Outdoor smartphone usage

Outdoor smartphone use has been a highly debated topic pretty much since the popularization of the smartphone with the iPhone in 2007. It continued the already discussed topic of how reliable handheld GPS devices are and whether they can be replace map and compass. There is a lot of prejudice, out-of-date information and misunderstandings about whether and how helpful a smartphone can be when you are in the outdoors. But also, many people seem to not make use of the full capabilities that a smartphone has.

As a passionate hiker who is also into IT stuff, my position is clear: Smarphones are higly useful machines that simplify our (outdoor) lives to a huge extent, and I would not recommend anyone to leave his smartphone at home. My perspective is that of a hiker doing day and long distance trails in very common but also very remote areas, in the mountains or flatlands.

This article is a guide on how to use your smartphone outdoors and make the most out of it, but also what precautions are required.

Power consumption and poor battery life

Modern smartphones generally do not have a long battery runtime; daily recharging is necessary for many users. Being outdoors, sparse network coverage and frequent GNSS usage will decrease battery life even more. With the right precautions though, runtimes of up to a week are possible.

Generally, everything your phone does (or you do with it) requires power. If you follow the recommendations below, this will reduce the passive power consumption. But any actual activity like making a phone call, scrolling a website, playing a game, listening to music, will use drastic amounts of energy. The best power saving technique is therefore to deactivate passive consumption and otherwise not use the phone.

Cellular network

A mobile phone is constantly in exchange with the base stations of the cell network to be available to incoming calls and to transmit data. When the signal is weak, the phone will require more energy to register with the cell network, but also to transmit data (for internet usage) or phone calls. This is e.g. the case when you are in a rural region and cell towers are sparsely distributed, when you are in a train or bus and the phone is constantly looking for new cell towers, or when you are deep in a building or gorge with walls that attenuate the signal.

This communication with the cell network is one of the main energy drains of an idle phone! E.g., whenever I am in the rehearsal room, power consumption easily triples due to being in the basement of a steel-concrete building. You can reduce the power consumption in two ways.

First, you can switch off mobile data. This will reduce background transmissions like synchronizing mails and messages (threema, whatsapp, signal, etc.). Even better, go into flight mode. Then no registration will happen whatsoever and the phone saves a lot of energy.

The conclusion from this is easy: When not required, switch on flight mode. This will turn off cellular network and drastically reduce power consumption.

Note that this means that you will not receive any new messages and you will not be able to be reached by phone. Furthermore, be aware of the safety implications, as noted out in emergencies.

Background applications

A smartphone is full of applications that, even when not visible, perform actions in the background. This includes messengers like signal or whatsapp, which are constantly running in the background to check for new messages. But also many other applications run tasks in the background, e.g. the music player searching for new media files. To perform these tasks, the CPU (the main processor of the phone) has to work, which in turn consumes power.

This is where the energy saving mode of the phone comes into play. This mode will, among other measures like decrease the display brightness, stop background processes from running. On Android, you can activate it by dragging down the menu from the top of your screen where there should be a button for energy saving.

Foreground applications

Applications running in the foreground will not be blocked from running by using the energy saving mode. You just have to be aware that when an application is running in the foreground, it will perform actions that lead to an increased use of energy. It is not always avoidable, e.g., for navigation, but whenever you can, close foreground applications. That means, go into the app overview (on the bottom left or right of the phone) and close applications you do not need. When you do not need to look at an application frequently, go back to the start screen.

External devices

External devices communicating with the phone require power. This comprises wired devices (like headphones or flash drives) which are powered by the phone itself. But also wireless devices (heapdhones, sport watches, cameras) require your phone to constantly communicate with them, requiring processing and transmission power. Therefore, keep the use of external devices as low as possible to save energy.

Summary: Saving energy

To summarize, to save energy

This way, my phone instead of one day can easily last one week (without active use).

Reliability and dependency, protection of the phone

One of the big issues arising from being dependent on the phone without understanding it and without having alternatives in case it fails, maybe up to the level of having the life in danger. Some short words therefore on how to increase the reliability of the phone.

General reliability

As a very imprecise but helpful rule of thumb, devices are prone to failing at the very beginning of their lifetime, then reach a state of low failure rates, which increases with a longer lifetime again. If you would be going to depend heavily on your phone, you should neither take the phone you just bought last week, nor should you use your five year old phone which you already dropped five times on the concrete floor.

Protection against impact

How robust a phone is, and what protection it needs when going outdoors, is often blurred by personal experiences ("I dropped my phone five times already and nothing happened") and manufacturer promises and marketing.

While outdoor smartphones are particularly protected, you have to know yourself what protection your personal behavior requires. There are people who drop their phones on a daily basis, others never do it. The surfaces you encounter in an urban life like concrete or tiles are generally tougher than those you would encounter outdoors, where vegetation makes a lot of rather soft surfaces.

However, the right-angledness of surfaces in urban life rarely pose a danger to a phone screen since the corners and edges mostly hit the ground first. Unregular surfaces like rocks or gravel make it more likely to hit your screen on a drop. A solid screen protector is the most useful impact protection.

