ltooz_a6_a8_q7

Thanks all, at least when someone doesn't have a VCDS, he/she can replace the battery without worrying about buying a $349 just to change a battery. I'll re-code the battery with my VCDS, which I hate to use. Does anyone has a link of the coding handy?

Louis

Jack88

Here you go! This should do it.

Battery recoding

jlbell

I bought an Audi battery for $220 which was way less than I expected, so not bad. However, when I asked them if they could install it (granted I have VCDS and the know how, but was worried about the 2 year warranty should the battery go bad) they quoted me another $300 just for install and coding. I nearly choked on my own spit and walked out with the battery, after discussing installing and coding it myself with regard to the warranty. Turns out they don't mind as along as you update the serial number in the coding. The only issue I had was with the BMS not recognizing the revision letter. So I changed the base part number but kept the original revision letter, while also updating the serial number and the BMS accepted it with no issue. Another thing to note is once I successfully installed the battery, I happen to stop by a friend of mines shop, he is a master BMW mechanic. We went on our usual chatting, then I remembered to mention to him I changed the battery, and Audi tried to charge me another arm and leg to install and code the battery. He sympathized but then went on to explain the importance of coding the battery. Turns out, for BMW cars that use similar BMS, it is entirely essential to update the coding for the sake of the battery and alternator. He then went on to tell me a story when a 2005-2008 BMW 7 series owner decided to ignore the fact it needed to be coded and changed the battery. A few weeks later he was not only replacing the battery but also the alternator. He said it was due to the fact that a new battery doesn't need to be charged at the maximum capacity of the alternator, which it had learned to do due to an aging battery that was replaced. So BMW systems not only monitor the health and voltage of the battery but can also limit the charging voltage. Interesting, it scared me enough to be glad I put in the few extra minutes to punch a few numbers into a computer. Because if BMW uses such technology I can picture Audi doing the same. P.S. my father couldn't contain his laughter and disgust when I told him the labor involved with Audi changing the battery, plus the fact that a computer was needed just to change the battery. It was essentially the same reaction when I let him know about changing the rear brakes and the EPB. He has said to me that he is glad I understand computer as he would have just put a stick of dynamite under the hood to claim insurance vs paying for the excessively high cost of labor of these cars to do simple maintenance and services.

JulianHicks

1. $220 for an Audi battery? If that's an Audi badged one that may be right but any other reputable 110Ah battery is suitable and they can be acqured for about $100 in the UK.

2. Did you really mean another $300 or a total of $300 - $80 more? Let me see: disconnect battery terminals, remove battery, replace with new battery, reconnect terminals. That's 10 minutes. Plug in VCDS or equivalent, recode battery manager. Another 10 mins. I make that $240 per hour to change and code batteries in some parts of the US

3. The Audi BEM does what the BMW one does. The Audi alternators have variable output and the BEM tells it what voltage to select for charging. After you start the car, the alternator's output voltage is high to recharge the battery and as the BEM detects the capacity increasing, the voltage reduces.

Julian

MP4.2+6.0

BMW said, let's see...twirl three times, stick your finger who knows where, say abacadabera, stand on one foot while walking backwards counting "down" from 100, click your heels if you want to drive to Kansas, and oh, cough up $$$$. Don't ever "count up" or the Soylent Green machine turns you to powder just for fun. Oops.

Yep, the Mini S (aka BMW captive brand) I had employed the same system. I followed all those steps except the $300 one. Hmmm, didn't buy the gazzillion dollar software BMW uses for VCDS wannabe equivalent use that is straight out of the assembly language stone age. But since it's a Mini, they get modded to Hell anyway, so who's to know, right?

Oh, and I bought the battery from Home Depot. Literally! Interesting experience when I came to the Returns desk with the old one for the core charge. The clerk didn't a. know what a car battery was, and b. had no idea what a core charge was or where to find it in the register computer screens. An Exide, since when I peeled back the Mini (err, BMW) label, it sure enough said Exide. Mini/BMW are too cheap to even have Exide put only the Mini/BMW label on at the end of the line. Back to Home Depot: Mini, no worries, 72 F100, check, 81 Fiesta, got it, Chevy stepside, yep. You see them near the exit doors at Home Depot. How they all come from the same three battery suppliers pretty much... Funny thing, when the Mini got totaled 3 years later, it had a lot more to do with the impact than the battery. In fact, responders cut the cable to it to be sure it was dead. That seemed to have killed it a lot more than the BEM.

