Does how far you discharge your cell phone battery each time influence how long it lasts? You bet it does, but you should treat modern cell phone batteries the opposite way from older-generation cell phone batteries. Read on to learn why and how.
A lot has changed about cell phones and their batteries since cell phones first came out, and getting the most out of your cell phone's battery these days takes a different pattern of care and usage than it did in the time of the old analog cell phones. When cell phones first shrunk down to the point where a phone could fit in someone's pocket (the original analog Motorola flip phone), an "extended" battery, which might allow an hour and a half of talk time on a first-generation flip phone weighed more than the rest of the phone weighed.
The shrinking of cell phones to pocket size caused a significant boom in demand. Less than a decade later, when the first digital cell phones became available, the digital voice compression allowed cell phones to offer both longer battery life, and cheaper air time.
I turn and turn in my cell like a fly that doesn’t know where to die.
—Antonio Gramsci (1891–1937)
One thing has remained constant. People want their cell phone batteries to last as long as they can on each charge, and people want their cell phone batteries to have as long a life as they can before needing to replace the battery. Many people don't realize it, but how you use your cell phone has a significant effect on how many months or years your battery lasts until it needs to be replaced, and how much talk time you will get on your phone each time you charge it.
There are different types of batteries, and each type needs to be treated differently to last a long time. Early-generation cell phones typically came with nickel cadmium batteries. Many early nickel cadmium batteries were prone to develop significant "memory". The phenomenon of "memory" in batteries refers to a behavior of the battery where if the battery is typically only partly discharged (perhaps 25%) before it's charged again, the battery will develop a chemical layering effect internally and will begin to behave as if it is dead when it gets 25% discharged.
What Mrs. Thatcher did for women was to demonstrate that if a woman had enough desire she could do what she wanted, do anything a man could do.... Mrs. Thatcher did not have one traditional feminine cell in her body.
—Julie Burchill (b. 1960)
For those early types of batteries, it was best to occasionally discharge the battery completely (for instance until the phone shut itself off) before recharging it. This tended to reduce the memory effect, and allowed the battery to last the longest, not only on each discharge cycle, but in terms of overall life as well.
Modern cell phone batteries are totally different. Modern cell phone batteries are typically lithium ion batteries. In contrast to nickel cadmium batteries, lithium ion batteries don't have memory, and they don't like to be deeply discharged. Lithium ion batteries are actually degraded much faster the deeper they are discharged on each cycle. While a lithium ion battery might last 600 discharge cycles if it is discharged only half way each time, it might only last 50 discharge cycles if you discharge it all the way every time to the point where the phone automatically shuts itself off.
A good rule of thumb if you want your cell phone battery to last a long time is not to discharge your battery past the point where only one quarter of the battery's charge is left. Of course once your battery does eventually get to the point where it won't hold a decent charge, there is one more good thing to know, and that is where to get an inexpensive replacement. My personal experience has been that the replacement batteries sold through eBay stores work just as well as the replacement batteries sold through cell phone stores, at between half and a quarter of the cost. Happy calling!.