Battery Coding is Mumbo Jumbo?

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Redd

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I'm a VCDS virgin but I have looked at the existing "battery coding" threads and none of them really hit the mark.

About to replace a 2014 Q5 battery, so it is the more recent battery management system, and I have experience with 12-volt charging systems. Enough to know that traditional automotive systems (plain alternator/regulator) are as one engineer put it "designed to not overcharge a battery" leaving it chronically but slightly undercharged. And the new computer BMS systems...lord only knows what each one does, no one will speak past "trade secret".

But in theory, a modern BMS is programmed for specific battery VOLTAGE, which may be 12.6 to 12.8, and that's a 20% difference in the battery being charged or not. With AGM batteries (mine is) this is pretty important for long battery life, the charging voltage must match the voltage of that particular maker, not just some average number.

Yes, the BMS needs to know the amperage capacity, that's apparent. But unlike a real BMS system, it does not provide for "optimum charging voltage" it only asks for the maker. Every maker has their own chemistry and their own voltage recommendations, so my first thought was "Is the "manufacturer" setting really pulling in a voltage setting?" but this gets more complicated, i.e. since companies like Varta (Germany) license their US operations to companies like JCI, who aren't necessarily using the same chemistry and voltage.

(And yes, I'm waiting for a callback from JCI.)

So is there any reference to just what the BMS changes when you select a different manufacturer? Is it just offering different amperage capacities, with no provision for setting the correct charge voltage? (The actual bulk charge can be somewhat loosely set, but for an AGM the best life comes when charging is stopped rather precisely, and the battery kept to a 100% charge, not just the 90-95% that a wet lead battery might be happy with.)

Any real technical information out there? I can't seem to find a hint of it. In deep cycle, solar, backup power, all the major battery applications, this is old hat and published. But Audi....ah, not quite.
 
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Uwe

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I haven't seen anything more detailed than what's already out there.

IMO, the most important thing a BMS does in the car is to monitor the battery's State-Of-Charge and ask other systems to shed loads if the SOC gets too low. It also keeps track of total energy throughput, which is something of an indication of the battery's health.

-Uwe-
 
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DrPeter

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Redd

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Thank you, dpeter, I will read that tonight.

Uwe-
How kind of you to chose an image so reflective of my car. We call him Herr Professor Doktor Strangelove, a slightly eccentric German genius on wheels. But no BMS can monitor state of charge correctly, unless it knows what the full (100%) SOC voltage is. So, either Audi is faking it, or they are somewhere tying in the battery maker/model to a specification they have obtained for it.
Seeing how quickly my OEM battery was consumed...I am reminded of an English Queen's words: "We are not amused."

Hmmm. Dpeter? Erwin just allowed me to register, but it never prompted me to create a password, and of course it does not recognize the user name that was just put in either. After I clicked on 'register' I got no confirmation, not even the usual "we'll email you" note. Am I missing something here?
 
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Uwe

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But no BMS can monitor state of charge correctly, unless it knows what the full (100%) SOC voltage is.
It knows what the Ah rating of the battery is. It knows exactly how many Ah have flowed in and out. The newer BMS systems also know something about the chemistry of the battery (AGM vs. flooded, etc). Some might argue this is better than just some arbitrary voltage, which really only reflects SOC accurately under open-circuit conditions at a specific temperature.

-Uwe-
 
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All Battery and Energy Management Systems (BEM - that's the official term, BMS is not used in the VAG world) have known the battery type. The upper class Audi BEM's got the info via the part number, lower class and recent BEM's had a direct info about the type either via coding or a separate adaptation channel. Keep in mind that the systems are designed for OE-Batteries, which means the vehicle manufacturer has the supplier build batteries matching the vehicle manufacturers specifications and not the other way around.

