Emma updated her phone on a Sunday night in Manchester, plugged it in, and went to bed feeling organised. By Monday lunchtime, on the train to Leeds, her battery was already below twenty percent, even though she had barely used it. She had not changed her habits. She had not installed a new game. The only change was the update. If that story sounds familiar, you are asking the same question as thousands of other phone owners right now: why phone battery drains fast after update, and what can you actually do about it?
The short answer is reassuring. In most cases, the battery itself is fine. The update has simply set off a busy period behind the scenes, changed a few settings without telling you, and given some apps a reason to work harder than usual. Once you know which of those three causes is at work on your phone, the fix is usually simple, and it rarely means buying a new phone or wiping everything and starting again.
This guide explains the real reasons in plain language, shows you how to check your own phone in a few minutes, and gives you a fix order that works for both iPhone and Android. It is written for everyday use in the UK, from commuting and working from home to long evenings of video calls, maps, and streaming.
Why Phone Battery Drains Fast After Update in the First Few Days
A major software update is not just a fresh coat of paint. It changes how the phone organises photos, messages, files, and search results. After the update finishes, the phone still has a lot of quiet work to complete. It rebuilds search indexes so you can find a photo or a message quickly. It checks every app against the new system. It downloads extra files for new features. It syncs photos and messages again. All of that work uses the processor, the storage, and the network, and all of it uses power.
That is why the first day or two often feel the worst. The phone may feel warm even when the screen is off. The battery percentage may fall faster during the night than it used to. Apps may take a second longer to open while the system finishes its housekeeping. Apple itself explains that a temporary effect on battery life and warmth is normal right after a major update, while the phone indexes data and files, downloads new assets, and updates apps. For many people, this settling period lasts two to three days. For phones with very large photo libraries, or with a lot of messages and files tied to search and voice features, it can last closer to a week.
The mistake most people make is to panic on day one and change twenty settings at once, or to wipe the phone completely. A calmer approach works better. Give the phone a few nights on charge, connected to wifi, so the background work can finish. Then judge the battery against how it behaved before the update, not against how it behaved on the first morning after it.
The settling period is real, but it should end
Think of the settling period as moving house. The boxes are in, but nothing is in the right room yet. For a few days, you spend extra energy finding things. Then, once everything has a place, life returns to normal. Your phone works the same way. If the drain is still just as bad after a full week of normal use, with the phone charged overnight on wifi, then something else is going on. That is the point to work through the checks below, one at a time, so you can see which change actually helps.
Settings that quietly change during an update
Updates can reset preferences you set months ago. A location setting that used to allow access only while you were using an app may switch back to always. A screen setting may return to full brightness or to a faster refresh rate. A voice feature may become more sensitive. A wifi setting may start using mobile data at the same time as wifi, to keep the connection steady, which means two radios are working at once instead of one resting.
None of these changes is dramatic on its own. Together, they add up. A social app checking your location in the background, a bright screen staying on a little longer, and a phone holding on to a weak mobile signal can easily turn a full day of battery into half a day. The good news is that each of these settings takes less than a minute to check, and putting them back to how you had them often restores most of the lost battery life.
Apps that no longer behave on the new system
Apps are built for a particular version of the operating system. When that system changes, an older version of an app can misbehave. It may keep waking the phone to check for messages. It may fail to pause properly when you switch away from it. It may keep asking for location, even when you are not using it. Social apps, video apps, messaging apps, and games are the usual suspects, because they refresh often, play video automatically, and send a lot of notifications.
This is also why updating your apps right after a system update matters so much. Developers release fixes for the new system in the days after it arrives. A single out of date app can undo all your other good habits, so it is worth checking for app updates before you blame the battery or the phone itself.
How to Tell Normal Drain From a Real Problem
Before you change anything, spend two minutes looking at the evidence on your own phone. Guessing wastes time, and it often leads to changing settings that were never the problem. Your phone already keeps a clear record of what used power, and reading it turns a vague worry into a short list of suspects.
On an iPhone, open Settings, then Battery. Look for the battery usage list for the last 24 hours and the last 10 days. Tap any app to see how much time it spent on screen and how much time it spent in the background. Pay special attention to any app with a large amount of background time, and to any note about an ongoing update. If you see a note saying an update is still in progress, the settling period has not finished yet, and patience is still the right first step.
On Android, open Settings, then Battery, then Battery usage. The layout varies a little between Samsung, Google Pixel, and other makers, but the idea is the same. Look for apps with high background use, and for system items such as mobile network, wifi, and screen that are using far more power than usual. If one app stands out far above the rest, you have found your starting point. If everything looks fairly even, but the total drain is still high, the cause is more likely to be settings, signal, or screen brightness than a single rogue app.
Also check battery health while you are there. On an iPhone, Settings, then Battery, then Battery Health and Charging shows maximum capacity as a percentage. A phone at 88 percent capacity will not last as long as it did when it was new, but it should still get through a normal day with sensible settings. If capacity is below 80 percent, or if the phone shuts down unexpectedly, the battery itself may need attention, and no setting will fully fix that. On many Android phones, battery health appears in Settings, then Battery, or in a diagnostics tool from the maker, such as Samsung Members. If your phone does not show it, a visit to a repair shop can confirm it in minutes.
