I guess the battery just got old, y'know? I mean like plugging them and unplugging them for charge in many sessions would damage it, so I would imagine after 2 - 3 years of doing that, the battery is dying.
Oh I've considered jailbreaking my iPad years back but never did that, kind of prefer not to for carrier issue reasons. how much do the batteries usually run for? maybe the carrier/company would know something about it. i kinda wish i asked my t-mobile guys about why my old phone was so sucky haha