As far as battery coding goes, if you are using a true OE-battery there should not be a problem in the first place (all data except the serial number should match the previous battery in almost all cases). However, if you are using an aftermarket battery, my recommendation is to enter the proper data (type, Ah and supplier). If your supplier is not listed, check if they are just a reseller (for example Bosch branded batteries are often made by Varta) and if nothing helps, some modules will accept XXX as a supplier or just go with Varta. The supplier bit is (if my recollection is correct!) only relevant for warranty issues and has no functional influence on the characteristic curves. As far as over-charging goes, on modern Start/Stop equipped vehicles, the BEM only charges the battery up to 80-85% to leave room for recuperation in order to put the generator in idle and to save fuel in the process.

Fun fact: A few years back, there were (independent) tests in the German market with OE and aftermarket batteries. A specific case was very interesting, the VW-branded Varta had different/better results than an aftermarket Varta - both with the same ratings (Ah, Cold Start etc.).
 
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Jack@European_Parts

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Does anyone else see that Varta batteries seem to mostly die early in the USA & long before their rated useful life, why is that?
 
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PetrolDave

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Does anyone else see that Varta batteries seem to mostly die early in the USA & long before their rated useful life, why is that?
Must be a USA thing - I fitted a Varta battery in 2010 and only just had to replace it 8 years later.
 
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Sebastian

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We have seen Varta batches fail, Banner batches fail and the same applies pretty much all other brands as well (as far as the German/European market goes) - however, those were just batches and it happened within a defined timeline and got addressed down the road. Generally claiming a specific supplier is bad is likely not constructive. As stated by @Redd, a certain brand uses different lower tier suppliers and production plants...
 
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I think the battery in our BMW E39 was a Varta (OEM, BMW branded, installed in Singapore)... it only lasted a few days over 13 years :D Of course it was a warranty replacement, after the first one only lasted a touch under 3 :cry:

According to local forums***, none of the aftermarket batteries peform like the OEM, so I guess they're not the same as the originals, even if Varta branded.

*** everything you read on a forum, anywhere, is correct, right???? :D
 
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Uwe-
A good point, that's what a coulomb counter does. However, counting the number of amps in and out is only one part of knowing SOC. You actually need to count watts (volts and amps) in and out. And, you MUST know when the battery is at 100% SOC to being with. You cannot assume a "new" battery is at 100% SOC, they often have been on the shelf for three or four months and may be at 90% SOC when they are "new". Proper installation requires that the SOC be calibrated and confirmed, at installation and from time to time, as there will be other factors such as Peukert's constant, which varies with temperature, charging rate, and battery age, but determines what percent of the power supplied actually charges the battery as opposed to be consumed in the charging process. Simply knowing the ###AH rating on a battery was good enough in 1970...it is obsolete now for maybe 20 years in the consumer market, longer among the engineers.

Sebastian-
Since VW doesn't sign my paychecks, I will still call a BMS a BMS, even if they prefer BEM. Call it a translation problem.(G) I'm not surprised that VW-OEM Varta batteries would differ from retail Varta batteries. I would expect that the Varta batteries in the US are ALL actually US made by JCI, and not by Varta at all, so the US Varta batteries may or may not match JCI's own specs, or Varta-Germany specs. JCI probably has their own process and materials, whether they have contracted with Varta to do things differently, or licensed something...neither one of them will ever tell us. You'd have to do lab tear-downs and alloy analysis to find out.

Jack-
I know the Varta US battery that the dealer put in my car as a warranty replacement at 14 months died REAL early, 3 years of tender care including a light solar float charge to ensure the battery always got something extra. A similar flat-plate AGM from another manufacturer gave me 8 years of life, although that was well below 12v at that point, and this last one is still 12.17, useful just questionable. (The dealer was certain that was low enough to be causing bogus error messages, so I'm replacing it as a reality check.) JCI are generally considered a top-quality vendor, unless the Varta contract calls for real junk...doesn't seem right.

