Johngerard

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

Normally, if you just turn the ignition but do not start the car then the fuel pump relay is energised (to start the pump) but only stays energised for maybe 5 seconds or so, its definitely more than a second or two to allow the car to start which then sends a signal probably from the RPM sensor to the ECU to keep the relay energised, in the even of a collision or if the engine stalls then the relay is also denergised for safety reasons. I would just switch on or get someone to switch the ignition on and monitor the time taken before the relay deenergises again.

As above with the spark .... Could be the petrol pump, easy enough to check, if the wiring plug is removed and someone has a multimeter and can use it, its accessed under the back seat, on my Polos anyway.

When the engine is heating up the VCDS (true coolant temp) might look like this, the ECU modifies the temperature Gauge to read exactly exactly 90C until the temperature rises to a (true) ~ 107C, is yours reflecting this, the fan if controlled by a coolant temperature sensor must read the true temperature?. The basic fan speed control is just a thermoswitch with two sets of contacts and two speeds, (one controlled by a resistor in the fan motor) screwed into the rad header. VW Polo 02092024 Coolant Temp VCDS (true temperature)/Car (coolant gauge) 52 /52 53/55 56/58 58/62 60/65 63/69 64/72 66/74 68/78 69/82 71/84 73/86 74/88 75/89 75/89

The heated rear screen doesn't activate until the engine is running even if switched on I think, and has been that way for years.

It most certainly wouldn't be IMO, I monitored it with the VCDS one time and coolant temp was something like 25C with a ambient of 5C after 500/600 meters, apart from being frozen almost to death if you left the stop/start enabled and just doing very short trips then you would probably need to get the engine replaced every 4 years or so as well, of course you could fit it in when they are renewing that pesky battery at the same time!. Also, I noticed one time that after driving around 50 miles (stop/start working because the ambient was ~ 0C) when the engine etc would be well warmed up that the ambient temperature dropped below -2C and the stop/start was again disabled, logic at its very best.

Batteries are a bit of a mystery to me, you frequently read posts re over and under charging or whatever, I knew several people who's batteries lasted for 8+ years, even though constant charging at 14.2/14.4V while driving for well over 4 hrs every day, my own cars, with bog standard lead acid (original) batteries all lasted for 10+ years, also charging at this constant 14.2/14.4V, some cars doing aroud 15K miles/year, others ~ 3k miles/year, but very rarely if ever requiring topping up with a drop of distilled water. Fast forward to modern times where batteries are now only charged to ~ 85% SOC so I wonder does this give reduced or increased battery life vs 100% SOC assuming same operating conditions. I would also be a bit doubtful about the longevity of battery life where the car is only used say once every few weeks but kept fully charged with a smart battery charger, but perhaps they do/will last for years. My only experience of "shelf like" charging is the 12V 7.2AH battery in my house alarm cabinet which only ever operates in anger during the very very seldom times when we get a elec mains blackout of generally a few hous only, I replaced it after 7 years purely as a routine. This battery is charged continuously while installed in the alarm cabinet.

This VCDS scan of a Polo coolant Temp will give some idea of your actual temperature. You can see that with a true/actual temperature of ~ 75C then the coolant gauge will indicate 90C, it will remain showing this 90C until or if the actual coolant temp reaches ~ 107C and then start displaying the true temperature again. (I've obviously not verified this). As noted in another post, it does look as if the new stat is either stuck open/partially open, very unlikely IMO, or is the incorrect one, allowing coolant to by pass into the rad. My Polo has got two coolant stats set to different opening temps but I don't think they are interchangeable VW Polo 191C561 02092024 Coolant Temp VCDS(true temperature)/Car coolant Gauge 52 /52 53/55 56/58 58/62 60/65 63/69 64/72 66/74 68/78 69/82 71/84 73/86 74/88 75/89 75/89

I'm not sure but I think I did see the voltage drop from its usual 14.8V on overrun to 13.6 ish on a 4 hour trip one time, so probably will do likewise if "100%" charged?

The parasitic loss in this car must be very very low because we often go abroad for 10 days or so, on return, as soon as the car has travelled its mandatory 500 meters to arm the stop/start, the engine will immediately shut down if I re enable it, I can't remember but I think the low voltage inhibit is set at something like 12/12.5V, however even though its never lower than 13.2/13.5V with all auxiliaries on the stop/start is disabled at fairly high electrical loads. It clearly states in the manual that one of the conditions for enabling the stop/start is that "a minimum engine temperature has been reached" This certainly does't apply to this car, as long as the ambient temperature is > -2C then the stop/start is enabled once you drive 500 meters even after been parked up all night, however I don't get neurotic about it as I do find it useful at times.

