Why did my battery get worse straight after a software update?
Most of it is the reindexing and re-optimising a major update triggers, which settles within a few days. What remains after a week is a real change, and there are specific things to check.
- Difficulty
- beginner
- Time
- 20 min
- Read
- 4 min
Short answer
Give it three to five days of normal use before judging. After a major update the phone re-indexes photos and files, re-optimises every app, and re-downloads content in the background, all of which is genuinely heavy. If the drain is still bad after a week, look at the battery usage list for a single app that has gone wrong, then check background refresh, location permissions and whether a new feature was switched on by default.
This complaint is extremely common and it has two genuinely different causes that need separating: the temporary work an update creates, and a real regression. Judging on day one guarantees you diagnose the first as the second, and the standard advice to reset everything is nearly always premature.
Step by step
- Wait, and use the phone normally.After a major version update the phone rebuilds search indexes, re-analyses the photo library, recompiles or re-optimises installed apps, and often re-downloads app content. On a phone with a large photo library this can run intermittently for several days, and it is worst when the phone is idle and charging — which is exactly when people notice it.
- Check the battery usage list after a few days, not before.In the battery section of settings, both platforms break down consumption by app over the last day or so and separate screen-on from background use. You are looking for one app with an implausible share — not the messaging app you used all afternoon, but something in the background you barely opened.
- Deal with the offending app specifically.Force-stop it, then check for an update for it — a badly behaved app after an OS update is usually fixed by the developer within a fortnight. If there is no update, restrict its background activity or uninstall it and see whether the drain stops. That is the cleanest possible test.
- Check what the update turned on.Major updates introduce features and frequently enable them by default: new always-on display behaviour, higher refresh rates, additional location or health tracking, background AI or photo analysis. Read the release notes, then look through the display and privacy sections for anything new that is now on.
- Check the screen settings.Screen is almost always the largest single consumer. An update that raised the default brightness, enabled a higher refresh rate, lengthened the screen timeout or turned on an always-on display will show up as a real, permanent increase in drain that has nothing to do with a bug.
- Separate this from battery age.People update and immediately look at battery health for the first time in a year. If the figure is low, the update did not cause that — you have simply noticed a decline that happened gradually. Check the health figure and how the phone behaves in the cold before blaming software.
- Restart properly, once.A full restart after the update settles clears stuck background processes. Do it once, after the indexing has finished, rather than repeatedly during it — restarting mid-index makes the phone start parts of the work again.
- Only then consider a settings reset.Resetting all settings — which keeps your data but returns every toggle to default — sometimes clears a genuinely stuck configuration after an update. It is disruptive enough that it should come after everything above, not before.
If it doesn't work
Phone is warm and draining even when idle
Cause: Background indexing after the update, or one app in a loop — Fix: If it is within a few days of the update and the phone is otherwise fine, wait. If it persists, check the battery list for the culprit and force-stop it. A phone that is warm with no app accounting for it is usually still indexing.
Battery percentage jumps or drops suddenly
Cause: The charge-level estimate has lost its calibration after the update — Fix: Run the phone down until it shuts off, then charge uninterrupted to full and leave it a further hour. This is one of the very few situations where a full discharge cycle genuinely helps, because it re-establishes the reference points the estimate uses.
Drain started after an update but the battery list shows nothing unusual
Cause: System-level activity, or a setting changed by the update — Fix: Look at the screen-on time against the drain rather than the app breakdown. If screen time is similar and drain is higher, look at display settings and background refresh. If screen time is higher, the phone has become more interesting to you and the battery is behaving normally.
Only happens away from home
Cause: A weak mobile signal after a network setting changed in the update — Fix: A phone hunting for signal is one of the heaviest drains there is. Check whether the update altered the preferred network mode, and consider whether wi-fi calling would let it stop hunting indoors.
Questions people ask
Can I go back to the previous version?
Practically, no. Both platforms stop signing older versions shortly after release, and downgrading is unsupported, risky and usually erases the phone. Plan on waiting for the next patch instead.
Should I have waited before updating?
For a major yearly version, delaying a few weeks is reasonable and lets the worst problems get patched. For a security update, no — install it. The two are different in kind.
Do updates deliberately slow old phones to sell new ones?
There is no evidence of that. What is real and documented is that a phone with a badly degraded battery may have its peak performance limited to prevent unexpected shutdowns, which is disclosed in settings and is reversed by replacing the battery.
How long is too long to wait?
A week of normal use. If a major update has not settled by then, treat it as a real change and start the diagnosis above rather than continuing to wait.