Batteries loses their capacity over time. A dead battery will also show similar voltage as a new battery but when it gets current drawn its voltage will drop deadly. When battery is dead it will start drawing more current in charging period. While you ride your bike your stator windings of your bike tries to charge the battery. When the current that your battery sucks becomes higher than the current that stator windings can supply, its voltage will start to drop and as result bike will stop. reason is that battery becomes a load instead of a storage. Lead acit batteries should be regularly tested every year. Also should be replaced every two year. Since your bike is 2011 i assume your battery is older than 3 year and probably dead. Try with a new battery if works your issue is solved. If not that means there is a issue with cabling which requires thorough maintenanace because you already checked rectifiers and stator windings.