Battery drain - wouldn't start after a day

Just a quick question with regards to a problem I encountered this morning.



I went to start my TF; the electrics turned on fine pre-ignition, however when I turned the key all I heard was a clicking sound.

Jump starting it seemed to start the car.



Couple of things: last week a couple of times the battery sounded a bit flat but still started the car. The rest of the times I've run the car it has started fine with what sounds like a full charge. My journey is usually about 20 miles.



Ever since I've had the car when I've activated something electric (e.g. turning the fan on, window activation, going from side to dipped/full beam) it has tended to briefly dim the instrument lights before going back to full brightness.



Would this indicate a bad earth? Would this cause battery drain?





Thanks for your help :)

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