So about 6/7 months into ownership I've got a really weird issue with my A3 8V. About 30-40mins into driving, my stop/start and say Automatic Stop/Start System Fault: Function Not Available, my heater fan speed gets reduced and doesn't work at full fan speed and the engine revs at 1100rpm when idle. I've only started to experience these faults when the car was sat for 6 days and it popped up with a message saying Low Battery: Battery will charge during drive but since then I've covered 400 miles which has been motorway mileage. It's got a 12v cigarette lighter splitter which has a dashcam and footwell lights connected, I don't know if that could be causing an issue but any help or advice would be appreciated. 

Hello Hanees,

Thanks for joining, and welcome. 
From what you describe, I think you are right in suspecting this may be due to a below par battery, and if it were mine, I would be wanting to confirm or refute that possibility, as my first course of action. These car depend heavily on an efficient battery.

Take the car on at least a 10 mile run to allow it to have some charging after starting, then drive to a Halfords store and ask them to test the battery efficiency for you. They will test a number of parameters - under load - and give you an overall % efficiency figure. 
Depending on how quickly you need this sorted, it would probably be best to come back to us rather than getting a new one fitted at Halfords there and then, so just come back to us first if you want to. 
Kind regards,

Gareth.

Hello Hanees,

Did you get any further with this after? 

Hi Gareth,

Might sound a bit weird but the car kind of just fixed itself. I've only occasionally had the issue of it popping up with low battery but it's been working fine since.