Being outdoors in minus degrees can have a big impact on your phone’s battery life. Here I thought I would try to find out why this is so and what can be done about it.
Whatever you have one iPhone, Android or any other phone uses basically all smartphones today so called lithium-ion batteries (in English lithium ion, sometimes abbreviated li-ion). These batteries, like all other batteries, rely on chemical reactions to store and release energy.
That just lithium batteries has become standard in everything from mobile phones and tablets to electric cars, both because they can be charged relatively quickly and because they can store a fairly large amount of energy in relation to their size. On the inside, however, it is still, as I said, a chemical process for storing and generating energy. And as with most other chemical processes, so is it lithium batteries sensitive to temperature differences.
A (really) short technical background
One lithium ion battery works briefly in such a way that when used, lithium ions move from the negative pole / electrode of the battery (cathode) to the positive (anode). Extremely simplified, energy is thus produced when the lithium ions moves inside the battery. When the battery is charging, press instead the lithium ions back to the negative pole / electrode of the battery.
So what does that have to do with minus degrees?
Well, under optimal temperature conditions move the lithium ions at a reasonable rate between the two poles of the battery. These optimum temperatures vary between different types of devices and batteries, but are approximately in the range of 16-22 degrees (Celsius). For just iPhone specifies Apple for example that their phones should also be able to handle the range 0-35 degrees without major problems. But that the batteries still thrive best in temperatures a good distance from “zero”.
The farther away from the battery’s optimal temperatures a device is, the harder it gets the lithium ions in the battery to move properly. In the case of minus degrees moves the lithium ions slower between the electrodes of the battery, which can have a variety of outcomes both for the actual battery life but also for the percentage of battery reported to the device in question.
A concrete example is e.g. when one’s phone suddenly dies in cold temperatures. Something that then – probably – comes from not being enough lithium ions managed to reach the positive electrode of the battery. They stop completely on the road, due to the cold. When the phone then enters the heat and the battery reaches a more comfortable temperature, it is not uncommon for the device to start up again and then with a battery percentage far from zero. Simply because the lithium ions started moving again and because there were actually a lot of them left who had not yet moved from the minus to the plus pole.
It is also for the same reason a phone many times reports completely wrong percentages for battery charging at cold temperatures. The phone simply senses the power off lithium ions does not move as fast as it should, something the phone interprets as reducing the battery charge. This explains the large jumps from perhaps 80 percent, down to 10 or even 1 percent battery power as right as it is occurring in cold environments.
The above also answers a bit to the question why a phone can sometimes live for as long as it wants on the last percent of the battery. Something that then comes from the fact that the battery is not actually exhausted, but that the chemical process in the battery has started to go so slowly that the device thinks that the battery is about to run out.
What can be done to avoid bad battery life in the cold?
Unfortunately, the best and most boring tip is to try to avoid exposing your mobile phone, tablet or computer to cold in general. Unfortunately, this is often far from possible and sometimes you need to use your phone, perhaps even in minus degrees.
In these cases, it is important to simply try to minimize the amount of cold the phone is exposed to, by e.g. use a headset and voice control to handle calls and answer messages. Elin Häggberg on Technical lists a few user-friendly tips for just this.
Should I think of something special if my cell phone died of cold?
Yes, do not connect the phone to a charger before it has reached room temperature. To start charging one lithium ion battery which is cold can in the worst case drastically reduce its capacity and if you are really unlucky, even damage the battery. So leave the phone in the heat for a while before charging it. Many times it is enough to let it heat up for a while and then it will probably start up as usual, even without a charger.
Have you experienced that your phone completely gave up due to the cold? Feel free to share your experiences, questions or thoughts in the comments below.
Sources in this article
Battery University: How Do Lithium Batteries Work?
Battery University: Discharging at High and Low Temperatures
Mic: Why your phone dies in really cold temperatures
Lifewire: Safely Using an iPhone in the Snow and Cold