Redd

Didn't get a chance to talk to AAuto corporate. The stores say "we don't program" all they do is physically bolt it in. Yes, we both know they NEED to program if they are going to "install" an Audi battery, but they don't program.

I have never replaced a battery same/same unless it was my own to start with. Always gone bigger, to get extra safety margin, extra life, extra protection from "Is that dome light still on?" days.

From rereading the VCDS battery instructions and rewatching their YouTube, there's apparently at least two different ways to code this battery. I may have stumbled into the "wrong" menu, or the "right" menu may have been obsoleted...I need to go back and literally compare screens and notes to make sure of whether I can "simply" Pick JCB as the vendor (we call it JCI, they call it JCB) or Varta, and then select the capacity 95A. If VCDS will allow me to enter those manually, that should make....Wait a minute now, you are NOT my uncle! Are you? (G)

Any idea why VCDS will show voltage at "Terminal 15" vs "Terminal 30" as being different? What those "terminal" locations are?
I'm impressed to see the BMS apparently also tries to guess battery temperature from the ambient temperature, and accommodates the charge for it. It sounds like quite a sophisticated system, although getting only three years out of the stock battery says that still isn't quite good enough.

Bob Petruska

MurrayA4

Yes Audi is saying to the consumer and most garages that you better leave this issue alone and bring it to your fine Audi dealer who will sort it out for you using their battery. Redd I picked this up and it may clarify this very fuzzy issue.
Self-teaching system In the case of an elderly battery, the vehicle system stores the term “defect battery”. Accordingly, if a new battery is installed without the entry of a BEM code, initially the vehicle does not recognise the presence of a replacement. Therefore, the energy management system must either be informed of the new battery status via a BEM code input, or learn the new battery status. The more trigger events (impulses, signals, e.g. starts, cold starts) experienced by the battery, the faster this process is completed. The vehicle computer then successively releases the previously limited systems, e.g. the full performance of the air conditioning system.
No safety risk If a high-quality battery is installed without the input of a BEM code, this neither constitutes a safety risk, nor a possible danger of damage to the vehicle electronics or other components.
Believe this info comes from a British company not a Russian one.Hope it helps.I enjoyed the days of having to check my battery fluid a couple of times a year.Could often give you a heads-up of an oncoming problem and the damn things lasted just as long as modern AGM's .The major downside was you had to maintain the terminals because corrosion was a given after a couple of years.

Bob Petruska

Murray, the problem is that no one, and I mean no one, has ever told us on the net if a BEM code has intelligence to tell a power management system what battery Ah capacity, CCA's, internal resistance, charging profile, etc. is installed. The consensus on the net that the BEM code is just a dumb code to allow one to read what battery manufacturer and model is installed and does nothing else. That being the case the Ah capacity and charging profile that is programmed into the BMS from the factory isn't going to change. Thus if Redd replaces a 75 Ah battery with an 95 Ah battery, and he leaves the car sit a long time, the BMS is going to shutdown select systems over time based upon a 75 Ah battery than the 95 Ah he has now installed. Most likely he will be able to start a run down Q5 battery at a longer discharge time with the 20 Ah reserve, as that is the end goal of the of the BMS to allow the car to start after sitting idle a long time.

The best and easiest thing to do is buy a new battery that has the same specs as the old factory OEM battery and just change the last digit in the old BEM code that is stored in the BMS with a VCDS and you are good to go without wondering if the BMS will work correctly with the new battery.

As for Audi controlling everything, making you go t the dealer. My relative just told me his friend hit a very deep pot hole and needed a new GM steering assembly. The GM dealer went to a salvage yard and got an exact replacement, installed it and it said it needed new coding to work with the vehicle, the dealer tried to recode it and failed, they called GM tech support. Tech support stated that you can no longer just recode a used part that wasn't on the vehicle to use it, you must purchase a brand new one and recode that part, and that's the only way!!!!

Redd

Bob-
You know, just last week I promised my parole officer that I wouldn't take any hostages for the next 90 days, I would really try to go straight this year. But, Ingolstadt is out of her jurisdiction so perhaps she won't mind if I enquire of the Audi engineers.

Honestly, a BMS *must* know the capacity of an AGM battery in order to charge it properly. Improper charging results in premature death, which, gee...I have noticed. So it is entirely possible that the Audi BMS with all of the technical data shown in the VCDS details is dumb and it is ignoring this. You may be right.

OTOH I think I have now the BEM for the Varta/DE 95Ah battery, and using that may produce results close enough for horseshoes or government service. I plan to record the current code (of course) then flash the Varta/95 BEM, give it a week or so to let the system readjust, and see how that goes. I'm wondering, since "the same" BMS may be dealing with different generator sizes, one or two batteries, and diesel/gas/autostart batteries as well, if they'd really use a "one size fits all" or more simply, provide for recoding the same BMS for the different situations.

