Johngerard

All the VWs I've had since 2000 don't require the HRS on to enable the mirror heating, it would be much better IMO if they just came on/off with the HRS or switch off automaticall after 20 minutes or so like the HRS, I also saw something in VCDS about the temperature setting of the HRC, maybe 34C? which I think is settable so wonder can this also switch off the HRS before the time out period.

Probably, the DVM is excellent for showing the charging pattern but does read 0.2V ish lower than what VCDS or the actual measured terminal volts show, I've certainly seen DVM readings of 14.8V so would think that occasionally the charging votage goes as high as 15V. I will log a few VCDS readings on the run soon.

What is fake recuperation and how is it switched off ?

Even with a "fully" (85%) charged battery, these BMS systems will always charge at 14.6/14.8V immediately after starting but normally only for 20/30 seconds or less and will then charge at 13.3/13.6V, but on overrun will always charge at this higer voltage. I have a DVM (digital volt meter) permanently plugged into the auxiliary power socket so quite easy to see the charging behaviour, they only cost less than a fiver. I would monitor the battery terminal voltage with a multimeter while someone starts the engine, you should then see the voltage rising to ~ 14.8V for a brief time. Even so, that Low 12V battery alarm should not be up at anything above say 12.4V. Borrow your friend's VCDS and take a set of readings as below, will give some idea of what's what, these are mine for a 6.8 year old Polo with its original 59AH EFB battery, these were taken with ignition switch only on hence the negative battery current, due to the daylight running lights etc., but readings can also be taken with engine running. IDE01834 Battery voltage 12.313 V IDE01836 Battery current -4.420 A ID01837 Temperature of battery sensor 21 °C IDE01839 Battery charge level 82 % IDE01841 Battery internal resistance 7.4 mOhm IDE01842 Usable battery charge 33 Ah IDE01843 Battery voltage at rest 12.5 V IDE01948 Battery internal resistance not normed 5.8 mOhm

Don't most VAG engines now have two stats?, mine (a 2019 petrol Polo) has, with opening temperatures something like in the attached, if so, should both be tested in the event of a overheating problem?. See (VW SSP 820333 pdf) Two Stat Photos.docx

My original 6.8 year old battery never charges at less than 13.5V/1.0 to 2.0A, even with a SOC of 83% and 14.7/14.9V on the overrun, its possible that your OBDelevan is reading ~ 0.5V low, in which case the battery charging looks about correct but again I can only suggest getting the battery coded properly to remove all doubt.

Does the DVM show charging characteristics like mine, (DVM), normally only 14.8V on the overrun? and have you taken any VCDS readings recently?

Battery, believe it or not, back up to 82% SOC after another 2 hr round trip, on the 1 hr outward trip. its normal 14.8V on overrun only, otherwise its normal 13.5V but on the return trip charged at a constant 14.4V continuously for 35 minutes and then back to its old ways. I won't post again until either the battery or I die!! 18:57:34 20092025 IDE01834 Battery voltage 12.313 V IDE01836 Battery current -4.420 A ID01837 Temperature of battery sensor 21 °C IDE01839 Battery charge level 82 % IDE01841 Battery internal resistance 7.4 mOhm IDE01842 Usable battery charge 33 Ah IDE01843 Battery voltage at rest 12.5 V IDE01948 Battery internal resistance not normed 5.8 mOhm IDE07681-MAS06086 Battery total charging throughput-Total re-charge 3441.7 Ah IDE07681-MAS06087 Battery total charging throughput-Entire energy throughput 3630.8 Ah

Yes, 14.6/14.9V is quite normal after every start, it might tell the OP something about the state of his Alternator even if it does drop back to 12.5V which IMO will not charge any battery, might give a trickle charge of 0.5/1.0 amp, as you are probably well aware all the older type VAGs charged at a constant 14.2/14.4V to give, in my case, a minimum of 10years battery life and even then I used only change them as a precautionery measure as the car was handed down the line. It mightn't be bad advise if the OP got the battery coded and also invest a fiver or so in a DVM, (digital volt meter) and he can keep an eye on the charging patterns. "When your Car have every time min 13,X Volt, your Batterie ist EOL" what is EOL? and ""Fake" rekuperation?", as stated, I've never seen the DVM displayed voltage fall below 13.3/13.5V under any circumstances.

Are you saying it never went to 14.8V on overrun? My 6.8 year old battery has a 70% SOC but allways goes to 14.8ish on overrun and never below 13.5 when driving normally, I can't see any battery lasting very long if charging for any extended time at 12.5V. If you monitor the battery terminals with your M.meter and get someone to start the car, then after start up,the voltage will/should rise to almost 15V but only for ~ 15/20 secs.