NZ-
The problem is, batteries are mainly LEAD and lead is damned dense, making it expensive to ship for any distance. So if you are a car maker and you order them by rail carload...you can have a good time getting bids. For everyone else, the options are more limited. In the US we have three major battery makers (Interstate, EastPenn/Deka, and JCI I believe) and each has a limited number of plants. So when a large customer asks for bids for "OEM" replacement batteries for warranty and other sales, they take bids. Even the national chains (WalMart, Sam's Club, Costco) will buy batteries from one vendor in the Northeast, and another in the Southwest, three thousand miles apart. You just can't economically ship batteries that far. So each one has their own contract specs. Maybe I want 50,000 Group24 batteries that I can sell for $49.95, and the vendor normally targets them at $54.99. The vendor can make an "identical" battery for me, but use less highly refined lead in the plates. Or maybe make the plates 4mm shorter, leaving more empty space in the bottom of the case (and calling that an advantage, so sulphites don't short out the plates.)
To the buyer--they are identical batteries with identical labels slapped on them. Getting an exact weight is one way to guess. Peeling back the side label and seeing the manufacturer code is another way.
Otherwise...this is why the consumer magazines do battery tests every few years. You really need to get technical and tear them down to find out what the game is.

With deep cycle batteries there seem to be fewer games. The makers sell mostly under their own real names, and the users have no use for the batteries without real technical information, so the makers provide it. Right down to temperature compensated voltages for bulk and float charging.
 
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DrPeter-
"Generally Self-Study Programs can be purchased from Audi's erWin website, https://erwin.audiusa.com/erwin/show...ticleId=170512"
Before I go buying "books" sight unseen, can you give me any idea of the content? Or are they just going to tell me marketing talk, location of modules, but nothing at all about actual coding and details of operation? If they're going to say "These are the modules, how to test them, how to replace them" then that's not what I'm looking for.
 
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Before I go buying "books" sight unseen, can you give me any idea of the content? Or are they just going to tell me marketing talk, location of modules, but nothing at all about actual coding and details of operation? If they're going to say "These are the modules, how to test them, how to replace them" then that's not what I'm looking for.
Self-Study programs are training guides intended introduce new models, new engines, new transmissions, and other new systems to dealer technicians. The usually cover theory of operation, but are not repair manuals, and certainly don't have coding info in them.

-Uwe-
 
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Uwe?
Could you perhaps enlighten us as to what all of the different voltages that the VCDS screens show really are? Where they are mentioned, or any fuller translation of what they are supposed to be?
When I finally (and almost accidentally) found a set of "real" 95A AGM BEM numbers, I still see too many things that just don't have any meaning to me. For instance, Group 18 "Battery Voltage" apparently is a voltage measured at the battery--but while it is under charge?

Is there any more comprehensive reading available as to what these groups and numbers actually are supposed to show? Or whether inputting a BEM actually is programming the charging system to any real parameters?
 
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Uwe

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Uwe?
Could you perhaps enlighten us as to what all of the different voltages that the VCDS screens show really are? Where they are mentioned, or any fuller translation of what they are supposed to be?
Off the top of my head, at 11:00pm on a Saturday night, for a car I've never had, no, sorry.

-Uwe-
 
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Redd

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Well, I hadn't meant "instantly" nor even particularly for this model. I would think the battery management system was basically the same module across a larger number of cars from the same production years, not custom to the one model.

A cynic suggested to me that it is all suspiciously like a dog and pony show. Lots of numbers and labels, yes, but no sign that putting in a correct BEM actually changes the behavior of the system. Hinting that the only true purpose of the BEM is restraint of competition--claiming that it is necessary to have Audi install Audi approved batteries when in fact, it is not. But of course, I'm sure AudiAG could quickly disprove that. Of course.
 
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Uwe

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There are many things that car manufacturers do that serve a dual purpose; they really do make things better in some way (for example a BEM makes it much more likely that you'll be able to start your car despite having left stuff on that you shouldn't have left on, or an immobilizer that makes it more difficult to steal cars), while at the same time driving people back to the dealership for certain parts and services (e.g. a battery with a proper BEM code, or acquiring a replacement key and getting matched to the car).

-Uwe-
 
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