- Battery health below 80%? The battery is worn — a replacement will fix it
- Battery health above 80% but still draining fast? Likely a setting or app issue
- Check Settings → Battery → Battery Health & Charging first
- Background app activity, screen brightness and location are the main drains
- If the phone also gets hot or shuts off unexpectedly, the battery needs replacing
Step 1: Check your battery health
This is the first thing to do. Go to Settings → Battery → Battery Health & Charging and look at the Maximum Capacity percentage.
- 100–85%: Battery is in good shape — fast drain is probably a settings issue
- 84–80%: Noticeably degraded — you’ll feel the difference, especially on older phones
- Below 80%: Apple considers this significantly degraded — replacement recommended
- Below 75%: This is why your phone dies at lunch
Lithium batteries degrade with every charge cycle. After 500 full charge cycles — roughly 18 months to 2 years of normal use — most iPhone batteries are already below 85%. It’s not a defect, it’s chemistry.
Step 2: Find out which apps are draining it
Go to Settings → Battery and scroll down. You’ll see a list of apps and how much battery each has used in the last 24 hours or last 10 days. Look for anything using a large percentage that you didn’t actively use — that’s an app running in the background without you realising.
Common offenders: social media apps (especially ones with video), navigation apps left running, email accounts set to push rather than fetch, and streaming apps that keep refreshing in the background.
The settings that drain battery fastest
If your battery health is still above 80%, try these before anything else:
Settings → Privacy → Location Services. Set any apps you don’t need to track you to Never or While Using. Apps with “Always” access check your location constantly in the background.
Settings → General → Background App Refresh. Turn this off for any app you don’t need to update in the background. Most apps don’t need it.
The screen is the single biggest battery consumer. Enable Auto-Brightness (Settings → Accessibility → Display & Text Size) so it only goes bright when it needs to.
Settings → Mail → Accounts → Fetch New Data. Change from Push to Fetch (every 30 minutes) for any accounts you don’t need instantly. Push keeps a constant connection open.
5G uses more power than 4G. Settings → Mobile Data → Mobile Data Options → Voice & Data → LTE. Switching to LTE in areas with patchy 5G stops the phone burning power searching for a stronger signal.
Signs the settings aren’t the issue — you need a new battery
If you’ve tried the above and the phone still dies fast, it’s the battery. These signs confirm it:
- Battery percentage drops suddenly — e.g., from 30% to 5% with no warning
- Phone shuts off randomly even when showing charge remaining
- Phone gets noticeably warm while charging or just sitting idle
- Battery health is below 80%
- The back of the phone feels slightly raised or the screen seems to be lifting slightly (this means the battery is swollen — bring it in immediately)
If your iPhone back feels raised or the screen is lifting at the edges, stop using it and bring it in. A swollen battery is under pressure and can rupture. Don’t charge it and don’t put it in your pocket.
Is a battery replacement worth it?
Almost always — yes. An iPhone with a worn battery that otherwise works perfectly is not a reason to buy a new phone. A battery replacement gives the phone another 2–3 years of normal battery life. It’s one of the most cost-effective repairs there is.
At Voltrex we replace iPhone batteries while you wait — most done in 15–20 minutes. We’ll check your battery health when you walk in and tell you exactly what you’re getting.
Walk in for a free battery health check
We’ll check your iPhone battery in 2 minutes and tell you if a replacement will fix it. No charge, no obligation. Clapham Junction — open 7 days.