If you get really bored...can you see if the battery management system (which should be a separate computer/part number?) is spec'd as the SAME part for both single and dual battery, and all three engine choices? If it is, then we can be reasonably sure it is responding to programming. I *suspect* the generator for the dual-battery option is a larger one, part of a package, but the same BMS might be used. (And no, I didn't go under the trim looking to see if there are cables, etc. there in a big empty space. I suspect those would only be part of an extra harness installed with that package.)

So, who wants schnitzel? Who is coming to Ingolstadt, and willing to either take notes or cook for the rest of us while we get those answers?

Bob Petruska

1. Batteries are not charged regarding what capacity it has. Otherwise a battery charger, such as C-TEK, would need to be programmed to do so. Charging is base on being a FB or AGM, and then the voltage profile is measured thought the course of charging to determine when the battery if fully charged.

2. Right now it looks like a BEM code means nothing to the BMS, except that a new battery was installed. With the Q5 it most likely looks like a 75 Ah and AGM charging profile was coded at the factory and not changeable. Your 95 Ah battery is just going to have the built in 20 Ah reserve.

3. I think that you are good to go with whatever BEM code that you use.

It sure would be nice for some battery engineers (Varta, Bosch, etc.) that most likely read this forum would tell us if the BEM code has intelligence or not, and does it program a BMS accordingly, but this is just wishful thinking!!!!

Redd

"1. Batteries are not charged regarding what capacity it has."
Yah, in theory. In old theory, of "two stage" and "three stage" dumb chargers. There are other ways of doing things now, rather than just applying voltage. The charging current may be limited, base on the battery capacity, and especially with AGM, within certain limits the charging current is more important that the charging voltage. For instance, some systems measure the battery voltage, compare that to the specific voltage for that battery (which varies by maker and must be programmed in, since pure lead and each differing alloy all have different "full" voltages) and then proceed to dump in the maximum AMPERAGE while only leading the battery voltage by ~0.4 volts. So a "12" volt battery may be charged at 12.4 volts, while a "12.4" volt battery (40% higher SOC) gets charged at 12.8 volts. and every minute of so, the charger takes another look at the battery, and continues adjusting the charge voltage to match the battery, until it has pumped in enough amps to match the programmed amp capacity of the battery. (And that's the simplified version.)
This stuff is NOT what it was fifteen or twenty years ago, and most of the equipment makers are jealous of their trade secrets, as well as not wanting to confuse the customers about it. Marine and commercial chargers routinely have to be manually programmed to match battery type, specific voltage (12.6~12.8 down to the tenth) and amperage capacity. From all of the information Audi is processing (per the VCDS logs) it damn well looks like Audi is using a similar charge controller, with a computer and dedicated look-up tables that are used according to the battery coding.
Yes, the car should be smart enough to figure out "The battery is risen from the dead!" and adjust itself. But in practice, the new generation of controllers isn't quite THAT smart, even they need manual resets or periodic recalibration. Honest--I'm used to seeing this kind of programming as NORMAL in high end energy management systems. Even "low" end, under $100 (retail) BMSes. 10 years old.

Bob Petruska

There is no way that my state of the art CTEK charger knows what capacity that the battery being charged has. In fact, as your battery gets older, the capacity goes down, yet you can charge that battery to 100% SOC. The battery internal resistance also increases as it gets older.

Per my CTEC manual, all charging stages are triggered by "voltage" measurements and not current, notice that they never mention the word current.
Yes, current plays a major part, and eventually it will go down to almost zero during charging.

Start (Lamp 1)

Starting phase for charging. The starting phase continues until the battery’s terminal voltage
has risen over a preset level. At this point, charging goes into the bulk phase. If the
terminal voltage has not reached the preset level within 8 hours, charging is suspended.
The error mode is indicated. This indicates a battery which is faulty or has too large
capacity. If a large battery is charged that has been severely discharged, it may be necessary
to restart the charger after 8 hours. Start is indicated by lamp 1.

Bulk (Lamp 2)

Primary charging where approximately 80% of the charging happens. The charger
delivers maximum voltage until the terminal voltage has risen to the preset level. After a
number of hours, the charger goes on to the next phase, even if maximum voltage is not
reached. Bulk is indicated by lamp 2.

Absorption (Lamp 3)

Final charging, voltage is kept at the preset level. During this phase, the voltage is gradually
reduced. If the maximum length of time for Absorption is exceeded, the charger
automatically continues with Analysis. Absorption is indicated by lamp 3.

Analysis (Lamp 3)

Charging is suspended for a short period and the battery voltage measured. If it falls too
quickly, the battery is probably faulty. Charging is suspended and an error is indicated
(lamp 0).

Maintenance charging - float (Lamp 4)

During the first 10 days of maintenance charging the battery is maintained with constant
voltage, 13.6V. Float-maintenance is indicated by lamp 4.

Maintenance charging - pulse (Lamp 4)

The state of charge varies between 95% and 100%. The battery receives a pulse when
the voltage sinks, keeping the battery in good shape when it is not being used. The charger
can be connected for months at a time.
If the battery is charged and/or the battery’s terminal voltage drops, the charger starts a
charge pulse until the voltage has reached the preset level, 14.4V or 14.7V. The charge
pulse is then interrupted and the cycle is repeated as long as the charger is in pulse maintenance
phase. If the terminal voltage drops even lower, the charger automatically reverts
to the beginning of the charging curve. Pulse maintenance phase is indicated by lamp 4. If
possible, check the water level in the battery



The Audi BMS system is very complex and measures a lot of things and keeps a readings history..........



