vinnybuffone

Ok. so i've been scouring the internet, this site included, and i cannot find A Definitive answer on battery replacement. I have found tons of forums talking about this problem, but i need a more concrete answer.
So i have a 2010 A4 Base model. I have noticed that the battery has been slowly losing charge. It takes a little longer to start the car than normal. Then the other day i was waiting for someone with the engine off and i had left the key in the ignition and the lights were on(not thinking). After a bit, a message appeared on the dash saying that the battery was low, that it would charge while it was running. It wouldn't start and i had to go buy some jumper cables. It started fine and i drove it around for the next few hours(an hour on the freeway plus in town driving afterwards)
Well today it wouldn't start. Dead battery. I threw in a XS power cell, ran parallel with the stock battery( how i had it when i had an amp installed) and it fired right up. Obviously the battery has decided to go to battery heaven. With 115,000 miles, i don't blame it.
OK, now the problem i am facing is the "coding" that needs to be done through vcds. I don't have VAG-com and Audi wants $143 for the battery and $195 to install it. $330 bucks for a battery? come on. I have found tons of after market batteries from Bosch to Die Hard and they dont have the BEM code on them. So why would they sell batteries aftermarket if they cannot be coded to the car? A local shop told me that they could install the OEM battery and re code the computer for 95 bucks. Installing a battery is childs play and i cant even see paying someone 95 bucks to do it for me. If i can rebuild my VR6 engine, im sure i can install a battery.
I ran across a forum saying that you don't actually need to recode the computer, that it will just learn the new battery, but Audi tells me different. They say that i will have a lot of problems if i don't and that you cant just change the battery. Ive been wrenching on my own cars for years and have owned everything from a GTI to a RS6.
Can someone please tell me if it is ABSOLUTELY necessary to recode the computer to the new battery and if i can put in an after market battery
? i understand that people like OEM batteries, and i dont blame them for it. But if i can get a battery with more CCA and a better warranty (84 months) than the OEM one, Why not go for it? Audi doesn't make batteries and i don't like paying a premium for the audi stamp on the box the parts come in if i can just get oem parts elsewhere(or better)

fittan

Go ahead and replace it yourself. I have a 2010 A4 and I did it 3 months ago. Bought battery from Autozone (make sure you get the AGM one) and have no problem whatsoever.

There are a lot of misinformation out there. Think about it 14V is 14V. How on earth can the on board computer differentiate between a OEM and an aftermarket battery. Do you see a serial or USB cable anywhere? Those who say otherwise are either 1) have no clue what they are saying or 2) saying because "Ouuu...its an Audi, it is a performance vehicle, the battery need to learn about the optimal fuel to oxygen ratio".

I was similarly frustrated when I decided to change 3 months ago. Here's a link to my thread

https://www.audiworld.com/forums/a4-...2886077/page2/

uberwgn

Vinny, you can get an aftermarket AGM battery and just change the battery's coding by one character using your VCDS cable.


Your car has already activated the BEM preservation system and the car won't know there is a new battery in there 'til you tell it so. The BEM system shut down resources thinking the bad battery is still in there.


B8 A4 Battery Replacement - Coding

uberwgn

Fittan, here's a description of how the Audi system works:


http://www.bannerbatterien.com/banne...echnik_GB3.pdf

vinnybuffone

Thank you for the replies!!! I have read that article before and if what I'm reading is correct, then installing a new battery is fine and the system will learn that there is a new battery insralled right? As long as i get the same Ah battery? A local shop quoted me 45 bucks today to recode the car through vcds. Not a bad price compared to audi. He tells me that: as the battery goes bad, the alternator starts upping its output. He said that if I don't recode the computer, that the car will over charge the new battery resulting in a lower battery life. I don't have a vcds cable to do it myself and they run about $300 on eBay. I might end up just biting the bullet and buying one so I can do more stuff with my car. I asked the guy if I can just buy an aftermarket battery and install it and if he could recode the computer by changing one number, and he said he thinks he can do that. But I don't want to buy an aftermarket battery and have him not be able to recode it. An OEM battery from Audi is only $143. Currently I don't even have the OEM battery installed. I took it out this morning and threw it on a charger and have an XS power cell starting my car right now. So is the verdict to just change it and forget it or to change it and spend the 45 bucks to recode it?

uberwgn

Read the article again.


The car is going to stay in the protected mode for some time. It has to figure out that a new battery was installed. I don't know how long that might take. Weeks? A month? I don't know.


Just track down your local VCDS person. They shouldn't have to charge you anything for something so minor.


BTW, Vinnie, don't buy a crap battery. You'll be replacing it again in no time. I think you'll spend around $160 or so for the correct output AGM.

vinnybuffone

Just wanted to update those who contributed to this post. I installed a new battery and 4 days later some lady hit me and totaled my car. R.I.P A4. So I went and bought an s4. Thanks to everyone here for your help and input