An iPhone being chareg
One of the worst things about modern smartphones is the battery life.

Whether you’ve been playing countless hours of Pokemon Go, Snapchatting and browsing Facebook, or just simply taking pictures and sending messages, nothing is more annoying than seeing a red bar on the top right corner of your phone.

The thing is, most of us are charging our phones incorrectly, and it’s partially the phone manufacturers fault. There’s a lot of misinformation out there, and the phone makers have no incentives to educate you on battery life – after all, they want you to replace your phone every two years when your battery is shot.

So let’s get down to some basics. First, most modern smartphones use what’s called a lithium-ion battery, or Li-ion. You can read up on all the specifics on the internal chemistry on Wikipedia, but all you need to know is that Li-ion batteries are the “newcomers” to the battery industry, and they’re much better than the traditional nickel–cadmium batteries that are cylindrical shaped.

In a gist, the batteries in your phone are lithium-ion (Li-ion), and the batteries in your remote are nickel–cadmium (NiCad).

A lot of advices on batteries aren’t necessarily wrong, they just apply to the older NiCad batteries. For example, you should let your NiCad batteries completely discharge before recharging, as the NiCad batteries “remember” the discharge state. This “memory effect,” however, doesn’t apply to the Li-ion batteries in your smartphones.

It’s confusing trying to discern which advices are tailored toward which batteries. So we did a lot of research and crafted a definitive tip sheet for you to follow that will prolong your smartphone batteries. If you have any versions of an iPhone, Galaxy, Nexus, or any other types of modern smartphones, these tips will prolong your battery life:

Do not keep charging your phone once it’s fully charged


This is probably one of the biggest “sins” when it comes to ruining a smartphone’s battery life. A lot of people like to leave their phones completely charged overnight so they have fresh battery for the next day. This is terrible for your phone’s Li-ion batteries.

When you charge a Li-ion battery, it puts to the battery in high voltage stress, forcing the lithium ions to move from the positive side to the negative side (the movement is reversed when you’re using the battery). Even when it’s completely charged, a high stress still weighs on the battery, slowly tearing down the chemicals on the inside.

When it’s fully charged, you should remove the charger. “This is like relaxing the muscles after a strenuous exercise,” Battery University sums it up.

In fact, try to keep your battery level below 100% most of the time

A dissected iPhone. Photo: anandtech.com
This may seem like a vexing advice. What’s the point of having all that battery life if you’re not allowed to charge it to 100%?

Li-ion batteries are pretty flexible, and you can charge them incrementally whenever you have the chance. Battery University writes: “Li-ion does not need to be fully charged as is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge because a high voltage stresses the battery.”

Keeping your phone around ~80% is a good compromise between longterm and short-term performance. Most modern smartphones should last a full day’s use at 80%.

If you’re leaving your phone behind for a prolonged period of time, leave it at 40%

If you’re going to put away your phone for a long period of time (3+ months), make sure to leave your battery level at around 40% before turning it off and stoving it away.

The reason is that your phone will slowly discharge even when it’s off, and you don’t want your phone to completely discharge to 0%. Li-ion batteries are best maintained under moderate stress. So try not to let the battery level near 0% or 100%.

Turn off the device when it gets hot


Binging on Pokemon Go or Clash of Clans may be fun, but prolonged and graphic intensive gaming will heat up the battery and destroy the chemicals on the inside.

“Elevated temperature causes the electrodes in the battery to react with the electrolyte and this will permanently lower the capacity,” writes the Battery University.

The site advices that you “[keep] the devices cool when running them in bed or on a pillow that may restrict the airflow.” If you feel that your phone heat up while playing your nightly bedtime games, turn it off and go to sleep. And don’t forget to place it on the nightstand instead of your bed so that it dissipates heat better.