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Thread: Battery Coding is Mumbo Jumbo?

  1. #11
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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 Simply knowing the ###AH rating on a battery was good enough in 1970...it is obsolete now for maybe 20 years in the consumer market, longer among the engineers.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.

  2. #12
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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.

  3. #13
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by Redd View Post
    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-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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  5. #14
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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?

  6. #15
    Benevolent Dictator Uwe's Avatar
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    Quote Originally Posted by Redd View Post
    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-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  7. #16
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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.

  8. #17
    Benevolent Dictator Uwe's Avatar
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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-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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