Charging Stopped at 80%
Anker Power Bank
Severity: MinorWhat Does This Error Mean?
It is normal for Anker power banks to charge quickly to 80% and then slow down significantly — this is trickle charging to protect the lithium battery. The last 20% can take as long as the first 80%. Leave it plugged in and it will reach 100%.
Affected Models
- Anker PowerCore 10000
- Anker PowerCore 20000
- Anker PowerCore III
- Anker 737 (PowerCore 24K)
- Most Anker power banks
Common Causes
- Normal trickle charging behaviour — lithium batteries always slow down in the top 20%
- Charger wattage insufficient for the bank's capacity — slow top-up phase
- Charge optimisation feature (Anker's Smart Charge) limiting charge to 80% intentionally
- Power bank battery degraded and only holding 80% of original capacity
How to Fix It
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Leave it plugged in — the last 20% is just slower.
Lithium battery charging always slows above 80%. This is the trickle (CV) phase where the charger reduces current to safely fill the final cells. On a 20000mAh bank, this slow phase can take 1–2 hours more.
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Check that the charger meets the recommended wattage.
Larger Anker power banks (20000mAh+) require a higher-wattage charger (18W or more) to charge at full speed. Using a 5W phone charger will cause the top-up phase to take many additional hours.
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Check the Anker app if your model supports it.
Some Anker smart power banks have a battery protection mode in the Anker app that limits charging to 80% for long-term storage. Open the Anker app → your device → check for a charging limit or battery optimisation setting.
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Test the actual capacity.
Fully charge the power bank (all four LEDs solid), then drain it completely into a phone to measure how many charges it provides. If it provides significantly less than the rated capacity, the cells are degraded.
When to Call a Professional
If the power bank consistently stops at 80% and will not progress further even after several hours, the battery cells may have degraded. Contact Anker support for a warranty assessment.
Frequently Asked Questions
Anker power bank takes 12 hours to fully charge — is that normal?
A 20000mAh bank takes 8–10 hours on a standard 10W charger, and 4–5 hours on an 18W charger. 12 hours is slow — try a higher wattage USB-C PD charger and use the correct input port.
My Anker power bank used to charge to 100% but now always stops at 80% — why?
If this changed suddenly, a firmware update may have enabled battery optimisation mode. Check the Anker app for a charging limit setting. If no app is available and no settings changed, the battery has degraded and cannot fill completely.