Why does smartphone battery life get worse and worse as it gets older?

Subject: Reduced battery life with older smartphones and other electronic devices / tips on how to make your battery live longer

Image Credit: SFIO CRACHO via Shutterstock

Image Credit: SFIO CRACHO via Shutterstock

It is an often heard complaint from smartphone, tablet and laptop users. As your device gets older it seems that you can do less and less on a single charge. When it was new you could use it for almost 2 days on a single charge but lately it keeps getting harder to even get trough one day without hooking it to its charger.

As of yet it is impossible to make an everlasting battery, the problem with decreasing battery life over time with current batteries is called capacity loss or capacity fading. Rechargeable batteries lose a little bit of their capacity every time they charge and lose charge.

That loss of capacity is, among other things, a result of the second law of thermodynamics, when you use the battery there is a little bit of waste energy that is lost and can never be recovered.

When you use a lithium ion battery you remove charge away from positively charged ions which makes them move away from the negative electrode. When you put your phone in the wall charger you’ll apply a charge to the ions and they will be attracted to the negative electrode again. In real life there are some components that dissolve over time due to chemical processes in the battery that makes it harder for lithium ions to move back to their initial position.

In addition batteries shrink and swell a very small amount they are charged and discharged which creates tiny cracks in the materials. Eventually small parts of the battery become defective. Those defective parts are no longer able to store ions and thus overall battery capacity and battery life is lost.

Image Credit: Juliasart via Shutterstock

Image Credit: Juliasart via Shutterstock

Here are some tips on how to make your battery live longer:

Try to avoid fast charging as much as possible. Try only to use the fast charger when you are in a hurry and it is absolutely necessary to charge your phone quickly. Charging a phone quickly will reduce its capacity because of the extra heat it generates. It will also slowly damage the fluids inside your battery.

An additional benefit from slow charging is that according to research charging a phone for 2 hours instead of 5 minutes will give it a 20% capacity boost for that specific cycle. Providing you with some extra juice for the day.

Try not to drain your battery all the way to 0%

Lithium Ion batteries don’t like to be discharged completely. Try to charge your battery at 15 to 20% to make it live longer.

Try to avoid any form of heat.

Heat is a battery’s worst enemy. Don’t leave a phone, tablet or laptop in the blazing sun, leave it on the dashboard of your car in front of the windscreen, etc. Also, like mentioned earlier, fast charging generates heat but the same can be said about charging your battery to 100%. It takes more power to put the last lithium ions toward the negative electrode generating waste heat, charging it up to 80% will conserve battery life.

Sources: Journal of power sources, Second law of thermodynamics, Osti.Gov, Battery University

Further reading:

Difference between lithium and alkaline battery (Universal-Sci)


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