Johngerard

Reading a few topics on the above, it would seem that the auxiliary pump is solely for the cabin heaterand in some cases will restart to circulate water through the block and head if the engine temperature exceeds 107c after shutdown, I read it that it should not affect the main cooling system which is carried out by the (belt driven?) switchable pump and thermostat. I have read in VW Vortex that several users have just by passed the auxiliary pump by connecting the pump inlet & outlet so it acts like the usual system. You could try this if handy yourself, of course you may have problems with that switchable pump variable shroud as well or elsewhere.

That cooling system is beyond me just now, I will try to get something from the VW self-study folders. There definitely shouldn't be any pressure with a cold engine, presume its not a vacuum being pulled?.

Have you a schematic of the cooling circuit with that auxy pump?, the heater exchanger is normally always in circuit and acts as the only path for the cooling circuit until the thermostat opens, it is then in parallel circuit with the radiator circuit, the cabin heat is controlled by air flow control through the heater matrix. If the cooling pump is acting up with that shroud (and it may well be) then you might expect more cabin heat before the thermostat opens at 86/90C. as all the water is circulating through the heater. You said in a earlier post that you get a lot of air each time you release the expansion tank cover, you should get little or no pressure normally, especially if you release it before the car idles for long, as the temperature is around 90C

You can try that, with great care. My tank (2019 Polo) isn't round and doesn't seem to have that bag, it is part no 200 121 407B.

Have a look at the side of the expansion tank and look for "Mit Silikat" written on it, if so, its possible that the bag of silicate has burst inside it and has clogged up the cooling/heating system. If you put "mit silikat" in the search box above you will see plenty of posts regarding it. Hopefully, this is not your problem but its a good starting point. Even with no problems, I occasionally slacken off, to release the pressure, the expansion tank cap (but do not remove it) after a run to release any air that may be present. I always do it immediately on getting a new car as air is very often entrained in the cooling system but I have never had to top up while new, the coolant level may rise (or fall) by 10mm or so in my experience.

If you sill have access to VCDS, go to advanced values (can't think of proper name) and get the following data, below. The usable battery charge, IDE01842 , and the battery voltage at rest, IDE01843, will tell a lot, take these values with engine OFF. You can do it with engine running afterwards for more info. You can also add Alternator output or generator output from the menu which you can monitor at the same time. IDE01834 Battery voltage 12.166 V IDE01836 Battery current -4.386 A IDE01837 Temperature of battery sensor 12 °C IDE01839 Battery charge level 79 % IDE01841 Battery internal resistance 7.8 mOhm IDE01842 Usable battery charge 28 Ah IDE01843 Battery voltage at rest 12.5 V IDE07681-MAS06086 Battery total charging throughput-Total re-charge 1354.8 Ah IDE07681-MAS06087 Battery total charging throughput-Entire energy throughput 1478.3 Ah

Your dealer's battery diagnostic's should be, at least as good as a Hex-V2 VCDS. Your battery seems to be recoded as the original serial number on all the batteries ends in 1, you just change any number on battery renewal. When I looked at battery adaptation for a AGM, it gave two choices, AGM Binary or Fleece. You can see from my log that the battery voltage at rest is 12.5V or ~ 80% SOC, 12.2V, IF taken at rest is probably ~ 55% SOC. but the battery voltage should really be taken "open circuited" for a accurate reading. I don't know how VCDS derives the at rest voltage. It shows a usable battery charge of 28AH in the 59AH, 3 year old battery, this is based on VAG's 50 X battery capacity, in this case, 2950AH and MAS06087 says total charging throughput was 1468AH so remaining, theoretically anyway, battery capacity is 59*1482/2950, 29.4AH so there or there abouts, apparently, when when the calculated MAS06086 reaches the actual measured charge throughput, MAS06087 then the BMS system starts shutting down non essential items such as stop/start. I charged my battery for 1 hour with a smart charger and it showed that the battery is/was close to its maximum SOC of ~ 80% which is par for the course I would think for regenerative alternator charging which will charge up to 15V on car overrun and 12.8/13.5V normally. I would advise you to borrow VCDS from someone to get a reasonably accurate feel for your battery condition but if it is falling as low as 11.0V (when freezing) then I would be concerned. 14:58:57 24/1/2022 Polo AW1 registered 03/01/2019. Build date August 2018 (Engine OFF) IDE01834 Battery voltage 12.166 V IDE01836 Battery current -4.386 A (mainly from the DRLs) IDE01837 Temperature of battery sensor 12 °C IDE01839 Battery charge level 79 % IDE01841 Battery internal resistance 7.8 mOhm IDE01842 Usable battery charge 28 Ah IDE01843 Battery voltage at rest 12.5 V IDE07681-MAS06086 Battery total charging throughput-Total re-charge 1354.8 Ah IDE07681-MAS06087 Battery total charging throughput-Entire energy throughput 1478.3 Ah 19:25:42 24/1/2022 after 1 hour charge. IDE01836 Battery current -5.689 A IDE01837 Temperature of battery sensor 16 °C IDE01838 Battery temperature 16 °C IDE01839 Battery charge level 82 % IDE01841 Battery internal resistance 7.6 mOhm IDE01842 Usable battery charge 30 Ah IDE01843 Battery voltage at rest 12.5 V 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 Open circuit battery voltage (lead acid?) Volts Capacity % volts/cell 11.51 10 1.918 11.66 20 1.943 11.81 30 1.968 11.96 40 1.993 12.10 50 2.017 12.24 60 2.040 12.37 70 2.062 12.50 80 2.083 12.62 90 2.103 12.73 100 2.122

