Phone fast charging on a table

Does fast charging affect battery life?

Time is a rare commodity for many of us, so it isn’t surprising that we’d eagerly jump on the fast charging bandwagon. 
However, one thing that’s more important than charge speed is whether your battery will still be ok a year from now. 
We know that some other charging practices can shorten the lives of our batteries, so what about fast charging?

What is fast charging?

Fast charging is exactly how it sounds. It's a charging technique that allows your phone to rapidly gain battery power. It cuts the charging time down significantly compared to standard methods.

To take advantage of it, you'll need a fast charger (that you plug into a power outlet) and a compatible phone.

Fast charging first debuted on high-end flagship phones, but in 2023 it's not uncommon to see it now on mid-range (and a handful of budget) phones.


What is considered fast charging?

It’s all down to the charger’s wattage.

A mobile phone charger with an output of 5 to 10 watts is considered a regular or standard charger.

A charger with an output of 15 watts or more is regarded as a fast charger. At the higher-end, fast charging can have an output of 45 watts! 


Does fast charging damage my battery?

You’d think with all that extra power there could be a risk to your battery. From our findings though, fast charging doesn’t cause any more damage to your phone than standard charging. It will get hotter, but not at extreme enough levels that would cause noticeable harm.  

The main way you’ll damage your phone though is with bad charging technique. Let us explain how charging works and where you could be going wrong.


How charging works

Fast charging takes place in two phases.

The first is designed to give your phone a blast of charge when it is nearly empty, getting you back to half or three-quarter capacity, sometimes in as little as 30 minutes.

Charging then slows down – this is because an empty battery can absorb charge quickly, but an almost full battery cannot.

This phenomenon explains why it takes a phone charger, sometimes up to an hour or more, to give you that last 10%.

Read more: Ultimate Guide to charging your phone


Why you shouldn’t leave your phone plugged in

However, a fully or almost fully charged battery is held in a state of stress that, over time, will reduce battery life. This means if you leave your phone plugged in when at max battery (be it with a fast charger or standard charger), you will damage the battery over time.

If you actively want to extend the battery's life, limiting the amount of time it is at full charge will help.

Read more: How to make your phone battery last longer


Are manufacturers doing anything to protect batteries?

There are two big things manufacturers are doing to help protect your battery. Firstly, better power-saving features. Secondly, less energy-hungry parts and components. These combined will help your battery last longer, which means charging less often.

Furthermore, battery and charging management software on many phones carefully manages the charging cycle.

If you put your phone on charge overnight, the latest phones learn your routine and wait to charge that last 10% just before you wake up. Heat is also bad for battery life and health, and manufacturers may include technology that halts fast charging if the phone and battery are getting too hot.


Should I be using fast charging?

It’s all a matter of preference, but there are no significant issues that should stop you from choosing a fast charging mobile phone. If you want to limit the amount of time your phone is attached to a power cable, fast charging is the solution you are seeking.

If you are on the hunt for a new phone and want one with the best battery, read our guide to phones with the best battery life in 2023.

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