Think about
:
your 85 Ah battery is never fully charged. Let's assume batterie is charged about 60 Ah. Next: What power is required to start your engine? I guess when your battery falls below "somewhere" about 30 Ah (?) you can not start your engine.
Sure, all of them are just very rough estimations.
However, even when everything is going to sleep as expected and you're operating a well charged and maintained battery you will get in trouble after about 3 weeks. At least after 4 weeks you can not start your engine anymore.
Summary:
When you tell that your battery is drained within 1 week... I'm not sure if you have a problem.
