PCB and minimal copper area make thermal management challenging.
Measured temperatures during 1A charging:
- Ambient 25°C: IC reached 65-75°C
- Enclosed space: IC exceeded 85°C (thermal shutdown threshold)
The thermal pad under the TP4056 is often poorly connected to the ground plane, reducing heat dissipation effectiveness.
Protection Circuit Analysis
The "protected" version adds:
- DW01A: Protection IC monitoring voltage and current
- FS8205A (or 8205A): Dual MOSFET for disconnect
Critical Finding: On several tested boards, the PCB traces between the protection MOSFETs and battery terminals were only 0.3-0.5mm wide—insufficient for the rated 3A short-circuit protection current. These traces would act as fuses before the protection IC could react.
Key Findings
- Charge voltage accuracy is generally acceptable (within 1.5% spec)
- Thermal performance is marginal at full 1A rate
- Protection circuits may not function as rated due to PCB limitations
- USB connector mechanical quality is poor
- Some units use counterfeit or remarked ICs
Testing Results
Batch Comparison
| Seller | Units | Working | Voltage Accuracy | Protection Working |
|---|---|---|---|---|
| Seller A | 5 | 5/5 | ±1% | 4/5 |
| Seller B | 3 | 3/3 | ±2% | 2/3 |
| Seller C | 2 | 2/2 | ±1.5% | 1/2 |
"Protection Working" was tested by intentionally shorting the output—boards with inadequate traces showed trace damage rather than clean MOSFET cutoff.
Long-term Reliability
Five modules used for weekly charging cycles over 6 months:
- 1 failed (USB connector detached)
- 1 showed degraded charge current (down to 600mA)
- 3 functioning normally
Recommendations
Use these modules when:
- Prototyping on the bench with supervision
- Charge current reduced to 500mA or less (change PROG resistor)
- Adequate ventilation is provided
- Additional external protection is added for critical applications
Avoid these modules when:
- Charging unattended or overnight
- Enclosed in cases without ventilation
- Used in products for sale (liability concerns)
- Maximum reliability is required
Suggested Modifications
- Reduce charge current: Replace 1.2kΩ PROG resistor with 2.4kΩ for 500mA, or 10kΩ for 130mA
- Add thermal relief: Attach small heatsink or ensure copper pour connection
- External fuse: Add 2A polyfuse in series for true short-circuit protection
- Reinforce USB: Add hot glue or strain relief if using USB connector
Alternatives
For production or safety-critical use, consider:
- MCP73831: Single-cell charger with better thermal performance
- BQ24072: More expensive but includes power path management
- Dedicated charger ICs: From reputable distributors with proper reference designs