Does closing other apps help GPS battery life on a hike?

The short answer

Closing other apps before or during a hike makes little to no difference to GPS battery life. The app switcher is a list of recent apps, not a list of apps currently running — most of what is in it is paused, using no processor time and no meaningful power, whether you swipe it away or leave it there. What actually determines how much battery a tracked route costs is the screen, the GPS receiver, and the cellular radio, not how tidy the switcher looks.

What "open" actually means on iOS

Swipe up and hold to see the app switcher, and every app you have used recently appears there as a snapshot — a picture of what its screen last looked like. That snapshot is not proof the app is running. iOS suspends an app almost immediately after you leave it: its process is frozen in memory, holding its place so it can resume instantly if you switch back, but not executing any code and not drawing any power in that state. A handful of apps get an exception for a specific, limited reason — one playing audio, one that has asked to keep recording location, one finishing a short background task — and only those keep doing anything at all while off-screen.

A tracking app is one of the exceptions on purpose. TrailCam keeps recording position in the background because you told it to, by starting a route — that is a deliberate, ongoing task, not the kind of thing a frozen, suspended app does. Nothing about that depends on what else is sitting in the switcher underneath it.

Why closing an app can cost more than leaving it

Swiping an app away in the switcher does not just pause it harder — it ends its process entirely, discarding whatever state it had in memory. The next time you open that app, iOS has to launch it from scratch: reload its code, rebuild its screens, reconnect to whatever it was doing before. That relaunch is a genuine, if brief, burst of processor activity, and it is more expensive than simply resuming an app that was quietly frozen in memory the whole time. Habitually closing every app between uses trades a series of small relaunch costs for a saving that was never really there to begin with.

What the app switcher has nothing to do with

The GPS receiver in an iPhone is a single piece of hardware shared by the whole system, and it responds to requests from whichever apps have asked for location — not to how many apps happen to be listed in the switcher. Whether the switcher shows two apps or twenty, TrailCam requests position updates at the same rate either way, because that request has nothing to do with the other apps at all; it is a conversation between TrailCam and iOS, not a resource being split among everything you have used that day.

What actually moves the needle

The things genuinely worth managing on a long day are the screen, which is the single biggest power draw on the phone by a wide margin, and the cellular radio, which can spend real power hunting for a signal it cannot find in poor coverage — airplane mode heads that off while leaving location working. The GPS receiver itself is a modest, steady draw next to either of those. None of that list includes how many apps are sitting unused in the switcher, which is why tidying it up before a hike tends to feel productive without actually changing the battery figure at the end of the day.

Things that trip people up

• Treating the app switcher as a list of apps currently running — it is a list of recently used apps, and most of what is in it is frozen, not running.
• Swiping away everything before a hike expecting a noticeable battery saving — the saving is usually too small to notice, and the relaunch cost of reopening those apps later works slightly against it.
• Worrying that other apps are "competing" with a tracking app for the GPS receiver — the receiver responds to whichever apps have requested location, not to how many apps are merely open in the background.
• Confusing a suspended app with Background App Refresh, which is a separate setting that lets a specific app do limited work off-screen — closing an app in the switcher and turning off its background refresh are two different things with two different effects.

Where TrailCam fits in

TrailCam keeps recording a route in the background whether the screen is off, another app is in the foreground, or half a dozen other apps are sitting untouched in the switcher underneath it — none of that affects the track or the battery it costs to keep recording. The more useful habit for a long day is the one that actually changes the power budget: turning on airplane mode out of coverage, keeping the screen off between checks, and letting the phone sit rather than swiping through it. TrailCam is free to download.