Does Always-On Display affect GPS battery life on a hike?
Always-On Display draws a little extra power for as long as a hike lasts, because it keeps the screen lit at low brightness instead of letting it go dark. What it does not do is change anything about GPS tracking itself — a route records at the same rate whether the screen is fully off, dimly lit, or showing something in another app entirely. The two are separate systems on the phone, and only one of them cares what the screen is doing.
The short answer
Yes, Always-On Display costs some battery on a long hike, the same way it costs some battery on any day you carry the phone — a dimmed screen is still a screen that is drawing power, where a screen that has gone properly dark is not. It does not, however, affect GPS tracking in any way. Route recording depends on the GPS chip and the app doing the recording, neither of which is switched on or off by whether the display panel is lit.
Turning Always-On Display off before a full day out saves a small amount of battery for the length of the hike and changes nothing else about the walk being recorded.
What Always-On Display actually does
On the iPhone models that support it, Always-On Display keeps the lock screen visible all the time instead of letting the screen go black when it is not in use — the time, wallpaper and any widgets stay on screen at a much lower brightness, and the display returns to full brightness the moment you raise the phone, tap it, or press the side button. It is a display setting, reached under Settings, Display & Brightness, and turning it off simply lets the screen go dark the way it does on a phone that never had the feature at all.
A screen kept dimly lit the entire time is a small but continuous draw that a screen sitting fully off does not have. Over the length of a short walk that difference is not worth noticing. Over a full day on trail, with a phone that started the hike on Always-On by habit rather than by choice, it adds up the same way any always-on setting does.
Why this has nothing to do with GPS tracking
A route being recorded and a screen being lit are two different jobs running on two different parts of the phone. The GPS chip keeps receiving satellite signals and the recording app keeps logging points on whatever schedule it uses, entirely independent of what is being drawn on the display at that moment — the same way a phone call keeps going while the screen is off, because the two were never linked. A recording app built to keep working with the screen off or the phone in a pocket has no reason to check whether the lock screen happens to be visible; it was never part of the decision.
That is why turning Always-On Display on or off changes a battery number and nothing on the map. The track that comes back at the end of the hike has the same points, spaced the same way, whichever setting was chosen at the start.
Where the two settings do meet, briefly
Low Power Mode turns Always-On Display off automatically, along with a handful of other things that draw a small continuous amount of power, for as long as Low Power Mode stays on. That is Apple's own behaviour, not something a hiking app has any part in — Low Power Mode is deciding to trim a display feature, not making any decision about GPS. If a phone is already running low partway through a hike and Low Power Mode gets switched on to stretch what is left, Always-On Display switching off along with it is a side effect of that one setting, not a separate step to take.
Things that trip people up
- Assuming a lower battery percentage at the end of a hike with Always-On turned on means the GPS track suffered along with it — it did not; the battery draw and the recording are unrelated, and the track is unaffected either way.
- Turning Always-On Display off mid-hike expecting the route to somehow record more accurately from that point on — accuracy was never tied to the display setting, so nothing about the track changes.
- Confusing Always-On Display with the screen simply being locked — a locked screen with Always-On off goes properly dark and draws less power than a locked screen with Always-On display showing the clock and wallpaper.
- Not realising Low Power Mode already turns Always-On Display off on its own, and manually turning it off too, which changes nothing further.
Where TrailCam fits in
TrailCam keeps recording a route while the screen is off or you are in another app, so whatever the lock screen is doing — fully dark, or lit at low brightness under Always-On Display — has no bearing on the track that comes back at the end of the walk. Turning Always-On Display off before a long day out is purely a battery decision, worth making on the days battery is genuinely tight and skippable on the days it is not. TrailCam is free to download.
Questions
- Does turning off Always-On Display make GPS tracking more accurate?
- No. Always-On Display only changes what the lock screen looks like when the phone is idle. GPS tracking runs on the GPS chip and the recording app, independent of the display, so the track is identical either way.
- Is Always-On Display worth turning off for a long hike?
- It saves a small amount of battery over the course of a full day, since a dimly lit screen still draws more power than a screen that has gone dark. On a short walk the difference is not worth noticing; on a long day with tight battery it can be worth the toggle.
- Does Low Power Mode already handle this?
- Yes. Low Power Mode turns Always-On Display off automatically for as long as it stays on, alongside a few other small continuous power draws, so switching it off by hand as well makes no further difference.
Recording your own routes
TrailCam is an iPhone app that records your route with GPS, keeps video clips, photos and voice notes pinned to the spot where you took them, and exports the result as GPX 1.1 or CSV. It is free to download.