I already tried restarting my iPhone, checking battery usage, and turning off background refresh, but since iOS 27 it still drops from 100 to 40 by lunch. I use it for my work team, mostly for messages, calendar, and occasional calls, so this was not what I expected.
Is anyone else seeing the same drain, and is this usually an indexing thing after an update, or am I using the wrong term for it?
A phone that runs warm and drains quickly for the first day or two after a major update is different from one that still does it several days later. “Indexing” is basically the right term, though “post-update background processing” is broader. Spotlight, Photos, app updates, and account syncing can all keep working after the installation finishes.
Since yours is used for work, check Settings > Battery > View All Battery Usage and look for heavy background time from your mail, calendar, messaging, VPN, or device-management apps. Turning off Background App Refresh does not necessarily stop push mail, corporate account syncing, VPN activity, or system tasks. Poor cellular coverage can cause a surprisingly large hit too.
Leave it charging on Wi-Fi overnight and give it a couple of full days. If it is still draining hard while mostly idle, especially if it stays warm, involve your IT team before removing any work account or management profile. A stuck Exchange sync or work app may be more likely than ordinary indexing at that point.
Do not factory reset your phone. Make sure that every single piece of software on your App Store is updated. Sometimes work apps do not work correctly after an update so try using Low Power Mode as a temporary fix.
Don’t let “indexing” become the universal excuse for a phone that now needs a lunchtime charger. If the update was several days ago and the drain has not eased, treat it as an actual fault rather than waiting indefinitely for the phone to sort out its feelings.
Check Settings > Battery > Battery Health for maximum capacity or a service warning. A worn battery may have seemed acceptable before the update, then the extra workload exposed how little headroom it had left. Software did not suddenly age the battery, but no amount of disabling widgets and animations will rescue a battery that is already near replacement territory.
For a cleaner test, charge it and leave it in Airplane Mode with the screen off for a while after work. Then repeat with Wi-Fi enabled, followed by your normal cellular, VPN, and work setup. If it barely drops while disconnected but starts falling once the work connection returns, you have something useful to show IT instead of the vague “battery is bad” report. Take screenshots of the battery graph and background activity when it happens.
If it still loses a large chunk while disconnected and untouched, especially while warm, that points more toward the battery or the update installation itself. At that stage I would run Apple’s diagnostics or arrange service before doing a full erase. Randomly toggling another dozen settings is mostly a great way to forget which setting mattered.
Check whether Home & Lock Screen is significantly towards the top of the Battery page. It may seem less obvious than the list of apps, but it’s common for people to miss it. If it’s unusually high, the phone could be waking up for work-related messages, calendar alarms, or similar tasks. The particular app that’s sending the notifications could appear to be relatively harmless, while the bigger battery drain comes from the lock screen itself.
The percentages on this page can be misleading as well. If some app is using 30%, it doesn’t mean that it’s sucked 30 percent of the battery’s power. It only means that it used 30 percent of the energy that the phone had to expend to operate during the day. To get an idea of what’s going on, tap the graph at the place where it reaches its highest point in the morning and compare Screen Active and Screen Idle. The higher the latter is, the more time the phone spent in the process of syncing or connecting to networks. Screen Active is more likely to point to notifications if they cause frequent short-term spikes.
As an experiment, you could try disabling Lock Screen notifications for the most persistent apps for an hour or so, leaving the phone on but with the display turned off. It should still be able to access work apps, but its ability to do so would be limited to whatever the default behavior was before you began your test. This way, you can see whether the line on the graph changed without having to turn off all the unnecessary services and make the device unusable for work.
Low Power Mode, as @brightrouter5954prim suggested, can get you through the day, but I would not use it while trying to identify the cause. It changes several behaviors at once, so an improvement does not tell you whether the culprit was mail fetching, display activity, background processing, or something else. Use it when you need the runtime, then turn it off for a controlled test.
If Home & Lock Screen is normal, and one of the work apps you use is persistently performing lots of background activity, you will want to check that app’s notification and sync settings before removing the entire work account. Some apps automatically revert to more aggressive options following a significant update or their own update. For instance, a calendar app may begin to refresh many shared calendars, or a chat app may resume notifications for channels you had silenced.
Install any available follow-up system update you are made aware of so long as you have confirmed it is acceptable to your employer, as early maintenance releases are likely to resolve power and compatibility drain issues. If the drain persists, it would help if you sent IT screenshots of the chosen time frame, Screen Active/Idle, and what activity breakdown you see. This way, they have a concrete idea to work with without needing to wipe your phone or remove you from management entirely.
The number you’re watching might be lying to you for a bit. After a big version jump the battery gauge often needs to recalibrate, and during that window the percentage can read low or drop in chunks that don’t match real usage. So a 100 to 40 by lunch reading in the first several days isn’t automatically the same crisis it would be three weeks later. Worth knowing before you tear through every setting chasing a number that hasn’t settled yet.
That said, I’m with @virtualnode4011hq on not letting ‘indexing’ become a permanent alibi. The airplane mode test is the right instinct, but I’d add a wrinkle: run it a few days apart, not back to back, because if the gauge is still recalibrating your first idle test can look worse than the phone actually is. Same test later gives you a cleaner baseline.
Where I’d push back a little is the rush to Battery Health as the answer. A worn cell absolutely shows up harder under a heavier OS, no argument there, but if capacity reads high and there’s no service warning, don’t fixate on it. Work profiles are the usual quiet offender. A managed device can get handed new configuration after an update, and things like more frequent location checks or a tightened compliance poll will grind at the battery without any single app looking guilty.
One thing people forget: heat and charging habits. If it’s living in a thick case on a wireless pad all afternoon at your desk, it’s cooking gently the whole time, and that both drains faster and ages the cell quicker than the update ever could.
My honest take, keep it simple. Give it a few days to settle, take one clean idle screenshot now and one after the next maintenance release, and if the slope is still ugly with everything disconnected, that’s your evidence for service or IT. Everything in between is mostly guesswork.
A comparison to airplane mode is too unrealistic of a scenario for a work phone. It demonstrates that the radios are indeed a factor, but doesn’t narrow down what part of your real-world usage is bleeding through. Compare the same paired application use on-home and on the network.
Should the drain be more severe at the office, it’s either poor coverage/Wi-Fi handoffs, the VPN, or repeated corporate logins. If it’s both about the same, the update itself or an incompatible application is the culprit.