Our devices are out in the cold a lot. Maybe you ordered a brand-new iPad for the holidays, and the driver left it on your doorstep, or maybe you take your phone with you to skiing, and you take your phone with you. If you have a tech that has a battery that is in below freezing temperatures, do not charge it.
When you charge a battery, what happens?
There are two main issues. When the batteries are below freezing, charging them reduces their capacity permanently. Chemical aging is when batteries lose their maximum capacity. It will seem like it is much older than it really is if you charge a below-freezing battery. Who wants a piece of tech that loses battery power so quickly? No one is the answer.
Charging a battery in such a condition makes it dangerous to use. A battery that is charged below freezing turns into a time bomb. The battery could explode. The battery is destined to fail at some point in the future, and it wouldn't be immediate, but a fiery explosion is not guaranteed.
The information comes from a detailed electrical engineering forum post. The post explains how it all works, including a breakdown of how the batteries work. We encourage you to read their post. This is a very simple description, just to wrap our heads around things.
The batteries can't be charged below freezing.
A battery has two sides. The two sides of the battery are like sponges, they act as a separator for the lithium ion. The battery is discharged when most of the lithium leaves the anode and rests in the cathode.
When charging, the battery moves back and forth. Your device is charged up when most of the lithium makes it back to the anode. With me so far?
When you charge a battery below freezing, the anode doesn't "soak" up the lithium. The anode is covered by the lithium. As the anode naturally expands during charging, the coated lithium forces its way inside. Hopefully, this issue simply results in a battery that fails, however, the process could result in a fire or explosion, which could produce a fire or explosion.
When can you charge your tech?
If you charge a battery in cold temperatures, these issues will not happen. You can charge a battery if the temperature is above 32F.
If you are waiting for a new iPad and the driver leaves it outside of your house on a cold day, you are safe to charge it. If the temperature is below freezing, you should let the iPad sit in the house for a while to make sure the battery is warm. The good news? You only have to wait for it to charge. You can power it on! Since most tech arrives with some level of battery power, you can still get a head-start setting it up.
There isn't much information on how long it takes for a battery to warm up. It is likely that a good rule of thumb is to wait until the device feels better than it did in the cold.
The battery temperature can be checked on the device. A third-party app called Ampere can be used to see if the batteries are above freezing. Many devices don't have access to these types of apps. You probably don't have a tool to open the device and test the battery's temperature manually.
Our advice is not to over think it. If it took too long for batteries to warm up after being outside, you would hear about it a lot more. Wait a bit for your device to warm up before plugging it in.