Isn't the idea of the Ctek charger/conditioner that it stays connected all the time while the car is "winterised" or otherwise not being used ? (with the charger's brain figuring out when to come into operation). Since buying my Ctek that's how I have used it, mindful of the instructions in my (Roadster) manual which states: "If the vehicle is left standing for more than 1 week then it is advised that a battery conditioner is used to maintain the battery correctly". So which bits of the car's circuitry cause the battery to run down ? As far as I can tell there's just the clock and the blinking red light on the dash. On another car I use a similar charger and for the past 6 winters I have hooked it up to a standard domestic time switch which activates it for 3 hours each night -- the battery is still absolutely fine and presently shows 14.5 volts (which I don't quite understand, as it is a 12 volt battery).
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Peter
2009 3-litre Roadster "Ivor", royal ivory / green