Battery Stamina - How long without use?

[Randyjim]

My ZT190 was left stood for about 3 weeks recently and when I came back to it the battery was flat. Does this seem normal for residual drain from security systems, or does it indicate the battery is on its way out?

It started fine with a jump from mum's Golf, and had enough juice in it again for a restart after a fuel stop about 30 miles later. Its normally used as my daily and I've never had battery issues before so I don't think it's an immediate issue, but perhaps one to plan for.