A power bank rarely fails all at once — it degrades gradually, and most people keep using one well past when they should.
- It no longer holds a full charge overnight
- It feels warm even when not in use
- Output has dropped well below its rated wattage
- The casing has visibly swollen
Important: A swollen battery casing is a genuine safety hazard, not just a performance issue — stop using it immediately and dispose of it through a battery recycling program rather than regular trash.
Bottom line
Any single sign on this list is worth paying attention to; two or more together is a clear signal to retire the power bank.