Battery and data on the day you run or cheer
Live tracking eats battery and data at the same time, and a race route runs through the busiest parts of a city. This is how to set both the runner's phone and the supporters' phones up to last the day.
Quick answer
- Live location sharing is the single heaviest drain on race day. Turn it on only when it is needed and shut down other background apps.
- The start and the finish are the most congested points on the network, so agree meeting spots with supporters in advance rather than relying on calls at the time.
- Timings, routes and rules are set by each event's organiser and change from year to year — always check the event's official website.
On race day, battery matters more than data
People running a marathon abroad worry about data, but the thing that runs out first is almost always the battery. Race day combines three heavy drains: GPS running continuously for hours, live location shared with supporters, and a congested network that makes the phone raise its transmit power to hold a cell. All three run at once for the whole time you are on the course.
- Turn off automatic photo backup and unrelated app sync the night before
- Lower the location update frequency if the app allows it — once a minute is plenty for tracking
- If a watch records the run, let the phone do nothing but communicate — far cheaper on power
- Keep a small power bank in the bag drop so you can charge right after finishing
The course and the busiest cells
A big race gathers tens of thousands of people at the start at the same minute, then moves that crowd to pile up again at the finish. Those two points are the worst network of the day — and happen to be the two points where everyone most wants to call each other. The middle of the course is usually better because runners spread out, though pockets with dense spectator crowds slow down too.
| Point in the day | Network condition | What to do |
|---|---|---|
| In the start pens | The worst of the day; messages can lag by minutes | Send your "starting now" message before entering the pens |
| Out on the course | Better once runners spread out, except at dense spectator points | Let location sharing run and leave other apps closed |
| The finish and the recovery area | Congested again, with everybody calling at once | Walk to the agreed meeting point instead of calling |
| Later that evening | Back to normal | A good window to upload the day's photos and video |
A general picture of how large races behave, not a measurement from any specific event.
What the supporters need to arrange
Supporters often have the harder job: moving between points on the course using public transport that road closures have disrupted, watching a live tracker, and working out whether they can reach the next spot in time — all on one phone whose battery must last until evening. The most effective preparation is choosing the viewing spots in advance and learning the routes between them the night before.
- 1Days before: read everything the organiser publishesThe route, road closures, wave start times and bag-drop rules are all set by the organiser and differ every year. Read them on the event's official website and nowhere else.
- 2The night before: strip the phone downCharge fully, turn off automatic backups, stop sync for apps you will not use, and download offline maps of the area around the course.
- 3The night before: agree meeting points with supportersPick something easy to see that is not the spot everyone picks, and agree a backup time in case the finish comes earlier or later than expected.
- 4Race morning: send the important messages before the pensSend your bib number, expected start time and tracking link to supporters before you walk into the densest part of the day.
- 5After finishing: charge first, upload laterCollect the power bank from the bag drop and charge straight away; leave photo and video uploads until you are back on Wi-Fi.
What race day actually consumes
Location sharing uses less data than people assume, because a set of coordinates is tiny. What actually consumes is the video and photos exchanged during the day, and supporters reloading a results page over and over. The figures below are planning estimates, not measurements from your own device.
- Four hours of live location sharing: roughly 50–150MB
- A supporter with maps and a tracker open all day: roughly 1–2GB
- Ten short video clips to a family group: roughly 200–600MB
- Uploading the day's media in the evening: roughly 1–3GB if done on mobile data
FAQ
Does live location sharing use a lot of data?+
Not much — a set of coordinates is tiny. What it does consume heavily is battery, because GPS and transmission run continuously. If you must economise on one thing on race day, economise on power.
Why can we not call each other at the finish, standing metres apart?+
Because the cells there are past capacity: a call needs a channel reserved for it and none is free. The distance between you is irrelevant. What works is walking to the meeting point you agreed before the race.
eSIM or hotel Wi-Fi for following the results?+
If you will be in the hotel, Wi-Fi is fine. But a supporter moving along the course is outside for nearly the whole day and on mobile data almost continuously — budget for the whole day, not just the morning.
Where do I find the timings and the route?+
Only on that event's official website. Wave start times, the route, road closures and access rules are set by the organiser and change from year to year, so we do not state them here.
Instagram and TikTok have no web share button, so we open your phone's share sheet or copy the link instead.