Audi S4 (B8) Battery change.

[sixpot]

After a few cold mornings last week with most of the electrics switched on, I noticed on the MMI battery meter it had dropped to 60%, having never really been lower than 90% beforehand. Ran around with the car for a few days, with everything switched off, just to monitor the battery, and it never went back over 60%.
It was the original (2009) battery, so I assumed it was on it's way out, and I didn't fancy coming out to the car in the middle of winter for it not to start.
I priced up a few batteries, but aftermarket ones are difficult to code in with VCDS as they don't have a BEM code sticker to update the battery regulator/monitor.
My old original battery was a Varta 110a/h, so I went to TPS to buy a genuine replacement.
The old battery number 8K0 915 105F has been superseded by part number 000915 105DL and costs £193.94 RRP. With my discount it came to £139.64 which is perfectly acceptable for a OEM battery.(these battery's are huge!)
All fitted and coded in no problems, and MMI battery meter is back up to 100%. All ready for winter now!

 

[desertstorm]

I have a 110 AH Varta in my 08 3.0 TDI that is original and will probably be changed shortly. The measuring blocks in the CAN module have calculated the capacity around 46Ah. I will be replacing it with a Varta I5 which is the same battery as the OE one but a lot cheaper.
http://www.ebay.co.uk/itm/Varta-Sil...-Rover-Audi-/271987730444?hash=item3f53bb680c

There was a thread on here recently where the owner of an S4 replaced his battery and just copied the coding from the old battery. And this worked fine.Alternatively some threads seem to say change a digit in the serial number and the car will accept that as a new battery.
I will be trying that as it seems to work OK. And the new battery is the same as the old one.

Karl.

 

[xpoweruk]

I just did my S4 with an aftermarket AGM battery.(same spec)
I used the original code & saved it as a new battery & all is good

 

[rum4mo]

Maybe a silly thread revival, but here goes:-

I replaced the original VW Group 92AHr AGM "Varta made by JCB" with a same spec Bosch AGM which is made by Varta in my February 2011 S4, the only reason that I replaced it was that I reckoned that just over 11 years was enough, no signs of battery failing. The the "actual/available" battery capacity before replacing it was 52AHr, after replacing it the new battery was also showing anywhere between 52 and 60AHr, all I did was to change a single digit of the serial number part of the coding in the CAN Gateway. The battery aging derived from load stayed at 52.0% and the battery aging derived from output went from 86.0% to 88.0% this later set of values was taken after 1000miles of use. The total energy balance went from 9847AHr to 9999AHr and total energy throughput went from 3719AHr to 0AHr when I changed the battery. Also the battery internal resistance (actual) went from 3.8mOhms to 3.4mOhms and the battery internal resistance (standard) stayed at 3.2mOhms, again after replacing the battery and 1000miles of use.

So, why has the battery capacity and the aging not changed, I've seen screen captures of same battery being replaced and values changing significantly quickly after battery replacement - okay in that case the old battery was well used so the internal resistance had become quite high (5.2/4.2) and the battery capacity had dropped to 20AHr - the new battery in that case internal resistance dropped to 3.0/2.6mOhms and the capacity improved to 100AHr, battery aging went from 43.0%/90.0% to 99.0%/118.0%.