Three simple questions will guide everything that follows. Is the drain worst in the first few days after the update, or is it still bad a week later? Is one app clearly responsible, or is the drain spread across the whole system? Does the phone also feel hot, lose signal often, or struggle in one particular place, such as a basement flat or a long train journey? Your answers point to the right fix, and they stop you from wasting an evening on the wrong one.
The Simple Fix Order That Works for Most People
Work through these steps in order, and check the battery after each one. The order matters. It starts with the free, harmless steps that help most people, and it leaves the drastic steps until last. Do not skip ahead to a full reset. Most phones recover long before that point.
Step one: give the update time to finish
Leave the phone on charge overnight, connected to wifi, for two or three nights after a major update. Keep it in a cool place, out of direct sunlight, and not under a pillow. Do not keep force closing apps from the recent apps screen. Paused apps use very little power, and forcing them closed means the phone has to load them from scratch next time, which uses more power, not less. After a few nights, check the battery usage screen again. If the ongoing update note has gone, and the drain has eased, you may already be done.
Step two: restart the phone and update every app
Restart the phone once. A restart clears stuck processes that can keep running quietly after an update. Then open the App Store on iPhone, or Google Play on Android, and install every available app update. This one step fixes a surprising number of post update problems, because it brings older apps up to date with the new system. While you are there, delete any app you have not opened in months. Every app you remove is one less app that can wake the phone, ask for location, or send notifications.
Step three: tame background activity and location
Open the battery usage list again and look at the top few apps. For any app that does not need to work in the background, turn off background refresh. On iPhone, this is in Settings, then General, then Background App Refresh. You can turn it off for individual apps, keeping it on only for messaging, email, and maps. On Android, open Settings, then Apps, choose the app, then Battery, and set it to restricted or optimised background use.
Next, check location. Many apps ask for location all the time when they only need it while you are using them. On iPhone, go to Settings, then Privacy and Security, then Location Services, and change Always to While Using the App for social apps, shopping apps, and games. On Android, go to Settings, then Location, then App permissions, and make the same change. Keep Always only for apps that genuinely need it, such as a family safety app or a running tracker you use every day. This single change often makes the biggest difference of all.
Step four: calm the screen and the radios
The screen is usually the largest single user of power, so small changes here pay off quickly. Turn on automatic brightness, so the screen dims indoors and brightens only when you step outside. Shorten the auto lock time to 30 seconds or one minute, so the screen does not stay lit on a table while you make tea. If your phone has an always on display, try turning it off for a few days and see how much battery you save. If you have a phone with a very fast refresh rate, switching it from the fastest setting to automatic or standard can also help, with very little visible difference in everyday use.
Signal matters just as much. A phone in a weak signal area works much harder to stay connected, and it heats up as it searches for a signal. When you are at home or at work, stay on wifi, because wifi uses less power than mobile data. When you are somewhere with no coverage at all, such as a rural walk or a basement car park, flight mode saves a lot of power. On a train with patchy coverage, downloading music, podcasts, or maps before you travel means the phone is not constantly searching for a signal to stream them.
- Restart the phone once, then update every app before changing anything else.
- Turn off background refresh for apps that do not need to update while you are not using them.
- Change location access from Always to While Using the App wherever possible.
- Use automatic brightness, a short auto lock time, and wifi whenever it is available.
- Check battery usage again after a day, and only then move to the next step.
iPhone Fixes That Matter Most in the UK
iPhone owners in the UK have one extra setting worth checking after a recent update. A wifi feature that keeps mobile data active alongside wifi, to improve reliability when wifi is slow, can leave both radios working at once. Some users who updated recently found that turning this feature off restored several hours of battery life, especially at home where wifi was already weak in a back bedroom or a garden room. On iPhone, open Settings, then wifi, and look for the connectivity setting for your network. If you do not need the extra help, turn it off for your home network and your work network, and keep mobile data for times when you are truly away from wifi.
Also check Low Power Mode as a short term tool, not a permanent fix. Low Power Mode reduces mail fetch, pauses some visual effects, and limits background activity, and it can easily add several hours when you need them, such as on a long day out in London or a day of back to back meetings. Turn it on from Settings, then Battery, or from Control Centre, and turn it off again when you are near a charger. If Low Power Mode makes a dramatic difference, it confirms that background activity, rather than the battery itself, was the main problem.
Finally, check Siri and search settings if your phone is still settling. After a major update, the phone spends extra time learning how you search for photos, messages, and apps. You do not need to turn these features off permanently, but if battery life is still poor after a week, turning off suggestions for a few apps you rarely use can reduce background work while the system finishes catching up.
Android Fixes That Matter Most
Android phones vary more than iPhones, but the principles are the same, and Samsung and Pixel phones both have excellent built in tools. On a Samsung phone, open Settings, then Battery and device care, then Optimise now. This closes background apps, clears memory, and checks for obvious problems in one tap. You can also set it to optimise automatically overnight. On a Pixel phone, Adaptive Battery learns which apps you use most and limits the rest, so leave it turned on and give it a few days to learn your routine after an update.
