Missus' car battery knacked, so to change it without losing radio settings, I connected an old 7amp/hr battery I took off my Serow 3.5 years ago, it was showing 7v on the mm after all that time sat on the floor. Give it a charge & up to 12v. Sean, you totally killed that battery, error noted for future ref.
I only put the accumate on for 24 hrs once a week or two over winter but always check voltage first with mm, got 3 bikes on the go but they're always 12.6 - 12.8 after a couple of weeks not on charge. Sure the TS battery can't have long now at 6.25 years old.