If your iPhone seems to lose battery unusually quickly in places with weak mobile coverage, the signal itself may be part of the problem.
When reception is poor, iPhone has to work harder to maintain a connection with the network. Apple notes that both Wi-Fi and mobile connections use less energy when signal strength is good.
This is why battery drain can feel worse on long train journeys, in rural areas, inside large buildings or anywhere your phone repeatedly moves between weak and stronger coverage.
If you know you will be somewhere with no useful signal for a while, Airplane Mode can reduce unnecessary power use. You can still turn Wi-Fi back on separately if a reliable wireless network is available.
On 5G-capable iPhones, 5G Auto can also help by allowing the phone to switch to LTE when faster 5G speeds are not adding much benefit.
The Battery section in Settings can help confirm whether poor coverage is part of the pattern, especially if the drain happens only in certain locations or on particular journeys.
So if your battery behaves normally at home but drops much faster when travelling, the mobile signal is worth considering before blaming the battery itself.
