Why is everybody intent on selling me a ridiculous priced battery for this car?

[Bendelaurence]

Everywhere I look everybody is recommending and AGM start stop battery at stupid prices.

Take Yuasa for example. They Recommend YBX9020 £220 street price

Capacity at 20-hour Rate (Ah) 105
Cold Cranking Performance (Amps) EN1 950

This car does not have start stop. So I see no reason why this battery wouldn't work just as well. YBX5020 - £129 street price

Capacity at 20-hour Rate (Ah) 110
Cold Cranking Performance (Amps) EN1 950

Same deal with most other manufacturers.

RS4 seems to equal "over space it and take his money'.

Am I missing something?

[Nige_RS4]

Have you tried tayna.co.uk? They seem to offer the best prices around, even better than all the usual places with their up to 60% off codes GSF, ECP etc.

Use code FACEBOOK45 for a bit of a discount too.

Can't answer if you still need an AGM battery, though I suspect not if you don't have stop start fitted.

[johnnydog]

The battery should be an AGM battery, and a replacement needs to be programmed to the car. It's not just a case of fitting a new battery and off you go. If a replacement isn't programmed to the car, some of the electrical systems will not function correctly apparently. I was quoted a discounted price down from £250 to £150 by Audi for the battery, but it required an hour's labour on top to fit and reprogram it. I was lucky as the car at the time was still under the manufacturers extended 5 year warranty so when this was verified, the replacement battery and reprogramming was covered by the warranty.
The subject of battery replacement was referred to a while back in the topic 'Muliple dash warning lights' if you want more info.

[Rusty Racer]

Fairly sure my original battery isn’t AGM.
While it would be logical to fit one as it’s in the boot I believe mine is a lead acid version from the factory.
I have purchased a number of different ones from tayna who also guide you to a pb battery as we don’t have stop start. Check out what’s under the boot floor!

[Grandadg90]

My original wasn't an AGM, so I replaced it with a Varta, same spec for circa £130.

[Bendelaurence]

Got one on the way from Ford £99, with OBDeleven on hand to code.

I’ll let you know details and problems encountered later if any. Ford say the battery is right for the car. So if it doesn’t work, it’s going back.

[CusterDome]

Thanks for the thread Bendelaurence, let us know how you get on.
I'll admit I'd never heard of an AGM battery until just a few weeks ago, when the thought of my car being underused during these lockdowns made me wonder how the battery would cope.
From what I (ok, Google...) can find, it sounds like there's a few advantages in either staying with an AGM battery, or switching to one when your battery needs replacing. They cost more but have a longer life, so probably cheaper in the long run, there's no chance of a leak even if damaged and they require pretty much zero maintenance. Some sites say they are more powerful/efficient (does that mean they could be smaller and lighter for the same output?), but I couldn't find any numbers or direct comparisons with a LA battery. So it sort of sounds like it's probably worth an upgrade when the time comes?
What was your reasoning behind going the LA route?

[Bendelaurence]

So it turns out my £99 ford battery was an AGM 850 95 (slightly different to the original which was AGM 850 105 but still within range of compatible batteries). Either ford made a mistake, oh there are some really good deals out there to be found.

On to coding. This is where it got a bit complicated as there is a lot to conflicting info out there. But I got to the bottom of it (for my car anyway)

1. Does it actually need coding?

The short answer is yes. If your ecu has not registered the old battery a 'bad', a new battery will continue to work with no errors. However, the ecu will think its the same 7 year old battery and charge it accordingly. I read a few people saying that the ecu will figure it out eventually, which may be the case but I choose to do it the right way rather than plugging in the scanner every few days to check the stats were slowly reseting to 100%

2. What info do you need to code the new battery.

Well there are many posts pointing to the user entering a new serial number, capacity, manufacturer and battery technology. However, when you connect our RS4 B8's to ODBeleven this page doesn't exist. I did some digging, and it turns out this page is specific to a VAG charger module used across most cars, but evidently not ours.

The page I found simply asked for a BEM code which is comprised of model number, manufacturer and serial number. From what I gather all our car needs to know is that a new battery has been installed so that it can treat it as a new battery and modify its management slowly as the battery gets older based on its own battery test and logs. I could be wrong, but I dont think it looks up a specific battery spec based on this number to base its battery management on.

So! If you get an OE battery or non-OE battery with a BEM code, you simply type in the new BEM code and everything resets. If you get a non-OE battery with no BEM code but the correct spec (like me) you just need to change one digit in the serial number and everything resets.

Where I would be careful, is trying to use a non-AGM battery. AGM batteries require a different charging strategy, and I cannot find a way to specify battery technology in ODBeleven on my car. So, either the charging module can detect battery tech, which I can't find any info on. Or it just wants an AGM battery, which is why every manufacturer recommends only AGM for our car.

So there you go. All my live data looks good. Battery is now showing an SOC of 100% rather than the topped out value of 65% on the old battery. So fingers crossed we should be good for a few years.

[Yanto]

Guys....dumb question....

My battery seems to have just packed up out the blue. Car has never been sat undriven longer than 3-4 days at a time. 15 plate car in AUC warranty until July 2021. Can I just use Audi breakdown to sort this out ? Battery coding is a new one on me and I just cant be arsed with the faff...

I know I can check the warranty docs, but on the off chance anyone in my position has experienced similar, would appreciate any experience. Thx.

[Bendelaurence]

I can’t see why an Audi extended warrenty wouldn’t cover this. Also if it’s completly out of the blue with no prior warning signs, it’s worth considering the alternator and charging module.

If you’ve got a warrenty, get it in to them mate. They’ll check everything and get it fixed.

[Yanto]

I can’t see why an Audi extended warrenty wouldn’t cover this. Also if it’s completly out of the blue with no prior warning signs, it’s worth considering the alternator and charging module.

If you’ve got a warrenty, get it in to them mate. They’ll check everything and get it fixed.

Cheers - I’ll give them a bell tmrw.

[johnnydog]

If you go back to one of my previous posts on this topic, my car had the 5 year manufacturers warranty purchased when the car was new, and Audi covered the replacement battery and reprogramming under this warranty. I have since taken out the all component warranty following on from the 5 year cover, but the cover isn't quite as comprehensive. What is covered is in the small print which isn't at hand at this moment unfortunately.

[Yanto]

If you go back to one of my previous posts on this topic, my car had the 5 year manufacturers warranty purchased when the car was new, and Audi covered the replacement battery and reprogramming under this warranty. I have since taken out the all component warranty following on from the 5 year cover, but the cover isn't quite as comprehensive. What is covered is in the small print which isn't at hand at this moment unfortunately.

Cheers - I’ll give them a shout.I bought as an approved Audi in July ‘19 with a 2yr warranty so it’s likely the second type you mention above