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. 

So I thought it might be the battery on it's way out but I got the battery tested and it's 91% health. 

Thanks Hanees,

Who tested the battery, and what parameters did they test?

Kind regards,

Gareth. 

Hi Gareth,

I think he connected some sort of machine to the car which tested the battery health and voltage, I got it tested from a place called Car Spares

Edited March 16, 20242 yr by hanees97

The symptoms you describe are typical (but not restricted to) a failing battery. Ability of your test to declare it totally serviceable in all respects?? 
Do you know how old the battery is? Make may give a clue if you don’t know. 
Kind regards,

Gareth.

Hi Gareth,

I have no idea how old it is but the it was made by Tungstone, I've attached a picture below it does seem old though

I've attached to screenshot's below, I purchased OBD tool to get some readings from the battery. 
 

I put the key into ignition and at the beginning the battery condition was at 78%. Then I switched on the headlights and the heater but left the engine off and it started to get lower and eventually went to 65%. Is the battery just degrading too quickly?

 

The screenshot with it at 14V was with the engine running and I thought that it was a pretty normal voltage reading?

Hello Hanees,

Tungstone would not have been the original battery, but it has been - still is? a bought out brand name from 2009. Having said that it appears ‘the company’ was dissolved in 2019, so your battery could be at least 5 years old, and if so is probably passed its prime. 
Of course Hanees, I cannot claim your symptoms are totally due to an ailing battery, but it wouldn’t surprise me if they were. 
If you do decide to renew it, I’ve bought Exide Premium from Tayna Batteries ( no connection with the company) to good avail in recent times. There are others inc. Battery Megatore, but if you do decide to buy one, it’s worth investing a bit extra in quality. I never buy batteries on price, but by quality - min. 4 year warranty ones at best price. 
Kind regards,

Gareth. 

Hi Gareth,

 I'll probably end up getting the battery changed soon, thanks for the recommendations I'll give those a look. Would halfords be a good bet?

Hello Hanees,

’Halfords as good bet’ - Am I allowed to say no, unless you disrespect your wallet? 
Kind regards,

Gareth. 

Never mind lol, how about euro car parts?

Blinking heck Hanees, - I conclude you really don’t have any respect for your wallet! 
Kind regards,

Gareth. 

Where would you recommend I get the battery from?

Not an Audi owner (my son is) but it definitely seems like your battery is on the way out. I had a 2004 Jaguar S-type which threw out lots of error codes one morning and that was just a failing battery. I always buy my batteries from these guys (see below), they are usually one of the cheapest and most of the time get next day delivery. Regards Colin 

https://www.tayna.co.uk/

See post of 16 hours ago Hanees. Come on catch up! Only joking.