Is it time for a new battery? What type and program it to the car?

[Russboy]

Hi all,

For the last year or so i've noticed that the leaving home lights don't work all the time, coupled with having low % battery charge. When I cleared the error code the other day using Carista then they were back again. However didn't last long, so the error code was back straight away.

As usual today I had the following error code when I parked up at work (engine running) at 08:30:

I cleared it, but when I went out a few hours later started the car and it was there again, battery showing at around 10%, same when I left the office this evening:

I do have a dashcam but that runs only on the ignition (via cigarette lighter) as when I switch the car and ignition off it switches to it's own battery (which is rubbish and switches straight off!)

As I say this is not something new, it's been like this for a year. In the summertime I did see it get up to 50% at best, but no more, but we only tend to do short trips, rare we clock more than 10 or 20 miles in a journey. In fact when I have done a 50 miler it still doesn't get any higher. If it were something new I might suspect something else failing but to me it feels like the battery just wont take a full charge, i.e it's had it.

So if I am to get a new battery is there a specific type I should get? Do I need to have it coded to the car and is there a certain procedure on how to do it?

Looking at the battery it seems to say 8K0 915 105F, followed by 520A 110Ah DIN

(Really poor) pics of the battery:

Thanks as always for any help you can give me, Russ

 

[PenttisHSR]

Time for a new battery.
I thought all UK S4's were AGM, but your pic shows a "normal" Battery.

Coding method is detailed in the other thread you posted in

See this post (also non-AGM) .......
https://www.audi-sport.net/xf/threads/audi-s4-b8-battery-change.254212/

 

[Russboy]

So from reading that post you recommend keeping a 12v charge in the system under the bonnet whilst whipping out the old battery then?

If I have to recode then I need to find someone with VCDS I suppose, just more hassle and cost!

 

[Russboy]

When I keyed in the 8K0 915 105 F the dirst website that came up was:

https://www.tayna.co.uk/car-batteries/f/audi-oem/8k0-915-105-f/

Favouring this one:

https://www.tayna.co.uk/car-batteries/exide/eb1100/

Matches the 110Ah but higher at 850A rather than the exisiting 520A, presume that will be ok?

Tried to look on Euro Car Parts, put the reg in and it knows the car but not a single battery listed that matches the 110Ah.

 

[Dippy]

I thought all UK S4's were AGM, but your pic shows a "normal" Battery.

B8.5 with stop/start has AGM.

Matches the 110Ah but higher at 850A rather than the exisiting 520A, presume that will be ok?

The cold crank figure just means that it can source a higher current, however since your car should sink the same current when starting it will make no difference. Getting a higher Ah might be useful for those times when you're waiting in the car with the engine off but interior lights and radio etc are on. Its the physical dimensions that count - you'll need it to fit! Other than that choose a brand that you favour and with the best Ah/price ratio.

I bought a battery for my daughter's Peugeot 107 from Tayna. Great service and excellent packaging.

 

[Russboy]

Brother in law (works at a cars spares place) has secured me a 110Ah 900A (IIRC) battery, perfect fit, Bosch, 5yr warranty for £90.

Old battery out of the car is reading as 12.1v
New battery, in car, not running etc 12.4v
New battery, car running slowly climbs up to 14.1, peaked at 14.3 with some revs.

So it's getting a charge, good.

Got a 60 mile round trip tomorrow so will see what the MMI says as currently (no pun intended) it says only 10% of battery left and it is still triggering that error message on Carista.

I'm hoping the drive improves it, if not I guess this might be the coding to the car people have spoken about? If neither cure it (God I hope they do!!) then I have no idea as getting the same problem on a new battery, so potentially the old battery wasn't duff!

 

[PenttisHSR]

B8.5 with stop/start has AGM.

Myself and xpoweruk have/had B8 manual S4's, both AGM and not stop/start.

AGM is a better (more expensive/longer lasting) battery.
I assume that if you use the correct code (plenty of photos on the net) to copy the "BEM" number, the car will be OK to upgrade to AGM ?

 

[rum4mo]

Myself and xpoweruk have/had B8 manual S4's, both AGM and not stop/start.

AGM is a better (more expensive/longer lasting) battery.
I assume that if you use the correct code (plenty of photos on the net) to copy the "BEM" number, the car will be OK to upgrade to AGM ?

And me!
At over 7.5 years old the AGM battery in my B8 S4 - which is always connected to a CTEK smart charger when the car is in the garage, is still claiming to be in excellent health, if my CTEK battery tester can be believed, and it did prove my older daughter's late 2009 Ibiza's battery was heading down hill prior to my replacing it.

 

[Russboy]

New battery seems to have done the trick.

Did 30 miles to a meeting this morning with a decent run on the M25 and battery level up to 100%, never seen that beefore in the 18 months i've had the car, plus the 03041 Engine Management Active warning has gone and not gone back after the car was parked up for 5 hours, normally back in 5 mins. Will check it again in the morning to see if it's gone for good, if so it doesn't need coding and glad I didn't take up my local garages offer of £80+VAT to code.