Hi there,
I have a 2007 2l tdi A5. I have had it 3 years and every winter without fail, the battery drains power overnight. I have replaced the battery twice, the current battery is only 8 months old and the highest amp one available in Halfords so i can't believe it's actually the battery that's the issue. Also after a spin it works fine as it does in the summer so i think alternator problem unlikely?
Attaching a trickle charger on very cold nights works but costs a fortune in electric bills. I even tried covering the engine and battery with blankets which bizarrely worked. It is so annoying as it seems there must be something electrical causing the battery to lose charge which happens quicker when it's cold. No interior lights are on and i always turn the radio/heaters off. On very cold nights, it can drain in about 9 hours.
Any thoughts and suggestions would be well received.
Thanks