No more than a plastic SIM does — but running two lines at once uses a little more than one, and a weak signal uses a great deal more than either
The chip itself is not what costs battery. The radio is, and how hard the radio has to work depends on signal strength rather than on the format of the SIM.
What Actually Drains It Abroad
- A weak signal. A phone hunting for a distant mast transmits at full power, and this is by far the largest effect
- Two lines registered. Keeping the home line active as well as the travel eSIM costs a small amount continuously
- Hotspot. Sharing the connection is one of the most demanding things a phone does
- 5G in patchy coverage, where the phone keeps switching between network types
Making It Last the Day
- Switch off the home line if you do not need calls to your own number
- Turn off 5G where coverage is thin — 4G is steadier and cheaper on battery
- Use flight mode in places with no signal rather than letting the phone search
- Turn the hotspot off when nothing is connected to it
Days of heavy sightseeing drain a phone regardless — maps, camera, screen brightness in sunshine and a full day away from a charger. The eSIM is a small part of that, and a power bank is the real answer.
If the battery is noticeably worse than at home, weak signal is almost always the reason. Flight mode on the train through the mountains will do more for it than any setting
