Why your iPhone's battery life gets shorter over time

It was recently revealed that Apple has been throttling the performance of older iPhones to help preserve battery life. Apple says that as the lithium-ion battery inside the phone degrades over time, the phone and its processor can't draw as much power from it. And if it tries — especially in cold weather or at a low charge — the phone will shut down. To prevent this, Apple is controlling how much power the phones are able to draw.

No matter what type of phone you have, if it's around 2-3 years old then you're probably starting to run into some battery issues. It's all because of chemical reactions inside your phone. Following is a transcript of the video.

Why is it that just a year into your phone’s life it seems like it can barely hold a charge anymore? When looking inside of a battery — you’ll notice a couple of different layers sandwiched together:

Aluminum
Lithium metal-oxide (cathode)
Gel polymer electrolyte
Permeable separator
Gel polymer electrolyte
Graphite (anode)
Copper

All of these materials form three “sections.” A negative side where the potential energy is “stored” A positive section where the “used” energy is collected. And an electrolyte polymer that offers a path for important ions to flow between the two.

A chemical reaction that occurs between the sections are what give the phone its power. First, by turning on your phone you open a path for electrons to flow. Electrons in the anode aren’t happy because they’re in a high-energy state. So, they move to the cathode in search of a lower energy state.

The movement of these electrons is what gives your device energy. But, in the process, these electrons have left their lithium atoms behind. These atoms are now positively charged ions that want to get back to their natural, neutral state. So, they go hunting for their lost electrons — traveling through the electrolyte towards the cathode.
But, when the lonely ion gets there, it can’t find its lost electron. So, the cathode is left with a buildup of positive lithium-ions and their separated electrons.

These ions are what make lithium-ion batteries rechargeable. When you apply electricity to the battery, it forces this electron-chasing process in reverse. The electrons and ions reunite in the anode, ready to release energy once again.

This is described as one full charge cycle. Each time you do this, you wear down the material in the cathode, which means it can’t hold as much electrical charge as before. After 400 charge cycles — your battery will lose 20% of its charging capability. This will happen even faster by continually allowing your battery to get to 0%.  That’s why lithium-ion batteries have a shelf life of about 2-3 years. Also — constantly subjecting your battery to extreme temperatures can significantly reduce battery life.

So, if want your battery to have the longest life possible, Here are a few things you can do:

Turn off phone, wifi, and Bluetooth when you don’t need it
Keep phone at room temperature
Don’t keep brightness at 100%
Turn off battery intense features like facebook autoplay
Use low power mode when possible

This video was originally published on November 29, 2016.