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Is It Bad To Fully Charge Your Smartphone?
- May 22, 2018 -

With greater ease of charging via wireless technology, the question becomes: Is it bad for your mobile device battery to be fully wireless charged all the time?

 

Venkat Srinivasan, director of the Argonne Collaborative Center for Energy Storage Science (ACCESS), said that while you cannot overcharge a smartphone or tablet battery, as the electronics will not allow it, keeping it fully charged will hasten its degradation.

 

"Frankly, the higher you are in the [wireless charging] state, as you creep up to 90%, 95% to 100% charge, the more degradation the battery will see," he said.

 

As a lithium-ion battery charges and discharges, ions pass back and forth between a positive electrode (made of lithium-cobalt oxide or lithium iron phosphate) and a negative electrode (made of carbon graphite).

 

As a battery charges,  the positive electrode gives off lithium ions that move to the negative electrode and are stored as energy. As the battery discharges, those ions move back to the positive electrode to be used as electricity. As those lithium ions move back and forth, the electrolyte that acts as the transport medium degrades over time.

 

The higher the state of charge, the faster the electrolyte degrades, Srinivasan said.

Therefore, it's best not only to keep your smartphone below its top charge, but also to keep the charging and discharging pendulum from swinging wildly.

 

"In general, if you swing the battery charge from top to bottom, that's the worst thing you can to for the life of the battery. If you can cycle the battery between 45% and 55% that's the best thing you can do," Srinivasan said. "But, in general, just make sure you don't keep it fully charged."

Srinivasan also cautions against being too sensitive to your smartphone or tablet charging. Most smartphone manufacturers design batteries to last two to three years, so if you're a consumer who typically replaces your phone after that amount of time, you don't need to be overly concerned with charging rates.