Think about it. Unless the programmers literally put a line in saying only "count down" and never "count up," it will gradually learn the new battery parameters again. Too busy programming TDI mischief to bother trying a new angle to maximize battery sales. BMW programmers are probably amateurs compared to the TDI pros though...the ones now hiding out in the Vaterland without the extradition treaty as it turns out to avoid the Feds w/ the cuffs. But the BMW guys do have some pretty good sales lines. I heard they sell Soylent nutrients on the side...

jlbell

I am not lying. It would have been a total of $500 for a new battery. $200 for the battery after the $20 core charge and another $300 just to install the battery and code it. I literally couldn't believe it when they told me!

ltooz_a6_a8_q7

After reading about all views of different makes of Battery and I decided Walmart EverStart Maxx H8 was the best choice for my car at this moment. I haven't done the VCDS. Everything seems to work fine.
I do know something about charging system since I'm in the field. I don't believe all the assumptions about the charging system can reduce the charging current (capacity) to adapt to current battery condition because they can't check dynamically.

How to test a battery to see if it's good? - put a load and see the battery drops in voltage and how long does it hold the voltage.
The charging system can only sense the voltage drops with a fixed load and charge it accordingly.
All charging systems will turn off when the battery is full providing second source is running like your electrical devices: smart phones.
In order to limit the charging current, there must be dynamic resistance in series which can be in the form of Potentiometers. Digital potentiometers only for microcontrollers and not really for high current and voltages. I don't see this is viable for any car application especially in 2006. So if BMW or Audi said that you can burn up your alternator or new battery if you don't tell the system that the new battery is installed is BS (NOT bachelor of science). Unless they have a "secret ingredient".
Alternator is running and producing the same current and voltage by regulator all the time - when the battery is full or dead, you're running on alternator regulator and current if your alternator is good.
If there is a dynamic analog potentiometer which I don't know about, it wouldn't last with all these exercises with changing current all the time and whoever design this system is NOT economically sound for any reason.

Remember ohms law V(voltage)=I(current)xR(resistance). Voltage is the same, then to change current, resistance must change accordingly.

Cheers,

Louis

dvs_dave

The energy management control unit J644 informs the alternator of the specified alternator voltage required via a data wire (bit-synchronous interface). This voltage is then set by the alternator. The battery manager (function module 1) determines the specified value from battery temperature and battery charge. The specified value established is then transferred in the control unit to the dynamic management (function module 3), which relays the value to the alternator.

So, not resetting the energy management system when replacing the battery won't immediately cause obvious problems, but because of the learned old battery performance, it's very likely that you're risking damaging and shortening life of the new battery by overcharging it, until it learns the new battery's performance characteristics.

Take the time to read the SSP's, they're very interesting and explain how all the systems work, and why.

ltooz_a6_a8_q7

Just like you said, the battery management system is quite impressive, it can disconnect all power hogging loads when it needs to save power. It's a great system but it has no control over the charging the battery. Just like you said, it's smart enough to sense the battery health and act accordingly. This is contradicting to me is when it requires a new battery need to be encoded... Since it's so smart, it should just read the new battery state of HEALTH with all its sensing functions. If I was in the design review, I would question this.

"Battery replacement
On battery replacement, the new battery must be adapted by way of the diagnosis tester. The menu item "Battery manager encoding" is provided in the assisted fault- finding routine in the list of systems with self- diagnosis capability in the battery manager. The battery serial number has to be entered for encoding. This is marked on the battery."
SSP287_068

The battery I bought only has 3 years warranty and $140 including tax - I'll just let it be without VCDS coding to see how long it will last. I just don't agree when these technicians claim the alternator and battery will burn up if not re-code in the system.

Cheers,

Louis

haggisuk

The bem records energy out vs energy into the battery. So if it's recorded that your old battery is depleted and you then go fitting a new battery as far as the car is concerned it's still flat. So will try to replace the energy out.

As mentioned in the ssp the alternator is commanded to charge the battery according to state of charge and also shedding loads until it thinks the battery is recharged to a sufficient level.

there is an in depth thread over at Ross tech forum about the bem and the beta software allows you to see the logs from the bem as the dealer can with the dealer tool.

Audi and any other manufacturer using a similar bem system didn't design it for the fun of it, these cars have high demands on the cars battery and without the bem I believe we would be replacing batteries far more often with out the bem looking after it for us.