Originally Posted by
masster
This topic made me register for this forum.
I own a Tiguan Mk1, 2015, 1.4 TSI 122hp R-Line, with a Start/Stop function and a button on the centre console to disable it. Most of the time I disable that stupid feature. Several times I had the unpleasant surprise of not being able to start the engine.
hmm.......... your Mk1 Tiggy was built with a PQ46 platform whereas the original vehicle which was the subject matter of this thread (mk2 Tiggy) was built with a MQB platform - very, very different cars!!!
An important difference between the mk1 and mk2 vehicles was the role of the EMS - in the mk2, the EMS was managed by J533 which is called "Gateway" module by various diagnostic devices and in the mk1, the EMS was controlled by J519 (the BCM).
Simply because the 2 x vehicles use the same name (EMS), doesn't mean that the EMS has exactly the same function. Almost certainly, the EMS in the later MQB platform car is the next version EMS (and therefore almost certainly, it was more sophisticated)!
Originally Posted by
masster
Here is my opinion. Although in theory, BCM should do a great job, in reality, it doesn't allow the battery to charge more than 50%. Most of the time the battery has 12.2 V in the morning. I tested if there is a parasitic draw and the car sleeps rather quickly to about 5mA consumption overnight.
Why do you believe that "it [BCM] doesn't allow the battery to charge more than 50%" ? The position suggests that the Regeneration function of Start Stop (i.e. energy recovery during braking) can recoup up to 50% of the battery capacity. This is NOT technically feasible, regenerative braking simply isn't that efficient- no offense intended!!
Originally Posted by
masster
Of course, we don't have the luxury of having clearly displayed on our dashboard the State of Charge (SOC) of the battery, which should be mandatory. Why isn't BCM doing that beats me. It would be more useful than a simple battery red alert indicator.
As I said in my first response to OP "With early MQB cars, VW allowed drivers to view the battery State-of-charge (SOC) measurement which invariably showed 80% . This facility was withdrawn in later models because (I suspect) drivers kept complaining to VW" that full battery capacity was not being achieved.
Note the 80% number - this is an actual SOC measurement on early MQB platform cars. The number is NOT "50%"
Originally Posted by
masster
Nevertheless, I will disconnect J367 too because I can't risk myself to get stuck in traffic or at home just because the BCM does a poor job. By the way, my Varta 65 Ah battery is special for the start/stop feature and I coded it correctly using VCDS.
OK - this is entirely your decision (and wholly your right) - My view is that the short term benefit that you believe results from disconnecting J367 comes with a long-term cost of compromising the longevity of your expensive battery!! But again, your decision!!
Finally, below is an extract from a post that I wrote on the OBD11 forum regarding J367 - which I call the "Battery Monitor Module" (BMM). Hopefully it will help in your understanding of this matter - ignore reference to mk8, the dialogue is equally applicable to your mk1 Tiggy
This is a diagram of what's inside the BMM and what information the data-stream provides to the car's EMS - I thieved this picture from a
MQB platform car -but I expect that it is equally applicable for a MQB-evo vehicle like a mk8 (note the BMM is called J367 in the VW wiring diagrams):
As I have said, I suspect that the LIN facility in the diagram above is replaced by a pair of CAN wires on a mk8 and I expect that on this 2nd generation version of the BMM, the functions that use the battery information stream is even longer!! However, my assumptions about a mk8 notwithstanding - what's clearly evident from the function list above is that the BMM data-stream is pivotal to a wide range of EMS decisions - extending well beyond the SS facility
I've argued in other forums that deleting the BMM data-stream from the EMS must affect the performance and longevity of the battery on cars that have SS. These EFB/AGM batteries use more sophisticated manufacturing methods than normal flooded-cell techniques and they require more disciplined charging regimes to maximize performance and battery life.
Notice the Shunt resistor in my diagram above - this component of the BMM measures EVERY milli-ampere of electrical current that is either drawn-from, or injected-into the battery over the life of the battery. So, together with the Battery information that the hex19 module stores as adaptation channels when the battery is installed into the car, the EMS maintains a complete history of battery capacity and it uses this historic data to adjust the optimal charging profile for maximal battery longevity! When the hex19 module is told that the BMM is not installed (via this tweak) - this entire data-stream is lost to the EMS!!
Last edited by DV52; 14-10-2024 at 09:50 AM.
Please don't PM to ask questions about coding, or vehicle repairs. The better place to deal with these matters is on-line, in the forum proper. That way you get the benefit of the expertise of the wider forum! Thank you.
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