01Safety first: when not to try
When a power bank won't charge, the fix is usually a cable, a charger, or patience. But first rule out the one situation where you shouldn't try at all.
A bulging case, a sweet or chemical smell, hissing, or heat when it isn't charging all point to damaged lithium cells. Don't charge it, press on it or puncture it. Put it on a non-flammable surface away from anything that burns, and take it to a battery recycling drop-off. Never put it in household trash.
If it looks and feels normal, carry on. Everything below is safe to try.
02Revive a power bank that won't charge
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Find the real input port
Some banks have separate input and output ports. Look for IN, INPUT, or an arrow pointing into the bank. On banks with one USB-C port, that port handles both directions.
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Swap the cable
The cable that ships with a power bank is often short and thin. Try a cable that charges your phone properly from the wall. A worn cable is the single most common cause.
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Swap the charger
Laptop USB ports, car sockets and old 5W cubes may not supply enough. Use a wall charger. If the bank has a USB-C PD input, a 20W or higher USB-C PD charger is the right match.
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Give it time
When a lithium battery is drained very low, its protection circuit can shut the bank down completely. Many banks will slowly recover if you leave them on a charger for 30 to 60 minutes before the lights respond. A basic 5V charger sometimes wakes a bank that a fast charger won't.
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Unplug everything from the outputs
Some banks won't charge, or charge very slowly, while they're also charging a phone. Disconnect outputs and let it refill on its own first.
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Try the reset
Many banks have a reset, often holding the power button for around 10 seconds. The method varies by brand, so check the manual or the maker's support page before trying anything else.
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Warm it up or cool it down
Lithium cells shouldn't charge when very cold or very hot. If it's been in a freezing car or a hot bag, let it reach room temperature first.
03Read the input label before blaming the bank
Sometimes the bank is charging, just slowly enough that it looks broken. The input rating printed on the back tells you how fast it can refill. Multiply volts by amps to get watts.
| Label says | Input power | What it means |
|---|---|---|
| Input: 5V⎓2A | 10W | Slow. A 10,000 mAh bank takes several hours |
| Input: 5V⎓3A / 9V⎓2A (PD) | Up to 18W | Much quicker from a USB-C PD charger |
| Input: PD 20W | 20W | Fast refill; needs a 20W+ USB-C PD charger to reach it |
| Input: PD 30W or more | 30W+ | Big banks; needs a matching charger and a good USB-C cable |
Refill time ≈ (mAh × 3.7 ÷ 1,000) ÷ input watts × 1.2Example: 10,000 mAh is about 37 Wh. At 10W, that's roughly 4 to 5 hours. At 20W, closer to 2 to 2.5 hours.
The 1.2 accounts for energy lost as heat during charging; real times vary with temperature and how the bank tapers at the end. For the mAh and Wh maths in more depth, see mAh vs Wh.
04Charges, but empties too fast
A bank that fills up but gives you far fewer phone charges than it used to has aged cells. Lithium batteries lose capacity with use and time, faster if they're stored full and hot or left empty for months. No reset brings that capacity back.
Keep in mind that even a new bank never delivers its full printed mAh to your phone. Voltage conversion and heat use some of it up. If a 10,000 mAh bank gives your phone about two charges, that's normal. Our power bank calculator estimates what to expect for your phone.
If a bank will sit in a drawer for weeks, leave it around half charged and top it up every few months. Storing it empty is how banks end up in the deep-sleep state above.
05Repair, replace or recycle?
+Worth trying to save
- Charges with a different cable or charger
- Wakes up after an hour on the charger
- Fine, just slow because of a low input rating
–Time to replace
- Swollen, dented, hot or smelly
- Lights flash an error pattern even after a reset
- Holds less than half its original charges
- Got wet, or the casing is cracked
Most electronics and hardware stores have rechargeable battery drop-off bins, and local recycling centers take lithium batteries. Tape over the ports before you drop it off.
A PD wall charger refills USB-C banks quickly; pair it with a bank sized for how you travel.
If the bank charges fine but won't pass power to your phone, that's a separate problem covered in power bank not charging phone.
Questions people ask
How do I reset a power bank that won't charge?
The most common method is holding the power button for about 10 seconds, but it varies by brand, so check the manual. Leaving a drained bank on a charger for an hour often works too.
Why are my power bank's lights blinking but it won't charge?
Blinking lights can mean it is charging, or that it has detected a fault. If it keeps blinking without the level rising after a couple of hours, try another cable and wall charger. A pattern that continues after a reset usually means the battery or circuit has failed.
Can a completely dead power bank be revived?
Often, yes. Banks that were drained very low go into a protective sleep. Leave it on a wall charger for 30 to 60 minutes; some wake more readily on a basic 5V charger. If nothing happens after a few hours, replace it.
Is it dangerous to charge a swollen power bank?
Yes. Swelling means the lithium cells are damaged and can overheat or catch fire. Stop using it, keep it away from flammable materials and take it to a battery recycling drop-off.
Why does my power bank take so long to charge?
Its input may be only 10W, or the charger or cable is limiting it. Check the input rating on the label. A bank with a USB-C PD input refills much faster from a 20W or higher USB-C PD charger.