Can't comment on Eco mode, but normally there is no fuel injected on overrun, in gear (clutch engaged), and RPM > ~ 1200 RPM and engine temperature above something like 30C. All my (petrol) cars have operated like this since 2000, my first MPI engine.

17 year old Polo N doesn't give up its secrets to VCDS like the mk10 but got readings with ammeter connected between disconnected earth strap and negative battery terminal. The original resistor pack is in this car. I installed two pollen filters in the 17 years. Fan powers very similar in both models. 23/03/2022 Engine OFF Battery Engine Off Amps speed 0 -1.85 speed 1 -5.5 speed2 -8.1 speed 3 -12 speed 4 -18 Fan Amps (calc) speed 0 0 speed 1 3.65 speed2 6.25 speed 3 10.15 speed 4 16.15

Just wonder how accurate is the battery charge/discharge (amps) measurement device on the negative terminal is, at very low inputs, I presume it has to be calibrated to measure up to 400/500A to cater for the cranking current, but must still be accurate for very small battery charging rates for the BMS. Assume a range of 0 to 500A, 5A = 1%of range, 500ma = 0.1% & 50ma = 0.01% so no wonder it shows 0ma. This car is on its second replacement cabin fan resistor pack, it third in all and I monitored the current draw at the different fan speeds, both with engine off and engine running. The fan loads on speeds 1&2 don't make any sense with engine running, so wonder why this is, I am subtracting the (charging current+the current usage with engine off) from the Alternator output so either my calculations are wrong or something(s) arn't being measured accurately? The battery volts with engine off are 12.35 to 12.7V. 20/03/2022 Engine OFF 20/03/2022 Engine ON Battery Battery Alternator Battery Engine Off Amps Engine On Amps Amps Volts speed 0 -4 speed 0 4 5.5 13.50 speed 1 -8.6 speed 1 5.3 7.4 13.46 speed2 -10.9 speed2 4.9 9.2 13.45 speed 3 -15.5 speed 3 4.5 17.5 13.44 speed 4 -21.7 speed 4 4 26.5 13.40 Fan Amps (calc) Fan Amps (calc) speed 0 0 speed 0 -2.5 speed 1 4.6 speed 1 -1.9 speed2 6.9 speed2 0.3 speed 3 11.5 speed 3 9.0 speed 4 17.7 speed 4 18.5

Apoligies, correct, the hex+usb did work on this 2010 car, (it was on a neighbours 2020 Golf that it didn't) , as I didn't purchase the hex-v2 until 2020,

Yes, you definitely need the Hex-V2 which gives full support and is backwards compatible to all vehicles, the Hex-USB+CAN didn't even work on daughters 2010 Golf.

Just discovered a few days ago that VCDS (on this car anyway) maintains communication after switching off the ignition and removing the key and locking the car so I observed the battery voltage/current, on locking the doors the indicated voltage/current is 12.65V/2.6A, the amperage falls to 1.16A after around 30 secs or so and to a indicated 0.0 A after 90 secs or so with a indicated voltage of 12.85V so definitely while 0.0 A parasitic loss is highly improbable, it may be practically 0A for periods and then wakes up and do a few checks? before going back to sleep, same indications if I unlock the door and then just open/shut it to prevent it auto locking after 30 secs, it indicates 0A after 90 secs with doors remaining unlocked. I will try that on the 17 year old Polo 9N which always seemed to have a parasitic loss of 95ma when measured with a M.meter connected between the disconnected earth strap and the battery negative terminal

With engine running but all auxiliaries off check voltage, then with heated rear screen, dipped beams and fresh air fan on speed 2 or equivalent check voltage again.