Android also lets you be more specific about mobile data. If 5G coverage is patchy where you live or work, the phone can waste a lot of power switching between 5G and 4G. Setting your preferred network type to 4G or LTE in Settings, then Connections or Network, then Mobile networks, often gives a steadier connection and a noticeable battery saving, with no real loss for browsing, maps, messaging, or streaming music. Save 5G for times when you genuinely need very fast downloads.
Be wary of battery saver apps from the app store. The built in Battery Saver on Android, and Low Power Mode on iPhone, already do everything useful, and they do it safely. Third party battery apps often run constantly themselves, show adverts, and ask for permissions they do not need. If an app promises to double your battery life or to cool your phone with one tap, it is almost certainly making the problem worse, not better.
Habits That Protect Battery Health for Months
Once the post update drain is fixed, a few gentle habits will keep your battery healthier for much longer, and they cost nothing. Avoid leaving the phone in a hot car, on a sunny windowsill, or on top of a radiator. Heat is the fastest way to age a battery. Charge with a decent cable and charger, and avoid very cheap chargers that overheat. You do not need to charge to exactly 100 percent every time, and you do not need to let the phone run flat before charging. Modern phones manage charging well on their own, especially with optimised charging turned on, which holds the charge at around 80 percent overnight and finishes just before you wake up.
Small daily choices add up too. Downloading a playlist or a podcast on wifi before a journey beats streaming it over a weak mobile signal. Using dark mode on a phone with an OLED screen saves power, because dark pixels are switched off, while on an older LCD screen the saving is small. Keeping the phone out of a thick metal case while charging helps it stay cool. None of these habits requires effort, but together they mean fewer charges, less heat, and a battery that stays strong for an extra year or more.
When a New Battery Makes More Sense Than More Settings
Sometimes, the honest answer is hardware, not software. If your phone is three or four years old, if maximum capacity is well below 80 percent, if the phone shuts down when it still shows 20 percent, or if the back of the phone feels swollen or uneven, no setting will restore it. In that case, a battery replacement is usually far cheaper than a new phone, and it can make an older phone feel new again. In the UK, an official battery replacement through Apple or an authorised service provider often costs around £69 to £99, depending on the model, while a good independent repair shop may charge less. Always ask about the warranty on the new battery, and keep the receipt.
Do not replace the battery on day two after an update, though. Wait until the settling period is over, work through the fix order above, and compare the battery with how it behaved before the update. If it is still far worse after a week, and battery health is low, then a replacement is a sensible investment, not a panic purchase. If battery health is still good, but drain continues, ask a repair shop or the maker support team to check for a software fault or a faulty update, because a further update may already be on its way to fix it.
Conclusion: A Calm Fix Beats a Drastic One
So, why phone battery drains fast after update? Most of the time, the answer is a busy settling period, a few settings that changed without you noticing, and one or two apps working too hard on the new system. That combination feels alarming, especially when a phone that lasted all day suddenly needs a top up by lunchtime, but it is also one of the most fixable phone problems there is.
Start by giving the update a few nights to finish. Restart the phone, update every app, and read your battery usage screen before you change anything else. Tame background refresh and location access, calm the screen, and stay on wifi when you can. Check the UK specific wifi setting on iPhone, and the network and device care tools on Android. Only if the drain is still bad after a full week, and battery health is low, should you think about a new battery.
Emma, on that train to Leeds, did exactly this. She waited three days, updated her apps, changed location access for her social apps, and turned off the extra wifi help on her home network. By the following Monday, her phone was lasting until bedtime again, with charge to spare. Your phone can usually do the same, without a wipe, without a new handset, and without a single drastic step.
Frequently Asked Questions
Is it normal for my phone battery to drain fast after an update?
Yes, for the first few days. The phone rebuilds search indexes, updates apps, and syncs files in the background. If the drain eases within a week, it was normal settling. If it stays just as bad after a week, work through the battery usage checks in this guide.
How long should I wait before worrying about post update battery drain?
Give it at least three days, and ideally a full week, with the phone charged overnight on wifi. Judge the battery after that period, not on the first morning. If an ongoing update note is still showing in battery settings, the phone has not finished yet.
Which app usually drains the battery most after an update?
There is no single culprit for everyone, but social apps, video apps, and messaging apps are the most common, because they refresh often and use location and notifications heavily. Check Settings, then Battery, then Battery usage on your own phone to see your top app.
Should I wipe my phone to fix battery drain after an update?
No, not as a first step, and usually not at all. A wipe deletes everything and takes hours to undo, while most drain is fixed by updating apps, limiting background activity, and fixing location and screen settings. Keep a wipe as a last resort, after a full backup, and only if nothing else helps.
Will a new battery fix drain caused by a software update?
Only if the battery itself is worn. If maximum capacity is still good, a new battery will not fix a settings or app problem. Check battery health first. If capacity is below 80 percent, or the phone shuts down unexpectedly, a replacement is worth considering.
