Does eSIM Drain Your Battery Faster? Separating Fact From Myth

The short answer

Does eSIM drain battery faster than a physical SIM? No. The eSIM is a tiny chip that stores your network profile. It uses about as much power as a plastic SIM card, which is almost none.

What does drain your battery is the radio that connects to the network. Weak signal, a second line hunting for service while roaming, and 5G at low speeds all cost far more power. Those happen with physical SIMs too. Travelers just notice them more, because they often switch to an eSIM on the same trip.

Why people blame the eSIM

Here’s the pattern we see in support chats all the time. Someone installs a travel eSIM, lands in a new country, and watches their battery fall faster than usual. The eSIM is the new thing, so it gets the blame.

But a lot else changed on that same day. The phone is on an unfamiliar network. Signal is weaker inside old buildings and on trains. The home SIM may still be switched on, searching for a partner network. You’re also using maps, the camera and translation apps far more than at home.

The eSIM is just the most visible change. It’s rarely the cause.

What an eSIM actually is

A physical SIM and an eSIM do the same job. Both hold the credentials that tell a network who you are. The difference is that an eSIM’s chip is soldered into the phone and can be rewritten, so you download a profile instead of inserting a card.

Neither one sends or receives signals. That’s the modem’s job, and your phone uses the same modem whichever SIM type you choose. So the SIM format alone can’t change how hard the radio works. For a fuller comparison, see our physical SIM vs eSIM guide.

eSIM battery myths vs facts

Myth	Fact
eSIMs use more power than physical SIMs	Both are low-power chips that store credentials. The radio uses the power.
Storing several eSIMs drains your battery	Stored but inactive profiles don’t connect to any network. Only active lines matter.
Dual SIM always halves battery life	Most phones run Dual SIM Dual Standby, sharing one radio. The real cost is a second line searching for signal.
A travel eSIM is weaker than a local SIM	Signal depends on the network you connect to, not the SIM format.
5G always drains more battery	5G is less efficient at low speeds but can be more efficient for big downloads.

What really drains your battery abroad

Here are the real causes, roughly from biggest to smallest. I’ve attached the research to each one.

1. Weak signal

This is the big one. When signal is weak, your phone boosts its transmit power and retries more often. A study of 3,785 smartphones across 145 countries found that downloading the same file over 3G used about 52% more energy in weak signal. On Wi-Fi, energy rose by as much as 810%. The same study found phones spent almost half their time in poor 3G signal.

Source: Ding et al., ACM SIGMETRICS 2013.

2. A second line hunting for signal

If your home SIM stays on while you travel, it may keep scanning for partner networks it’s allowed to use. That scanning costs power, especially in places where it can’t find a good match. It’s the most common battery problem we see from travelers using dual SIM.

The fix is simple. Turn off the home line if you don’t need calls or texts. If you do need it, at least turn off its data roaming. Our should data roaming be on or off guide covers the settings.

3. 5G at low speeds

5G isn’t always the battery villain, but timing matters. Researchers at SIGCOMM 2021 found 5G was up to 79% less energy-efficient than 4G at low speeds. At high speeds, 5G could be up to five times more efficient. Ookla’s 2023 data showed 5G using 6% to 11% more battery than 4G.

Most travel use is low-speed: maps, messages and browsing. If your battery matters more than speed, switching to 4G or LTE can help. Read why your 5G phone is showing 4G to understand what your phone is choosing.

Sources: Narayanan et al., SIGCOMM 2021 and TechRadar on Ookla’s data.

4. Switching between networks

Some travel eSIMs connect to more than one local network. That’s good for coverage. But if two networks are both weak, your phone may hop between them, and each switch costs a little power. Our guide on single-network vs multi-network eSIMs explains the trade-off.

5. Travel habits

Navigation, photos, video uploads and screen brightness outdoors all add up. A day of sightseeing can use more battery than three days at your desk. That’s not the eSIM. It’s the trip.

Does dual SIM drain your battery?

A little, but less than people think. iPhones run two lines in Dual SIM Dual Standby mode. Apple says your iPhone can use one cellular data network at a time, so both lines share the same radio.

The extra cost comes from the second line staying registered and checking for calls. On strong home networks, that cost is small. A three-month test by Data Overhaulers on a Google Pixel found no major difference in battery use between one and two active lines.

Abroad, things change. A home SIM roaming on a weak partner network can search constantly. That’s why the same dual SIM setup feels fine at home and drains quickly overseas. If you’re unsure how your phone handles two lines, read can I use an eSIM and a regular SIM at the same time.

Seven ways to save battery with a travel eSIM

1. Turn off your home line if you don’t need calls or texts. This removes the biggest roaming drain.
2. Turn off data roaming on your home SIM if you keep it on for texts.
3. Choose 4G or LTE when you don’t need top speeds.
4. Use Low Power Mode or Battery Saver on long sightseeing days.
5. Download offline maps on hotel Wi-Fi before you head out.
6. Switch on airplane mode on flights, trains through tunnels and anywhere with no signal.
7. Install your eSIM before you fly. Setting it up on home Wi-Fi avoids a long search for signal on arrival.

BazTel plans start on first connection abroad, not at install, so installing early costs you nothing. You can check your phone’s eSIM compatibility first.

When your battery drain might not be the network

Sometimes the cause is something else entirely. Check your phone’s battery settings if drain started suddenly. On iPhone, go to Settings and then Battery. On Android, open Settings, then Battery, then Battery usage.

Look for an app using far more than usual. Background sync after a software update is a common culprit. If one app stands out, close it or restrict its background activity. Samsung users can follow our guide on stopping background apps eating your travel eSIM data, which helps battery too.

Does eSIM drain battery: FAQs

Does an eSIM drain battery faster than a physical SIM?

No. Both store your network credentials and use almost no power. Battery drain comes from the radio, signal strength and how you use your phone.

Do two eSIMs drain your battery?

Only if both lines are active. Stored eSIM profiles that are switched off don’t connect to any network. Two active lines can add a small cost, which grows when one line is roaming on weak signal.

Why does my battery drain faster when I travel?

Mostly weak signal, a home SIM searching for networks, heavy use of maps and the camera, and brighter screens outdoors. The SIM format plays almost no part.

Should I turn off my physical SIM when using a travel eSIM?

If you don’t need calls or texts on your home number, yes. It removes a second line searching for signal. If you need texts for bank codes, keep it on and turn off its data roaming.

Does 5G drain battery faster on an eSIM?

5G can drain more battery at low speeds, whichever SIM type you use. Switching to 4G or LTE saves power when you only need maps and messaging.

The bottom line

The eSIM itself is innocent. Battery drain abroad comes from weak signal, a home line searching for service and the way travelers use their phones. Fix those, and a travel eSIM can actually help your battery by giving you one strong local connection.

If you’re heading off soon, a BazTel eSIM from US$1 gives you that local data line without the battery-sapping roaming hunt. For more on how eSIMs perform abroad, read our guide to travel eSIM reliability and speed.