A yellow battery bar means Low Power Mode is on

Your iPhone's battery icon turns yellow when Low Power Mode is active. This is Apple's built-in feature that reduces power consumption to extend how long your phone runs on a single charge. When Low Power Mode is on, your iPhone limits background activity, reduces performance slightly, and dims some visual effects — all to stretch battery life when you're running low.

The yellow color is intentional. Apple uses it as a visual signal that your phone is operating in a reduced-power state, separate from the normal green or black battery icon you see when the phone is running at full capacity. You'll see the yellow bar appear automatically when your battery drops to 20 percent, though you can also turn Low Power Mode on manually at any battery level.

Key Takeaways

  • A yellow battery bar indicates Low Power Mode is active, which limits background activity and performance to save power.
  • Low Power Mode turns on automatically when your battery reaches 20 percent, but you can enable it manually anytime through Settings.
  • While Low Power Mode is on, some features like automatic downloads, mail fetch, and visual effects are reduced or paused.
  • Turning off Low Power Mode restores full performance and returns your battery icon to its normal color.

How Low Power Mode affects your phone's performance

When Low Power Mode is active, your iPhone makes several changes to how it runs. Background app refresh pauses, which means apps won't update their content unless you open them. Mail stops fetching new messages automatically and only checks when you manually open the Mail app. Downloads and iCloud syncing slow down or pause until you turn Low Power Mode off.

You'll also notice that visual effects like animations and transitions become simpler, and some features like Hey Siri voice set up may work differently. Performance itself doesn't drop dramatically — your phone still runs apps and handles tasks — but it prioritizes battery life over speed. Most people don't notice a significant slowdown in everyday use, though demanding apps like games or video editing may feel slightly less responsive.

How to turn Low Power Mode on or off

To manually turn Low Power Mode on, open Settings and tap Battery. You'll see a toggle for Low Power Mode near the top of the screen. Tap it to turn it on (it will turn green when active). You can also access it faster through Control Center: swipe down from the top-right corner of your screen (or up from the bottom on older iPhones), then tap the battery icon to toggle Low Power Mode.

To turn it off, use the same method — go back to Settings > Battery and toggle Low Power Mode off, or tap the battery icon in Control Center again. Your battery icon will return to its normal color once Low Power Mode is disabled. If your battery is below 20 percent and Low Power Mode is on, turning it off will drain your battery faster, so consider waiting until you can charge your phone.

Why your iPhone turned on Low Power Mode automatically

If you didn't manually enable Low Power Mode, your iPhone turned it on because your battery level dropped to 20 percent. This is the automatic threshold Apple set to help you get more use out of your phone before it shuts down. You'll see a notification when this happens, giving you the option to turn it off when ready if you prefer full performance over extended battery life.

Some older iPhones with degraded batteries may trigger Low Power Mode at higher battery percentages — for example, at 30 or 40 percent instead of 20 percent. This happens because the battery's health has declined and the phone can no longer reliably deliver power at full performance. You can check your battery health by going to Settings > Battery > Battery Health & Charging to see the maximum capacity percentage.

When to keep Low Power Mode on versus turning it off

Keep Low Power Mode on if you won't have access to a charger for several hours and need your phone to last as long as possible. It's especially useful during travel, long workdays, or emergencies when you need your phone to stay on. The trade-off is worth it in these situations because you're prioritizing availability over speed.

Turn Low Power Mode off if you're near a charger, need full performance for demanding tasks, or prefer not to have background features paused. If you're using your phone for video calls, gaming, or photo editing, full performance will give you a better experience. You can always turn Low Power Mode back on later if your battery drops again.

Other reasons your battery icon might look different

A red battery icon (rather than yellow) means your battery is critically low, usually below 5 or 10 percent, and your phone may shut down soon. A green battery icon with a lightning bolt means your phone is currently charging. A black or white battery icon (depending on your iPhone model and settings) is the normal state when your phone is not in Low Power Mode and has adequate charge.

If your battery icon is always yellow even after you turn off Low Power Mode, or if it changes colors unexpectedly, restart your iPhone by holding the power button and swiping to power off, then turning it back on. If the problem continues, your battery may be degraded and you may want to check Battery Health in Settings to see if a battery replacement would help.

Frequently Asked Questions

Does Low Power Mode damage my battery?

No. Low Power Mode doesn't harm your battery — it actually helps extend its lifespan by reducing the strain of constant high-performance use. Using Low Power Mode regularly is safe and is one of the recommended ways to maintain battery health over time.

Will Low Power Mode slow down my internet speed?

Low Power Mode doesn't directly slow your internet connection, but it does pause background downloads and may delay when apps refresh their data. Your actual internet speed stays the same, but apps won't fetch new information as frequently.

Can I use Low Power Mode while charging?

Yes, you can keep Low Power Mode on while your phone charges. It will remain active until you manually turn it off. Many people leave it on even while charging if they want to preserve battery health or reduce heat generation during charging.

What happens if I turn off Low Power Mode when my battery is at 15 percent?

Your battery will drain faster once Low Power Mode is off because your phone returns to full performance and background activity resumes. You should have enough time to reach a charger, but your phone will use power more quickly than it did in Low Power Mode.