I have an older iPhone that already needs a battery replacement. When the battery drops below about 20%, plugging it in doesn't seem to start charging unless I restart the phone first. Yesterday I left it connected overnight at 20%, but it still dropped to 18% by morning. What could cause this behavior?
1 Answer
The battery is probably the main culprit here. An iPhone 11 with only 71% maximum capacity has a significantly worn battery, and it may no longer report its charge level or accept power reliably. The charging cable, adapter, or Lightning port could also be contributing, so try another known-good cable and adapter and check the port for debris. However, replacing the battery is the most likely fix. Since restarting temporarily makes charging work, there may also be a software or power-management glitch, but the battery’s condition makes hardware wear the stronger suspect.
It’s an iPhone 11 running iOS 26.6, and Battery Health shows 71% maximum capacity.