iPhone Battery Draining Fast After the iOS 27 Update? Here's How I Fixed Mine

Two days after I updated my iPhone to iOS 27, I noticed something annoying. I unplugged my phone at 8 in the morning, and by lunchtime — with barely any use — it was already sitting at 42%. I hadn't changed how I use my phone. Same apps, same routine. The only thing that changed was the update.

If that sounds familiar, you're not the only one. Every big iOS update seems to come with a wave of "my battery is dying" complaints, and honestly, most of the time it's not a broken battery. It's a handful of settings that quietly reset, turn themselves back on, or start working overtime after an update.

I spent an evening going through my phone setting by setting. Below is everything that actually helped — the 9 fixes from my video, written out in full, plus 8 more tips I didn't have room for on camera. Work through them in order. You probably won't need all of them, but by fix number nine my phone was back to lasting the whole day.

First, Give It a Day (Seriously)

Before you change anything: if you updated in the last 24–48 hours, some drain is normal. After a major update, your iPhone re-indexes photos, files, and messages in the background, and that eats battery for a day or two. Plug it in overnight, keep it on Wi-Fi, and let it finish.

Still draining after two days? Then it's settings. Let's fix it.

Fix 1: Turn On Connectivity Assist

Go to Settings → Wi-Fi, scroll to the bottom, and turn on Connectivity Assist.

When your Wi-Fi connection is weak, your iPhone normally clings to it and keeps struggling — which burns battery. Connectivity Assist lets the phone quietly use cellular data to help out when Wi-Fi is poor, instead of fighting a bad connection. Counterintuitive, but a phone that stops struggling with weak signal is a phone that uses less power.

Fix 2: Turn Off Bluetooth When You're Not Using It

Settings → Bluetooth — if you don't have earbuds, a watch, or your car connected right now, switch it off.

Bluetooth left on all day spends its time scanning for devices to connect to. It's a small drain on its own, but it's one of those "death by a thousand cuts" things. Off when you don't need it. Simple.

Fix 3: Turn Off Background App Refresh

This one is a biggie. Go to Settings → General → Background App Refresh, tap it at the top, and choose Off.

By default, dozens of apps refresh themselves in the background — checking for new posts, new messages, new prices, new everything — whether you're looking at them or not. Every one of those wake-ups costs battery. Turning it off globally doesn't break anything important; your apps just update when you actually open them, like they did in the old days. We survived then. We'll survive now.

Fix 4: Turn Off Personal Hotspot

Settings → Personal Hotspot — make sure "Allow Others to Join" is off unless you're actively sharing your connection.

People forget this one constantly. You turn the hotspot on once for a friend or a laptop, forget about it, and your phone spends the rest of the week broadcasting a network nobody's using. Check it now. I'll wait.

Fix 5: Stop Mail From Checking All Day

This was the worst offender on my phone, and I had no idea.

Go to Settings → Apps → Mail → Mail Accounts → Fetch New Data. If Push is on at the top, turn it off. Then tap each email account and set it to Manual, and set the Fetch schedule at the bottom to Manually as well.

With Push on, your phone maintains a constant connection so emails arrive the second they're sent. Sounds great — costs you battery all day long. On Manual, your email simply refreshes when you open the Mail app. Unless you're a day trader or a surgeon, your inbox can wait thirty seconds.

Fix 6: Turn On Auto-Brightness

Settings → Accessibility → Display & Text Size — scroll all the way down and make sure Auto-Brightness is on.

Your screen is the single biggest battery user on the phone, full stop. If Auto-Brightness got switched off at some point, your screen can sit at near-max brightness in a dim room for no reason at all. Let the phone manage it. It genuinely is better at this than we are.

Fix 7: Find the App That's Eating Your Battery

Go to Settings → Battery and scroll down to the usage list. This page doesn't lie.

On mine, Home & Lock Screen was weirdly high (more on that below), and one social app I'd barely opened was somehow responsible for a huge chunk of background activity. If an app you rarely use is near the top of the list, that's your culprit. Swipe it closed properly, and if it keeps showing up day after day, delete and reinstall it — a fresh install fixes a surprising number of "stuck" apps.

Fix 8: Turn On Adaptive Power

Back in Settings → Battery, tap Power Mode and turn on Adaptive Power and Adaptive Power Notifications.