Even without coding I would be very surprised if the charging voltage ever went below 13.5V or so, the BMS will allways charge at 14.8V/15.0V on the overrun but nearly allways 13.5ish while driving normally, if you turn on all the auxiliaries does the M.meter still show 12.5V while idling or increasing the revs a little, if it does then possibly the lack of coding, if not, possibly a Alternator problem.

I've replaced several throttle bodies for people with used ones and they have never required re adapting, the engine takes a few minutes to return to normal idling speeds.

Re the throttle body, if its like my Polos, then if you press the accelerator with just the ignition on, the throttle valve should open fully. You should also be able to move off by just releasing the clutch pedal without leg on the accelerator and also go up a fairly steep incline in first gear without any accelerator.

Generally speaking, I find that if the (a) car is driven even for 2 or 3 miles daily then one should get a reasonable battery life, my Jan 2019 Polo has no problem with the stop/start on the rare occasions that I enable it and will do so after driving the mandatory 500 meters even if parked up in the airport for 8/10 days. It wouldn't do any harm to invest less than a fiver on a DVM (digital volt meter) and leave it permanently plugged in to the cabin power socket, you should find that the battery charges at 14.8/15.0V allways on the overrun and ~ 13.6V while driving or idling. The batteryhas never indicated more than 85% SOC, even when new, one might think that at its present alleged 71% SOC that it would charge at well over 14.0V to get the SOC back up to 85% but it doesn't, on a 2 hour trip a few weeks ago it just did its usual 14.8V on overrun and 13.5V ish, while driving normally but I will be happy enough if I can knock around 8 years out of this battery, car has only 23,000 miles up but as stated above, driven daily. If I check the battery current (VCDS) sitting in the car with the doors locked and ignition key out, it reads ~ 2.5A for a few minutes and then falls to zero, presumably means little or no parasitic loss, all my previous cars had a parasitic loss of ~ 40mA when measured with a multimeter in series with the battery, but one, a 2005 Polo, still in the family had/has a parasitic loss of 85mA from new and even with a 10 year old battery would start up after being parked up for a week or more, after a draw down of presumably ~ 16AH from a 44AH rated battery, of course these cars charged properly at a constant 14.4V. (VCDS readings taken with engine idling) Original, 59AH, EFB Battery, 6.7 years old. IDE01834 Battery voltage 13.499 V IDE01836 Battery current 2.828 A IDE01837 Temperature of battery sensor 34 °C IDE01839 Battery charge level 71 % IDE01841 Battery internal resistance 7.8 mOhm IDE01842 Usable battery charge 26 Ah IDE01843 Battery voltage at rest 12.4 V

Did this 2 hour trip and its quite apparent that the BMS system will now only charge to ~ 70% SOC, it does charge at ~ 14.9V/20A, but only for 15 secs or so after a (stop/start) restart and then falls back to 13.5V but does go to 14.9V on overrun. 15:22:30 12092025 immediately after 2 hour country trip. (VCDS readings taken with engine idling) IDE01834 Battery voltage 13.499 V IDE01836 Battery current 2.828 A IDE01837 Temperature of battery sensor 34 °C IDE01839 Battery charge level 71 % IDE01841 Battery internal resistance 7.8 mOhm IDE01842 Usable battery charge 26 Ah IDE01843 Battery voltage at rest 12.4 V IDE01948 Battery internal resistance not normed 7.8 mOhm IDE07681-MAS06086 Battery total charging throughput-Total re-charge 3422.3 Ah IDE07681-MAS06087 Battery total charging throughput-Entire energy throughput 3611.6 Ah

All modern VAG group cars are only charged to a max of 85% by the Alternator so don't really know what that 90% means in VW terms, my VCDS numbers below show the state of mine after 2years 8 months, the (VCDS) charge level is based on "the battery voltage at rest" value which I didn't take in 2021 but the usable battery charge, AH, might be the more meaningful one, mine apparently has gone from 38AH to 33AH in 4 years so hopefully a few more years in this battery, it would be interesting if you could get someone with VCDS to run a scan on yours 14/09/2021 (Battery 59AH EFB, original, from January 2019) IDE01834 Battery voltage 13.487 V IDE01836 Battery current 2.639 A IDE01837 Temperature of battery sensor 32 °C IDE01838 Battery temperature 27 °C IDE01839 Battery charge level 85 % IDE01841 Battery internal resistance 6.6 mOhm IDE01842 Usable battery charge 38 Ah 12/07/2025 IDE01836 Battery current -4.924 A (engine off, elec load mainly from the DRLs) IDE01837 Temperature of battery sensor 35 °C IDE01838 Battery temperature 37 °C IDE01839 Battery charge level 83 % IDE01841 Battery internal resistance 8.0 mOhm IDE01842 Usable battery charge 33 Ah (59AH Battery, original, 6.5 years old) IDE01843 Battery voltage at rest 12.6 V

10 MPH seems extremely high, mine is more like 3 MPH and because it is a manual then it will only do this if the car is out of gear and in neutral because even in first gear the speed never drops below ~ 6MPH and even if it did I would think the ECU would know this and inhibit the stop anyway, surprising as well that it doesn't know if its "in gear" if a automatic but maybe these DSG gearboxes are different?, anyhow it still shouldn't shut down the engine until the car is practically at a standstill, if mine just starts moving (say on a incline) the engine will restart before the speed even registers.

