Last night I was tinkering around and my iPad got down to around 18%. I've only had it for a couple of weeks and I've been charging it a lot since the first week I was on vacation. Anyways last night I plugged it in. It powered up. I normally just hold down the power button and then shutdown lock. It kept turning back on and finally after the 3rd or 4th attempt I got annoyed and said fine charge while on. Is there a threshold to which it has to have battery or something? I haven't checked it today since I completely forgot about it this morning.