Not too long ago, people would replace their phone every 18 months. But that isn't the case with most people now. According to new estimates, more people are now changing their phones after at least three years. The problem with this is that by the end of two-three years, the battery on the phone reaches a stage where it gets really annoying. Sony has a solution, or so it says. From The Guardian:Sony is trying to fix that, but not by fixing the battery. That's because the lithium ion cells within smartphones don't exactly need fixing -- they will continue to work for years -- but their ability to hold their original amount of charge rapidly diminishes with repeated recharging cycles. Everyone who finds themselves with a chunky battery pack for their new smartphone or desperately searching for a charger by mid-afternoon knows battery capacity is a never-ending headache that only gets worse as a smartphone, and its battery ages. Rather than fixing the battery, Sony wants to do something about the recharging. Jun Makino, Sony mobile's senior product marketing manager, said; "We've started learning your charging cycles so that our new Xperia X smartphones only complete charging to 100% when they estimate you're about to start using them, so that the damage caused by maintaining a battery at 100% is negated. This is important, a battery that's usually kept at a charge between 20% and 80% of its capacity is much healthier -- it's going to the extremes that wears it out at a faster rate. This is important, a battery that's usually kept at a charge between 20% and 80% of its capacity is much healthier - it's going to the extremes that wears it out at a faster rate. The Japanese electronics firm has partnered with Californian adaptive charging company Qnovo to put technology into its Xperia smartphones. This includes the new top-end Xperia XZ and Xperia X Compact, which Sony reckons will double the life of the battery to around four years.