I must check that out in my Polo where I only use Stop/Start as I see fit, but no problem with that. I often move along in traffic, (stop/start enabled), in first gear with leg off the accelerator, the car will actually climb a moderate incline like this and I often take off without pressing the accelerator in heavy traffic, or even leaving my own drive, the only time I've noticed the engine cutting out before coming to a full stop is if I take it out of gear, then release the clutch, and let it coast up to the car in front or to the traffic lights etc.

Have you checked for cracked hoses around the inlet manifold, PCV valve etc, it might be worth replacing the PCV valve, not very expensive, I think, did anyone check the manifold depression while idling, could be fault with brake servo.

The only time I use my multimeter 0-10A scale is to measure the charging current when I'm using the smart charger which I know can't exceed 5A, just change over one lead on the meter, any other measurements are taken with the VCDS, any value you see with a IDEO prefix is from the VCDS. Yes, a pity I didn't take a set of readings when new but there are 4 years between the two sets above which give 38AH usable battery charge after 2.7 years vs 33AH after 6.5 years. I changed the battery in my daughters Sharan last December and would be confident that I coded it properly but the readings taken immediately afterwards are a bit confusing, the battery is a 70AH, 096 Ecoforce AFB Fiam and the "70 Battery Size" seems to bear this out but it then says "100 Ah Available Battery Charge". My battery internal resistance showed 6.6mOhms after 2.7 years and 8.0mOhms after 6.5 years, the cranking voltage drop at the battery terminals that I measured last week with my trusty M.meter was 12.17-10.7, 1.47V which suggests a cranking load of 184A with a battery resistance of 8mOhms, anyway that's the simple test I use if anyone's battery is suspect, just measure the voltage while cranking, if below say 9.5ish volts then something not right, a M.meter will show up most of these problems and did 50 years or more before VCDS was a thought. Sharan New Battery December 2024 70 Battery Size 14.848 V Battery Voltage 8.1 A Battery Current 100.0 % Battery Aging (Power) 4.6 mOhm Internal Resistance Battery 2.2 mOhm Internal Resistance Battery (normalized) 100 Ah Available Battery Charge 11.40 V Battery Quiescent Current 1 Total Engery Throughput II 0 Total Engery Throughput I

Yes, a VCDS, the 75% to 76% isn't borne out by the 28AH each time. During the previous charging sessions which I now know were (probably) 0.8A for 12 hrs and then 0.2A for another 12 hrs, the SOC went from 65% to 74% in the first 12hrs and no change in the second 12hrs, based on this, I would think, as you suggested, that any of the other chargers would perform any differently, I will be doing another 2 hour trip in the not too distant future so will see if the Alternator will increase the SOC even though averaging just 1.6A while driving at least short journeys, the last time it was showing 83% (after a 2 hr trip), the usable battery charge was, I think, 32AH, not bad, when compared to the first readings I took when the car/battery were 2yrs 8mnts old. 14/09/2021 IDE01834 Battery voltage 13.487 V IDE01836 Battery current 2.639 A IDE01837 Temperature of battery sensor 32 °C IDE01838 Battery temperature 27 °C IDE01839 Battery charge level 85 % IDE01841 Battery internal resistance 6.6 mOhm IDE01842 Usable battery charge 38 Ah 12/07/2025 IDE01836 Battery current -4.924 A IDE01837 Temperature of battery sensor 35 °C IDE01838 Battery temperature 37 °C IDE01839 Battery charge level 83 % IDE01841 Battery internal resistance 8.0 mOhm IDE01842 Usable battery charge 33 Ah (59AH Battery, original, 6.5 years old) IDE01843 Battery voltage at rest 12.6 V IDE01948 Battery internal resistance not normed 5.6 mOhm

During a 20 minute daylight run (daylight) the battery charged at a average of 1.6A at 13.66V, including a average of 16.9A at 14.93V on the Overruns, the SOC was 75% with a usable battery charge of 28AH, (59AH EFB battery). I then connected the charger with my multimeter in series measuring the charging amps, it went to 14.4V for ~ 15secs charging at 3.8A then fell to 13.4V charging at a constant 0.8A for the next 2 hrs and then fell to 13.1V at 0.2A for a remaining monitored time of 1 hour, then removed it, SOC 76% usable battery charge 28AH. While the Alternator just eventually might get the SOC back up to 83% if the car was driven long enough, it doesn't seem very clever since the battery can clearly absorb up to 30A and even with all the auxiliaries switched on, was being charged at 12/15A on the overruns. The charger it seems would never get the SOC back up, wonder would the fancier/more expensive ones fare any better.

