What Exactly Is A Battery Charge Cycle?

[vc_row][vc_column][vc_column_text]I've wondered on this one for a while. I'm aware that batteries with a Li-Ion / Li-Polymer chemistry can only be charged a certain number of times (cycles as it's known) before capacity starts to reduce but I wondered whether topping your phone up at 70% would basically use up a full cycle. Not the case according to Apple marketing. I'm not sure whether to believe technical information from marketing. Is this true or not? The text below is just a quote from the MacWorld website that caught my interest while sat on the train.“Sadly, there are some inaccurate reports out there,” Apple marketing vice president Greg Joswiak told me today during a brief phone call from New York City. Joswiak isn’t quite sure where the story went off the rails — David Pogue’s initial New York Times review of the iPhone mentioned the battery issue, but Pogue got it right: “Apple says that the battery starts to lose capacity after 300 or 400 charges.”Somehow, though, things got lost in translation. And follow-on reports started claiming that 300 to 400 charges would be the end of the line.“After 400 complete cycles, the iPhone’s battery still has 80 percent of its charged capacity,” Joswiak said. “And by a complete charge cycle, I mean completely draining the battery, a full chemical cycle.” In other words, using a little battery and then putting your iPhone back in its dock doesn’t count as a charge cycle. If you use a quarter of your iPhone’s battery and then re-charge it, Joswiak said, that’s the equivalent of a quarter of a charge cycle.“If you top it off, you’re not wasting a charge cycle,” Joswiak said.Interesting but I'm still curious to know how accurate this is. Any clues?The text here is taken from the MacWorld website.[/vc_column_text][/vc_column][/vc_row]