Express static current measurement
A so-called express static current measurement can be made in the Guided Fault Finding mode or the Guided
Functions mode under "61 - Battery control - Static current measurement using J644 - energy management
control unit" . The energy management system measures the actual static current in approx. 15 minutes. If the
static current is too high, a faultfinding program can be started directly from this program.

Data records
The following data records are available:
– Static voltage history
– Static current history
– Critical energy balance
– Power-down level history
-- Battery change history
– Energy balance of the previous 5 trips
– Energy balance of the previous 5 standstill
periods
– Date/clock time programming in the dash panel
insert

Structure of the data records

Static voltage history
In the static voltage history, it is possible to read out the following battery voltages:
● 12.5 V
● 12.2 V
● 11.5 V
The previous 4 entries, or "time stamps", are displayed.

Static voltage < 12.5 V : 46 hours
Static voltage < 12.2 V : 18 hours
Static voltage < 11.5 V : 9 hours
Static voltage history (raw data) =
Previous four values for static voltage < 12.5 V
The most recent value is listed first


Prolonged deviations below 12.2 V and 11.5 V are particularly critical.
If the battery voltage is below these threshold values, the battery will not be able to regenerate. This can result
in damage to the battery after a lengthy standstill period.
If lengthy deviations below 12.2 V and 11.5 V are ascertained, the battery must be tested.
The data are recorded under the following test conditions :
– Terminal 15 OFF for at least 2 hours
– Convenience CAN bus in Sleep mode
– Power consumption less than 100 mA


The evaluation of prolonged deviations above the static current is important. If 0 or 1 is displayed for the
duration the deviation above the set value, this means that the duration of the deviation above the set value
was less than or equal to one hour. Such entries can be disregarded because they are caused, among other
things, by the "TP memory function". If the value 0 is displayed for the static current, these are short current
peaks which can be disregarded.
High static currents can be caused by:
– the customer - if electrical consumers such as power supplies or vehicle fridges are connected to the
cigarette lighter supplied via terminal 30.
– the vehicle - in the event of a fault.
If the vehicle is required to have a high static current due to an awake bus system, no entry is made in the
history data under "Static current history" due to non-compliance with the test conditions (convenience CAN
bus must be in Sleep mode).
Test conditions are:
– Terminal 15 OFF for at least 2 hours
– Convenience CAN bus in Sleep mode
– Power consumption greater than 50 mA
The 50 mA current threshold consists of the following components:
– 25 mA max. permissible static current
– 25 mA for possible charging of the anti-theft alarm sounder
When a test is made using express static current measurement, 70 mA is output as the maximum permissible
static current. The difference can be attributed to an additional tolerance

Critical energy balance
This data record is only written if the vehicle is in an energy critical state (breakdown risk). The data record is
written if the energy management control unit recognises the condition "vehicle cannot be started". The most
recent data record is displayed at all times

Battery change history
The data from the previous 3 battery changes is stored in the battery change history.
The entry in the history data is made when the battery energy management system is encoded.
Therefore, it is very important that the energy management control unit J644 only be encoded when a new
battery has actually been fitted. Encoding deletes all history data. In this case, it will not be possible to
perform, among other things, a reliable battery test using the VAS 5051, because this test utilises the history
data. Likewise, it will be very difficult for Audi AG to comment upon queries submitted through DISS, because
the history data is no longer available or is falsified.

Battery
The battery is located below the left-hand seat in order to save space. Direct access to the battery is not
necessary for charging and checking the state of charge of the battery.
There are two slave start connectors in the engine compartment for charging and external power supply.
The battery state is checked using the energy management control unit J644.
If it is necessary to replace and check the battery acid level (e.g. during routine service work), the seat can be
easily folded up after undoing two screws.
The following batteries are used:
● 80 Ah / 380 A
● 95 Ah / 450 A
● 110 Ah / 520 A
The choice of battery depends on:
– Engine
– Equipment
– Country

MurrayA4

Man my head is starting to throb ! I remember when Ford were an early adopter of "smart" charging systems.Guess we can all guess as to how that turned out.
Redd excuse me if I missed it but what are you trying to accomplish here ? I recall that you were unhappy with the durability of the AGM in your vehicle.But somehow I suspect that you're up to more than trying to resolve that issue ?

Bob Petruska

Murray, all Redd is doing is replacing his OEM, 75 Ah, AGM battery with a 95Ah, AGM battery, looking for more reserve capacity, and there is some question as will an new 95 Ah BEM code actually change the BMS system to recognize it as a 95 Ah battery, or as a pre-programmed 75 Ah battery.

From what we know the new 95 Ah, BEM code most likely does not change any BMS parameters (capacity, charging profile, etc.), it just resets the BMS history and tells it a new battery has been installed.