Flat Battery Puzzle

[TOM VR46]

Thanks for replies. First time ive posted.
Not too sure on age of battery , but had bike about 2 years now. And once again shes been out all night and still sitting at 12.8v. Shes out in all weathers , but I do use cover when parked at work.
It was weired the way she died after bump start. Its seemed like a quick discharge as by time RAC showed up, even hazards were struggling.
Well off to work and see how she goes today.