NO fear of me getting hung up on these numbers but I do find them interesting. I would fairly confidently say though that had this battery been charged at at a constant 14.2/14.4V like all my previous cars to this one that I would see at least 10 years battery life because this car is operated very similar to the last Polo still in the family (20 years old now) and I only replaced that battery as I was passing it down the line. Taking the smart BMS charging system, even though this battery was allegedly at 24A/65% SOC it was still only being (Alternator) charged at 13.5V and ~ 1.0A but, a few weeks/months ago when the SOC was 74% or so, it charged continuously at 14.4/14.8V for practically the whole of a two hour trip and only returned to 13.5V just before the trip end but it did again, (allegedy) reurn the battery to ~ 83% SOC, strange? Re my smart charger, I would think that it did charge at 0.8/1.0A for the first 12 hours, which increased the SOC from 65% to 74%, and only maybe 0.2A for the other 12 hours, hence the SOC stayed exactly the same, I wonder would one of these other fancy chargers do any better? or can be set to "load" charging, ie say, you set it to 3 or 4A and the charger will increase the voltage to (try) and achieve this, otherwise, IMO, one has no control over the SOC except maybe to use the charger as soon as you get a new battery and assume/hope its at 100% SOC., what a PITA. I will connect my M.meter (10A) in series with the smart charger next time and see what its doing.

Can't see without taking the top off, VCDS states IDE03256-MAS06105 Battery adaptation-Rated battery capacity 59 Ah IDE03256-MAS06106 Battery adaptation-Battery technology EFB IDE03256-MAS06107 Battery adaptation-Battery manufacturer JCB IDE03256-MAS06108 Battery adaptation-Battery Serial Number 1111111111

For the first time in over 62 years of driving I put my battery on charge for 2 x 12 periods, the smart chargedr is a 5A, Ultimate Speed ULGD 5.0 C1, it charged at a continuos ~ 13.1V after briefly hitting 14.4V for a few minutes and should have been charging at ~ 0.7/0.8A which is "verified" by the charge level increasing from 66%(24AH) to 74%(32AH) in the first 12 hrs charge period, this charge level stayed the same for the next 12 hr charge period which suggests to me that this my new now max charging level, the Alternator is fine because at idling, with the fan speed on its max of 4, the HRS ON and the headlights on, it still slightly charges at ~ 0.2A, the battery at idling at 13.3V and charges at slightly over 1.0A at idling or driving normally with no auxiliaries on. It doesn't run continuously at 14.8V even with the now 74% charge level which suggests that the battery is, as expected, deterioriting, after 6.5 years, so we'll see what happens. From what I am seeing, the Stop/Start will operate (on this cart ) until the battery is on its last legs, at 65% charge level it stopped and started 6 times in less than a mile and after a hour or so the stop/start gain worked perfectly after its customery 500/600 meters. 11:12:41 30/8 engine idling IDE01834 Battery voltage 13.325 V IDE01836 Battery current 0.153 A Fan Speed 4, HRS ON, Headlights ON. IDE01839 Battery charge level 74 % IDE01843 Battery voltage at rest 12.4 V 11:11:40 30/8 engine idling IDE01834 Battery voltage 13.500 V IDE01836 Batterycurren1.223V IDE01839 Battery charge level 74 % IDE01843 Battery voltage at rest 12.4 V 11:13:32 30/8 IDE01834 Battery voltage 13.509 V IDE01836 Battery current 1.086 A IDE01839 Battery charge level 74 % IDE01843 Battery voltage at rest 12.4 V 23:34:13 28/8 After another 12 hr Smart Charging, 24 hr in all IDE01834 Battery voltage 12.311 V IDE01836 Battery current -4.305 A IDE01839 Battery charge level 74 % IDE01842 Usable battery charge 32 Ah IDE01843 Battery voltage at rest 12.4 V 23:34:13 After 12 hr Smart Charging IDE01834 Battery voltage 12.311 V IDE01836 Battery current -4.305 A IDE01839 Battery charge level 74 % IDE01842 Usable battery charge 32 Ah IDE01843 Battery voltage at rest 12.4 V 07:48:16 Before(12 hhr Smart Charging) IDE01836 Battery current -4.414 A IDE01839 Battery charge level 65 % IDE01842 Usable battery charge 24 Ah IDE01843 Battery voltage at rest 12.3 V