11.3 volts is < 10% capacity, if it rises to 12.3/12.5V after engine switch off after a 15/30 min run then more than likely that the charging system is OK and the battery either on the way out or you have a very large parasitic loss. If the battery is OK then it would need to be charged with a external charger as you will be wasting a lot of fuel trying to trickle charge it from the alternator controlled by the energy saving BMS system. With what & where are are you measuring the battery voltage.

I've seen transport mode in the VCDS so it makes sense, I think you can't then reactivate it after the car has travelled a a 100 miles or so as the it will have been delivered by then.

Every car that I've/family owned (all VWs) were purchased new and all I would think were in one form of storage or other for up to 6 months, all (apart from present Polo) were/are just lead acid types and all apart from one (my first car, a 6V 1963 Beetle, whose battery failed after 5 years) lasted > 10 years, not one failed and I only replaced them as the car(s) were handed on. The present Polo has a Botswana build label which shows 19/4/2018, I registered this car on 03/01/2019 so lying around somewhere for 8 months or so. So batteries must have either been topped up regularly as the parasitic loss would flatten then in ~ 5 weeks or so, or they were stored with battery disconnected of they were simply left flat for months on end?.

That charging pattern looks very similar to mine, however, a bit concerning that the voltage falls from 12.1 (50% SOC) to 11.3 which is less than 10% capacity.

I take your point obviously but you can monitor it though through the window of the drivers door?, I can't do that as having a voltmeter/m.meter permanently plugged into the cabin power socket is no good for monitoring the above as the socket is dead until the ignition is on but I am reasonably happy that VCDS does give a true reflection of the battery at rest battery voltage which still is not a true indication of the SOC as it should be done with a open circuited battery, but is IMO good enough for most purposes. I only want this battery to last 10+ years like all my other ones!!.

It does "recover" instantly, ie if I relock the doors the voltage rises immediately from 12.33 to 12.46V & if I unlock he doors, the voltage goes from 12.46 to 12.33, these numbers may change if I wait 15/20 minutes each time??. Even from new I have never seen the standing charge (VCDS indicated) higher than 12.5V) Can you see what the instantaneous changes are, doing the same tests and if these value(s) change again after this time period?.

Couldn't do your test as I don't have a permanently installed voltmeter but (with bonnet opened) terminal voltage just now 12.46V, car locked, and 12.33V car unlocked (no DRLs in both cases), if I then relock the doors battery voltage returns to 12.46V, this gives a load of 16.7A, (0.13/7.8*1000), really can't account for this as obviously can't be continuous.

My battery's Vd of 0.334V, (12.50-12.166), gives a likewise unlikely load of 43A?. from the VCDS but only a Vd of 0.08V, (12.18-12.1) from the M.meter readings giving a more realistic loading of 10.26A. I will carry out your tests above later on today.

The SOC voltage should ideally be checked with the battery terminal(s) disconnected, VCDS apparently measures the battery at rest voltage but the only way it can is if the at rest voltage is stored in the BMS system because the ignition must be switched on for VCDs logging which means the load is at least 4.4A from the DRLs which with a battery internal resistance of 7.8 mohms will account for ~ 0.04Vd apart from any other parasitic loss or loads. Your readings above indicate a 0.4Vd, indicative of a unlikely load of ~ 50A at a battery resistance of 7.8mohms.

It might but the killer IMO is the battery internal resistance, if you use the 3 year old battery (59 AH) resistance above of 7.8 mohm as typical then assuming a petrol engine with a 1kw starter motor will require 200amps at a nominal 10V & 50% starter efficiency, voltage drop while cranking, 200*7.8/1000, almost 1.6V, so your cranking voltage was ~ 9.8V?. Batteries even when almost completely knackered can start a car once (only) each time after a recharge or stopping after a run. My neighbours 2011 diesel Opel Omega failed to start a few weeks ago (original 95 AH? battery), the terminal volts were 11.8 so I connected in my 3.8A smart charger, after 32 minutes the battery/charger were up to 14.3V and the charger then went into trickle mode, 15 minutes after disconnecting the charger the terminal volts were 12.5 and the car started immediately and was constantly charging at 14.3V so alternator OK, next morning same story, no start, so new battery (after 10 years). Its amazing that my charger had only put 2AH into this battery in 32 minutes and it was then capable of starting the car even if only once, I can only explain it by the fact that while a cranking current of say 400A (this was a 2 litre diesel) is required the energy (AH) required is quite small, a 3 sec crank at 400A only requires 0.33 AH.