This is the newer, smarter version of battery saving. Instead of one blunt low-power setting, Adaptive Power watches how you're using the phone and gently throttles things in the background on heavy days, then notifies you when it's doing it. You don't feel it. Your battery percentage does.

Fix 9: Use Low Power Mode Without Shame

Same screen — Settings → Battery → Power Mode — turn on Low Power Mode when you need to stretch the day.

Some people treat Low Power Mode like an emergency-only button. It isn't. Yes, it limits a few things — mail fetch, background activity, some visual effects — but for most of us, on most days, everything we actually care about still works. Long travel day? Battery anxiety at 4 PM? Just turn it on and stop thinking about it.

8 More Tips That Didn't Fit in the Video

These are the extras. None of them require an app, and a couple of them made as much difference for me as the main nine.

1. Check your actual Battery Health. Settings → Battery → Battery Health. If Maximum Capacity is under 80%, no setting on this page will save you — the battery itself is worn out, and a replacement is the real fix. Everything else is decoration.

1. Set Auto-Lock to 30 seconds. Settings → Display & Brightness → Auto-Lock. I found mine had somehow been set to 5 minutes during the update. Five minutes of screen-on time, every single time I put my phone down, adds up shockingly fast.

1. Kill the widgets you never look at. Weather, stocks, news and sports widgets on your Home and Lock Screen refresh themselves constantly. Long-press, remove the ones you added in 2023 and forgot about. Be honest with yourself.

1. Turn off Raise to Wake if your screen keeps lighting up. Settings → Display & Brightness. If your phone lives in your hand or on a desk you bump all day, the screen may be waking dozens of extra times. (This was why my "Home & Lock Screen" usage was so high.)

1. Audit Location Services properly. Settings → Privacy & Security → Location Services. Go app by app. Most apps do not need "Always" — "While Using" or "Never" is fine, and for many, turning off Precise Location is enough. A delivery app knowing your exact house is useful. A wallpaper app knowing it is not.

1. Use Dark Mode if your iPhone has an OLED screen (iPhone X and later, excluding the SE and the non-Pro LCD models). On OLED, dark pixels are literally off pixels. Settings → Display & Brightness → Dark. It won't transform your battery life, but it's free percentage points every day.

1. Prefer Wi-Fi over 5G when signal is weak. A phone hunting for a weak 5G signal in a concrete building is one of the fastest battery drains there is. If you're somewhere with bad reception all day, Settings → Cellular → Cellular Data Options → Voice & Data → LTE will treat you better than 5G On. Or just stay on good Wi-Fi.

1. Charge smarter, not longer. Settings → Battery → Charging — turn on Optimised Charging (or the 80–90% limit if your model offers it). It won't fix today's drain, but heat and constant 100% charges are what wear a battery down over the year, and that's how you end up back on articles like this one.

Questions People Always Ask Me

Why does battery drain get worse right after every update? Two reasons. The background re-indexing I mentioned (temporary, 1–2 days), and the fact that updates sometimes re-enable settings you'd turned off months ago. Background App Refresh and Push mail are the usual suspects.

Will turning off Background App Refresh break my notifications? No. Notifications still arrive normally. Apps just don't pre-load content in the background, so you might wait one extra second when you open them. Worth it.

Is Low Power Mode bad for the battery if I use it every day? No — if anything it's gentle on it. It reduces how hard the phone works and how fast the battery discharges, and slower discharges are kinder to battery health over time.

I did everything here and it still drains. Now what? Check Battery Health (tip 1 above). Under 80% means a worn battery. If health looks fine and drain is still crazy, back up your phone and do a clean restore — it's a last resort, but a corrupted setting carried through an update is a real thing, and a fresh start fixes it.

The Short Version

Most "iOS update killed my battery" problems aren't the update. They're three or four greedy settings — Background App Refresh, Push mail, a forgotten hotspot, a screen stuck on full brightness — all running at once. Fix the settings in this list, give it two days, and check your Battery page again. Mine went from dying by lunch to finishing the day at 30%. Yours should too.

Found this useful? The video version walks through the main 9 fixes on screen, step by step — the link is in my channel. And if a tip here saved your battery, share this page with the friend who's always asking to borrow a charger. You know the one.