Protection against water and dust.

Many modern phones (especially high-priced models) are already protected against dust and water up to a certain point, even a diving depth of several meters. If in doubt, consult the manufacturer's specifications. The water- and dust-proofing is normally given by MIL or IP with some numbers attached. The number refers to how protected the phone is, and you can look it up easily in the internet.

Losing the phone.

The danger of losing your phone is significant. There are rivers, deep lakes and abysses, unreachable gaps between stones, etc. If you are a person that likes to drop devices, you should re-consider your behavior or even attach a cord to the phone or similar. All this happens easily and can mean that the phone would be lost irrecoverably.

Harsh conditions

Under unfavourable conditions, your phone might become temporarily unusable. E.g., when there is heavy rain, you will not find a spot where you can store your phone in an accessible way so that it would stay dry, and you might have trouble to use your phone anyway because your hands will not become dry. Be prepared to not be able to use your phone under bad weather conditions.


The usefulness of a phone in critical cases is easy: You can look up information, you can call for help and you can be located. If you got lost or do not know how to open a hut, etc., going to the right spot to get localization or an internet connection might solve the issue. When you or somebody else is in trouble and you are still able to move or at least to use your phone, you can use it to call for help. See the section about signal transmission for details on where this is more likely to happen.

However, there are cases in which you would not be able to call for help anymore, being unconscious, too weak, or simply asleep. In those cases, the phone will help you to be located by others. Some search and rescue organizations use mobile IMSI catchers to find people: These dvices act like a celltower, and your phone will register to them if they are in reach. So even if you are in a region without cell phone coverage, your phone might be able to register to a passing-by airplane or helicopter and therefore you will be able to be located.

Therefore, always switch off flight mode when you encounter a situation that could potentially be dangerous. Carry your phone on your body, rather than having it in the backpack, where it could be potentially separated from you.

Note: At the time of writing, November 2022, two new phones from Apple and Xiaomi just came out that integrate satellite services for emergencies. My personal impression is that this will come to more high-end phones in the future, but it will still be a rather rare feature due to the costs (and probably rather limited use for a majority of people who buy phones in that price range). Of course this does not rely on cellular network for calling for help. However, the concepts named later apply to receiving satellite signals and should be considered when you are using satellite services for emergencies.

Using the phone at its best

Going away from mitigating the negative impact of using a smartphone, there is some things to consider to make optimal use of the phone.

Receiving and sending signals

The main functionality of a smartphone is based on sending or receiving wireless signals, i.e., the usage of the cellphone network or GNSS (e.g., GPS) for localization. However, both is likely to be impaired in many situations you face outdoors if you don't know where to look.

The main principle of transmitting cell phone data is that a clear line of sight with a base station is the best coverage you can achieve. It is mostly the case when you are on saddles, on crests, on peaks, etc., where you have a wide overview of the surrounding landscape. This will increase the chances of seeing a cellphone tower, or at least having a more direct view on one than in a valley. The second principle to look out for is of course man-made areas. A village or even an antenna tower will increase the likelihood of the presence of a base station.

For GNSS coverage, the principle is slightly different. GNSS is based on receiving the signal of multiple satellites in diverse positions. The more diverse the position is, and the more satellites are seen, the better is the signal.
As a consequence, a direct line of sight with something is not as important, but rather seeing a big amount of sky to increase the amount of satellites, the span of their positions, and the duration during which they are seen. Anything that blocks the phone's view to the sky will impair the signal, like

The same rule of thumb as for cell network connectivity is applied here though: The higher you are, the better are your chances, like on saddles, peaks, crests, or flat landscapes. When inside structures, hold your phone towards the windows or slightly outside.

Another big factor is simply the country or region you live in. Some countries have a very dense network, while others (e.g., Germany) have a really poor one. If you are in doubt about connectivity, you can check the phone providers of the country. They often offer a connectivity map where you can see an approximation of where you should be able to receive their networks. E.g., the one from Swisscom and the one from Sunrise.

Note that connectivity is mainly a matter of topography. You can spot these spots already when planning a tour, to prepare e.g. to download the weather data and messages when you are crossing a pass.

Localization and maps

The probably simplest use of a smartphone outdoors is for localization and maps. You will still hear arguments that you should always carry along maps and compass over using GNSS. It is up to the hiker to decide what they need in the region they are going to. In well-visited regions many people go without a map at all, in others, even a map will not help in finding the way.

In the section about receiving signals it is already described how to optimize GNSS localization. Under bad conditions, either the localization does not work at all, or the precision is reduced. Unfortunately, this often happens rather intransparent to the user, so that it is not clear how good the precision actually is. Depending on the smartphone model and the received signal, you can be off by several tens of meters! Take this into account when the smartphone tells you that you are on a trail you do not see, as it might actually be twenty meters above you...

When visiting a foreign country, it is advisable to not only rely on general map sources like openstreetmaps or google maps, but research if there are other applications. E.g., for Switzerland there is swisstopo, for Norway there is, etc. As noted in the section about offline usage, not all map applications allow the use when offline, google maps being the prime example with only a small area that can be downloaded. For me, in Switzerland and nearby Italy, swisstopo is by far uncontended. In Norway, a combination of and Openstreetmaps (via OsmAnd) did the job very well.

