Charger Troubleshooting
Edit on GitHubTP4056 faults: no charge light, slow charging, overcharging, and the input requirements that make the charger work at all.
Charger Troubleshooting
The TP4056 is simple, but its failure modes are specific: it needs the right input, and its status lights lie in ways you can learn to read.
The input requirements
| Requirement | Value |
|---|---|
| Input voltage | 4.5 - 5.5 V |
| Input current | At least 1 A for fast charging |
| Input quality | Clean DC; sagging inputs charge slowly or not at all |
A USB port that delivers 0.5 A charges a 2500 mAh cell at half rate. A wall adapter that “is 5 V” but sags to 4.2 V under load charges nothing. Test with the battery disconnected: the input should read above 4.5 V under load.
Reading the lights
| LED state | Meaning |
|---|---|
| Red on, green off | Charging |
| Green on, red off | Charged (or no cell!) |
| Blinking | Problem: check input, cell, or solder |
The classic false reading: green with no cell installed. Always confirm a cell is actually connected before trusting the green light.
Charging too slowly
| Cause | Fix |
|---|---|
| Weak USB source | Use a 1 A+ adapter |
| Wrong programming resistor | The Rprog resistor sets the current; 1.2 k = 1 A |
| Cold cell | The charger reduces current below 0 C (see Cold Weather Batteries) |
| Bad solder on the input pads | Reflow the joints |
Charging too fast / hot
A TP4056 at 1 A into a cold or aged cell heats up. The board should be warm, not hot. A hot board means: wrong Rprog, a shorted cell, or a counterfeit module. Stop, disconnect, inspect.
The full-cycle test
- Connect an empty, healthy cell.
- Confirm red light, note the time.
- At full charge (green), disconnect and measure the resting voltage: 4.15 - 4.22 V is correct. Above 4.25 V repeatedly means a faulty charger board: replace it.
Related pages
- TP4056 Charger Guide for the module
- TP4056 Wiring for the circuit
- Battery Troubleshooting for the cell side