Does Letting A Phone Discharge Completely Before Charging It Again Improve Its Battery Life?

I am quite sure that, in today’s world, you run a better chance of finding a person who has painted himself purple and is dancing naked in the middle of the road than finding someone who doesn’t have a single electronic device in their possession… such is the ubiquity of tech gadgets these days!

Now, anyone who owns an electronic device, whether it’s a smartphone, tablet, laptop, a pair of wireless speakers or any other piece of tech, experiences plenty of challenges that are common to every other gadget owner. The biggest of those challenges, in my humble opinion, is the problem of battery life.

We all know of that ominous feeling when we’re just about to send that last line of a text message or replying to an ultra-important email when the phone/laptop battery announces that it’s about to die on you…

In a bid to tackle this omnipresent battery problem, one of the ‘tricks’ that people use is to let the battery discharge completely and then plug it in to charge it again. The question is, does that actually help?

Does discharging the phone completely before recharging it improve its battery life?

Short answer: No, using up all the juice in the battery before recharging does not help extend its life. Modern lithium-ion (Li-ion) batteries, which are used in smartphones and laptops, do not take too well to being used up completely before they’re recharged. In fact, this practice adversely affects their longevity and is, therefore, counterproductive.

Mobile low batery

Photo Credit : Bloomua / Shutterstock

Since most modern electronic devices, including smartphones, laptops, tablets, Bluetooth headphones etc. use Lithium-ion batteries, it helps if we first understand how these batteries work.

How do Lithium-ion batteries work?

Lithium-ion batteries, often abbreviated as Li-ion batteries, rely on Lithium ions (hence the name) to act as a crucial component in their electrochemistry. Like all batteries, a Li-ion battery also has two terminals, namely, the anode and cathode, separated by an electrolyte (a liquid that dissociates into ions in solution and thus acquires the ability to conduct electricity).

When a Li-ion battery is a part of a completed circuit (when it’s placed inside a phone/laptop), positively-charged Lithium ions move towards the cathode, which is negatively charged. Hence, the cathode becomes more positively charged, which causes electrons from the anode to move towards the cathode (where electrons are less in number).

Now, the electrons want to reach the cathode as quickly as possible by taking the shortest route possible, but the electrolyte in between the electrodes prevents them from doing so. Instead, these electrons are ‘forced’ to flow through the device in question (i.e., phone, laptop etc.), which powers the device in the process.

To understand how this works, think of how a water wheel rotates when fast-flowing water is made to flow over it. In the case of a Li-ion battery, the fast-flowing water represents moving electrons and the water wheel represents the device (e.g., phone, laptop) that you are using.

water wheel

A water wheel (Image Credit: Wikimedia Commons)

What happens when a Li-ion battery is recharged?

Since Li-ion batteries are rechargeable, they can be used over and over again by juicing them up. This is done by connecting them to a power supply. When a Li-ion battery is connected to a charger, Lithium ions flow in the opposite direction, i.e., from the cathode to the anode, until the anode again holds a great deal of Lithium ions. At this point, the battery shows a charge of 100%.

Why is discharging a Li-ion battery completely not recommended?

Discharging your gadget completely (which most likely contains a Li-ion battery) before plugging it in again to recharge is certainly not a healthy practice, as far as battery life is concerned. This is because it could lead to problems like mechanical degradation of the cathode or side reactions with the electrode or electrolyte solution. Needless to say, such internal issues cut short the battery life by a considerable extent.

Note that your battery wears down by a small extent every time it’s discharged/recharged completely. If you drain your battery from 100% to all the way down to 0%, it’s likely that it could potentially degrade by up to 70% of its original capacity in just 300-500 discharge/charge cycles.

In a nutshell, you do your phone battery more harm than good if you let it drop to 1-2% charge every time before recharging it. The best thing to do. therefore, to extend the battery life of your device is to operate it between a charge range of 30-80% (Source)

References:

  1. Lithium-ion Battery – Wikipedia
  2. Rechargeable Battery – Wikipedia
  3. Lithium-ion Battery – Clean Energy Institute (University of Washington)
  4. Battery University
  5. Popular Mechanics
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About the Author:

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spends a lot of time watching movies, and an awful lot more time discussing them. He likes Harry Potter and the Avengers, and obsesses over how thoroughly Science dictates every aspect of life… in this universe, at least.

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