# Replacment Battery MK3 TTS (2016)



## ArtistX (Nov 20, 2018)

Hi guys,

Does anyone have any info on the correct replacement battery for MK3 TTS (2016)

Do they actually need to be coded in or can I just change it myself?

Audi aren't cheap and charge a lot ontop for fitting/codding battery £265 plus fitting total £448

AA offer fitting at home Bosh from £250/£300 plus £35 coding

Cheers


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## blackvalver (Jan 6, 2020)

AFAIK for proper battery management and longevity it must be coded, you can source the right battery for IRO £150 by shopping around and can probably code it with the cheap version of OBD Eleven (about £50?), perhaps others on the forum can advise on that, useful to have a diagnostics/coding tool anyway.


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## kevin#34 (Jan 8, 2019)

go for the same battery type for technology (agm), a/h (70), dimensions etc, coding it is a must (with VCDS for sure, maybe even OBD11), if the battery hasn't the BEM sticker, just increase the last digit of the current serial number and job is done, more complicate to explain than doing, look for some tutorial on YouTube

you can buy the OEM battery at a much cheaper price outside of Audi dealers net
https://www.amazon.it/dp/B00CEBBBCE/?co ... _lig_dp_it


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## ArtistX (Nov 20, 2018)

Thanks guys


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## macaddict111 (Jun 13, 2018)

Hey man, I'll paste my usual reply below to help you and others understand the point of coding, because I think it's actually a really cool system:

If you've put in an AGM battery, it should be set to fleece. Apparently this is a "bad translation" of the fleece/wool-looking material in AGM batteries and the German word used for them. More importantly, and leading to my next thought, the resting voltage of the battery when set to "fleece" is 12.8, which is exactly what you want for AGM.

Keeping a battery at 14V like in the old days is terrible for batteries, especially newer designs like AGM. Most modern cars (like any modern Audi) have a "accessory mild hybrid" system in that the ECU tries to only run the alternator and recharge if the driver is braking or coasting (aka sort of like regenerative braking). This means the alternator isn't loading the engine when trying to accelerate, which makes things faster and emissions lower. It also means the power needed to restart the engine after start/stop is basically "free" energy gained during braking when you're wasting it anyway.

The important part to maximize this process, is that the ECU needs to know the state of charge of the battery at all times to keep from under or over charging it. This depends on the overall Ah capacity of the battery and its age (hence coding overall capacity and resetting the "age" timer with a new serial number). Additionally, different battery chemistries need to be held at different resting voltages. Normal flooded lead acid like to be held at 12.6 V. AGM needs 12.8 V. If you switch from a flooded cell to an AGM battery and don't change the coding, the new AGM will always be undercharged at 12.6 V, which can in many cases literally half the overall life of the battery. If you treat them correctly (correct resting voltage), AGM can last 2-3X as long as traditional flooded cell.


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## kevin#34 (Jan 8, 2019)

good recap!


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