Here’s the cool thing about the iPhone 15: it tells you way more about its battery than older iPhones. Before paying for a new battery, take two minutes to look at what it’s actually saying.
Step 1: Read your battery info
Go to Settings > Battery > Battery Health. On an iPhone 15 you’ll see:
- Maximum Capacity: how much charge it holds compared to new
- Cycle Count: how many full charge cycles it’s done
- Manufacture date and first use date
| What you see | What it means |
|---|---|
| Health 90%+, under 500 cycles | Battery’s fine. Look for other causes |
| Health 80% – 89% | Normal aging. Fine for most people |
| Health under 80% | Worn. Time for a new battery |
Step 2: If the battery’s healthy, find the real drain
- Check what’s using power: Settings > Battery shows which apps used the most. One app eating 40%? That’s your culprit.
- Screen brightness: a bright screen is the number one battery killer. Try Auto-Brightness.
- Background App Refresh: turn it off for apps that don’t need it (Settings > General > Background App Refresh).
- Weak signal: spotty service makes the phone work harder. In a dead zone, Wi-Fi calling helps.
- Just updated iOS? It’s normal for the phone to work in the background for a day or two after an update.
Step 3: Use the 80% limit (optional)
The iPhone 15 can stop charging at 80% every time. Turn it on in Settings > Battery > Charging if you usually have a charger nearby. Less time sitting at 100% means less wear over the long run.
What a cycle actually is
One cycle means you’ve used 100% of the battery’s capacity in total, not that you charged it once. Use 60% today, charge overnight, use 40% tomorrow, and that adds up to one cycle. So topping up throughout the day doesn’t burn through cycles any faster. A phone that’s charged every night for three years might land somewhere around 700 to 900 cycles, depending on how hard it’s used. That’s still under the 1,000 Apple designed it for.
When to replace it
If health is under 80%, or the phone shuts down or slows down even after the fixes above, replace it.
| Where | Price |
|---|---|
| Apple | $99 |
| Apple with AppleCare+ | $0 if under 80% health |
| Independent shop | Often less, but battery quality varies |
Genuine battery or not?
A non-genuine battery shows as an Unknown Part in Settings > General > About, and you can lose the detailed health and cycle readings. For an iPhone 15, where that info is genuinely useful, a genuine battery is worth it.
All iPhone 15 repair prices are on the iPhone 15 page. Apple prices checked October 14, 2026.
