Left mine at Heathrow Long Stay for just under four weeks and the battery was completely flat when I returned. Not good news at 7.00am on a cold drizzly morning after a long haul flight. Am I being naive in thinking it should hold charge longer than that? I do plenty of driving to keep it charged, including a 100 mile journey to get to Heathrow in the first place. Anyone had a similar experience? I've just bought a solar powered battery maintainer in the hope of avoiding future problems!