You plug them in, no light, nothing. Before assuming the battery is dead, work through the chain, because the two most common causes cost nothing to fix and the second one requires only patience.
The short answer
Leave them charging for at least four hours before deciding anything, since a deeply discharged battery shows no sign of life for a long time. Clean the charging port or the contacts, which collect lint and skin oil. And try a different cable and a proper wall charger rather than a laptop port, which often supplies far less than it should.
Deep discharge takes longer than you think
A lithium battery that has been flat for weeks drops below the voltage its protection circuit will accept a normal charge at. The charger then trickles a very small current in until the voltage recovers, and only then begins charging properly. During that phase there may be no indicator light at all.
On headphones with a large battery that phase can take hours. People give up after twenty minutes, conclude the battery is dead, and throw away a working pair. Plug them in and leave them alone for an afternoon before concluding anything.
Use a wall charger rather than a computer port
Laptop and monitor USB ports often supply far less current than expected, and some supply nothing when the laptop is asleep. Use a proper mains adapter.
Leave them for four hours untouched
Do not press buttons, do not unplug and replug to check. Each interruption can restart the pre-charge cycle. Plug in and walk away.
Try a different cable
Cables fail internally and the one that lives in a bag with headphones has usually had a hard life. Borrow one you know works.
Inspect the port or contacts with a torch
On over-ear headphones, look into the charging port for lint. On earbuds, look at the metal pads on the buds and the pins in the case. Corrosion shows as green or white residue.
Clean carefully
A wooden toothpick for a port, working gently around the edges. A cotton bud barely dampened with isopropyl alcohol for contacts. Let everything dry fully before charging.
Check the case charges, for earbuds
The case is a separate battery. If the case is flat, the buds cannot charge from it no matter how healthy they are. Charge the case first and check its own indicator.
Look for a reset
Many headphones have a reset, often a button held for ten to twenty seconds or a pinhole. A locked-up controller refuses to charge until reset.
Feel for warmth after twenty minutes
Slight warmth near the port means current is flowing and it is working slowly. Completely cold with a known-good cable and charger means nothing is getting in.
Never charge headphones that are damp. Sweat and rain get into the port and the charging contacts, and water plus current is exactly how a recoverable device becomes a corroded one. After exercise or rain, leave them out in open air for several hours before charging.
Earbuds specifically
With earbuds there are three things that can fail rather than one: the left bud, the right bud and the case. Work out which:
- Case will not charge from the wall. Cable, port or case battery.
- Case charges, one bud does not. That bud’s contacts, almost always. Clean them.
- Case charges, neither bud does. The case pins, or the case has failed to deliver power.
- Both charge but run out quickly. Battery wear rather than a charging fault.
Dirty contacts are the overwhelming favourite for a single bud not charging, and cleaning them with isopropyl alcohol on a cotton bud fixes it most of the time.
Clean the charging contacts monthly whether or not anything is wrong. Earwax and skin oil build up on the pads and in the case pins, and the decline is gradual enough that you notice only when a bud stops charging entirely. Thirty seconds a month prevents the whole problem.
When the battery has failed
Signs: it charges to full and empties within an hour, it gets hot while charging, the case has visibly swollen, or it will not hold any charge at all after a full night on a known-good charger. A swollen case or earbud is a safety matter and should be recycled properly rather than used.
Whether replacement is worth it depends on the headphones. Over-ear models sometimes use a standard cell that a repairer can swap. Earbuds are glued and not economically repairable, though single replacement buds are often sold as spare parts at a fraction of the price of a new set.
How long should I leave dead headphones charging?
At least four hours, and overnight is better. Deeply discharged batteries show no indicator activity for a long time, and impatience is the most common misdiagnosis.
Why does only one earbud charge?
Almost always dirty contacts on that bud or its pins in the case. Clean both with isopropyl alcohol on a cotton bud and let them dry fully.
Can I charge from a laptop USB port?
Slowly at best, and some ports supply nothing when the laptop sleeps. Use a proper wall charger, especially when reviving something flat.
Is a swollen charging case dangerous?
Yes. Stop using it, do not charge it, do not press on it, and take it to a battery recycling point rather than putting it in general waste.
How do I stop this happening again?
Do not store them flat for months; charge to about half before putting them away. Clean the contacts monthly, and never charge them while damp.
The bottom line
Plug them into a proper wall charger and leave them alone for four hours, because deep discharge recovery is slow and giving up early is the most common mistake. Then clean the port or the contacts, which is the next most likely cause and costs nothing. For earbuds, establish whether it is a bud or the case before concluding anything.
