The answer is that you can't turn your phone off whilst charging. It basically goes into a sleep type mode with very little running but it stays awake enough to ensure that the battery doesn't overcharge. It will charge up to 100% and then stop charging, once the charge drops below about 95% it will start charging again and so on. So if you take it off charge in the morning and its only on 96% its not faulty, its just that you took it off before it dropped below the recharge, if that makes sense! (If you stick it back on charge straight away and give it another wee charge it will go up to 100)