When the favourite maps are not available as an app, you often have the possibility to download them, or in the worst case, make a screenshot and save them on the phone. Big mapping applications (like swisstopo) offer to render a print of the current cut. This can be helpful if you do not want to use the app or want to look at maps that cannot be displayed with the app.

Weather and other information

A big benefit on multi-day hikes is weather forecasts. Often local weather forecast services exist that are more reliable and precise than the generic global ones, like for Norway or MeteoSuisse for Switzerland.

Two things are there to remember: * You need internet access for downloading the forecasts! If you have been offline for some days, you might be seeing the weather forecasts for the current time, just that it is several days old - and probably totally inaccurate. * Often weather services will not be able to find your precise position. Get the forecast for mountains and villages around your hiking route to get a better picture of how the weather should be.

Preparations for outdoor usage

Since the next power outlet and internet connectivity might be far on your trip, you should prepare certain situations.

Calibrate and know your battery

Battery behavior can be weird. The percentage given to you by the phone software is just an approximation based on the cell's voltage and "learned" behavior. In particular old batteries can behave unexpectedly. It is common to have the battery being shown to be at 20%, but then suddenly drop dead. On the other hand, a battery might be drowning down to 1%, but then remain there for hours.

Let your phone run dead once or twice to actually understand this behavior. This also helps the battery electronics re-calibrate and improve at showing the proper percentage.

The same holds for powerbanks, if you take one with you. Use it for charging your phone for some time to let it run dry and know its actual capacity.

Know your phone's features

Some phones have functionality to wirelessly charge other phones. This can be helpful if somebody else's phone drops dead and you know this would work but don't have a cable. The same holds the other way round, being able to charge wirelessly can be helpful in certain situations. Be aware however, that wireless charging is less efficient than wired charging. Especially when you go into huts or with other people, expect to find all kinds of different USB ports and other people with dead phones and no fitting cable. You can buy microUSB/USB-C/USB-A/Lightning adapters with virtually no weight for about 1 CHF from aliexpress which allow you to adapt from any port to any port.

Also check about the mentioned emergency satellite function that some few new phones provide.

Offline phone usage

Depending on the area you go to outdoors, there might be no cell network available. Many applications that normally work well might behave unexpected, maybe not working at all, and you should better not be caught unexpected.

Caching applications

Some applications automatically cache data, i.e. store them teporarily, and oftentimes without your control. One of these examples at time of trying it out (August 2022) is the app. You cannot explicitly download certain map tiles, theoretically making it unusable offline. But you can, by zooming in to the appropriate level and then strafing over the map slowly until it shows the proper maps, make the application download the tiles. They will stay available after the application has been closed and you are offline though.

With caching, you have to be careful. You never know how much an application can cache. At some point, it might start deleting older map tiles to make space for new ones. Especially between restarts of the app or even the phone, this is more likely to happen.

Saving data beforehand

Being offline means, well, that you cannot access any online data. ;-) Some map apps allow you to download map data so you can use it offline (OsmAnd, swisstopo). But also entertainment is something that could be nice to have. Many magazines can be downloaded as PDFs, and browsers support saving websites offline. Also with videos and podcasts, remember to store them on your phone if you might be needing entertainment.

Opportunistic communication

The main concept to understand when dealing with modern phone messaging (including threema, signal, whatsapp) is that it is opportunistic communication. This means the communication happens whenever there is the opportunity.

When you go online, you will send and receive messages in nearly real-time, meaning that when you send a message, only seconds later the other side can see the messages. Vice versa, messages that are sent to you will be received within seconds on the other side, provided they are online.

When your phone is offline, it will neither receive nor write messages, but you can continue to write them as others will continue sending messages to you. Once your phone goes online, it will receive outstanding messages and send the ones you wrote in the meantime.

It sounds pretty obvious, but it makes sense to understand and memorize it. You can e.g. write all the messages to your friends while being in flight mode in a warm hut. And once you are on a windy and cold pass with cellphone reception, you switch off flight mode and it will be sent. At the same time however, others will continue sending you messages. It might be you are discussing something, but you only respond to messages that are long gone and forgotten, but they will see it like a current topic.

Poor bandwidth

Even when you have connectivity, it is often rather poor. You will find that some applications do not work at all with low bandwidth, others might be unusably slow. Android phones have a "data saving mode". This will deactivate background data usage, which shuts off all the apps transmitting data in the background, including:

When the bandwidth is low and the phone tries to perform these tasks, there will naturally be less bandwidth for the foreground application (that is the one you see on the screen). If you activate the data saving mode, only the foreground application can access the internet. This also means that to receive messages for a certain app (like threema or your e-mail client) you need to open this app and keep it open for a while to make sure that it has synchronized the data at the low bandwidth you have. If you are in a rush or in a foreign country where you need to save data volume, you can use the data saving mode. Otherwise, I recommend to leave it off due to the unwanted side effects.