technology has improved with batteries and cellphones over the last 20 years quite a bit. I remember nickel cadmium batteries that built up a memory on improper charges it was really bad . then nickel metal hydride got better with its cells and recharge amounts and little or memory of capacity faults. Now we are onto lithium ion batteries which are yet better but, on the lower end phones the batteries are not high yield or extra capacity due to bulk of users being youth and prefer slim lined for purses and pockets. The cells inside these batteries begin to degrade after so many recharge attempts. Higher end phone models from other brands not sold in most carriers store fronts because the prices are too high for free with activation or upgrades. So the cheaper designe in the lithium ion is what the bulk of us are using . Another money pit! chargers batteries all accessories never being comparable with precious models from the same manufacture. Some are like CAT aka catapillar phones and Nokia Ericson etc.. Hope this helps.