Even if your battery is fully charged, assuming its a VAG car, then it will still only be at 85% SOC and assuming ~ 75AH battery, it will still take around 24 hrs to bring it up to 100% assuming your smart charger is probably only charging at about 0.8A after its initial 3/5A or whatever, i wonder would my 6.5 year old battery now achieve this, I might, for the first time in 62 years give that a go but just wonder would it confuse the cars BMS which always charges at 14.8V on car overrun, my car too does very short runs but daily runs and I did see the SOC down to 73% (previous post) at one stage but it never affected the stop/start when I occasionally use it as circumstances dictate

Why should I get my battery load tested?, its working perfectly, in 62 years of car owenrship, all from new, I've never done this and have never used a battery charger/tender, all my previous cars charged at a constant 14.2/14.4V and all lasted "for ever", all the cars were in the family (handed down) for well over 20 years and none ever had a battery problem, I changed the battery on handing them down after 10/12 years purely as a precautionary measure. This is the first car I've owned with a smart charging system so I purchased a DVM which I leave permanently plugged in and occasionally glance at it, I will soon know if the charging system is acting up, if not, and the car fails to start then I will just go away and buy a new battery, so far, the indications seem to say that I should get, hopefully, at least 8 years+, I would be quite happy with this. I would suggest that a reasonable load test is to monitor the battery voltage with a multimeter connected across the battery terminals while someone starts the car. Assuming any car battery is charging properly then like ourselves, age kills them as their internal resistance keeps building up, I think this car's battery new resistance showed a VCDS resistance of ~ 2mohms, its presently a indicated around 7mohms,assuming a starter load of say 300A then the voltage drop will be 300*7/1000, 2.1V, to give a battery terminal voltage approx 10.3V, eventually, this volage drop on starting will either not pull in the starter solenoid or fail to crank the engine.

I have a Jan 2019 Polo with only ~ 23000 miles, all short runs, stop/start used selectively. The Battery SOC never exceeds 83%/85%, I have a DVM plugged into the internal power point which is quite reasonably accurate as checked with a accurate Multimeter, the voltage here always reads ~ 0.2V < than the battery terminal volts but is quite OK for checking charging pattern. The charging volts sits around 13.5V under normal driving but will always increase to 14.8V on the overrun. Recently when the SOC was only 73% I went on a round trip of 2hrs duration and the battery charged continuoisly at 14.8V for most of the trips duration but did fall to 13.5V about 15 minutes before reaching home. The "SOC 73%" scan was taken just before that trip but the "SOC 83%" scan wasnt taken until a month + ~ 530 miles later, the scans may be oft interest. What is interesting is that even with only a SOC of 73% the charging voltage/current fell from 14.96V/16.5A to 13.51V/2.2A in only 33 seconds, this with the car idling but once on the road continuously charged at 14.8V, BMS at its best for economy? SOC 73%.txt SOC 83%.txt

A VW Bora that was in the family for 22 years had a measured parasitic loss of 40mA, I used to regularly leave it at the airport for 10 days, total parasitic loss of 9.6AH, but never a problem in starting the car on return, right up to the time I replaced the battery after 12 years , purely as a precautionary measure as I was passing the car down to one of the children. A almost 21 year old Polo still in the family has always had a very high parasitic loss of 90mA for some reason or other, both these cars, like all VW pre smart alternators charged at a constant 14.2V. Have never measured the present car parasitic loss as I don't want to disconnect the battery to do so.

My DVM cost ~ £5 and also displays the interior temperature which most cars do not, even with all their fancy AC controls. I can leave it plugged in permanently as no parasitic loss because the ignition must be on to power the auxiliary power socket. Shortly before a 50 mile trip, VCDS showed a battey 73% SOC & "at rest" 12.4V, the DVM never fell below 14.1V until the ~ 1 hour trip was almost completed but then fell to 13.2V and VCDS then showed a 83% SOC and 12.6V "at rest".

"Comfort" coolant temperature gauges have been a feature of VW and VAG? group cars since at least 2000, the gauges do display numbers, 50C to 130C, they are supposed to roughly give a true reading up to 70C although my 2019 Polo seems to say, up to ~ 60C and will then rise rapidly to a constant 90C but will again read correctly from a alleged 107C, I did prefer the simple type which would sit under normal driving conditions right in the centre of the gauge, might only move by the thickness of the indicator and only moved up really in idling conditions until the rad fan cut in via its thermoswitch. I don't know what the thermoswitch settings are in this Polo but on another 2005 Polo are set..... Fan Speed 1 ON at 91C to 97C. OFF at 91 to 84C. Fan Speed 2 ON at 99C to 105C. OFF at 98 to 91C. Thermostat begins opening at 84C. Fully Open at 98C. VW Polo 2019 Coolant Temp VCDS/Car 52 /52 53/55 56/58 58/62 60/65 63/69 64/72 66/74 68/78 69/82 71/84 73/86 74/88 75/89 75/89

Can you just inhibit the Stop/Start for a few days or so, requires pressing the inhibit button each time you switch on the ignition but no big deal.

One of these Digital Volt Meters (DVM) that plug in to the auxiliary power socket give a permanently useful indication of battery voltage/Alternator smart charging etc.

The auxiliary (cigarette) power socket on mine is only live with the ignition on, not much use really, also the DRLs (daylight running lights) are then also on with a total battery demand of 4.8A. My £20 charger is a Ultimate Speed ULGD 5.0 C1 (5amps max) and has a volt meter, it seems reasonably smart, I attached it 2 hours after my 50 mile trip today, it read 12.8V and after switching on went to 14.4V for a few minutes and then settled at 13.5/13.6V trickle charge?. These type of chargers are really only battery tenders but should do the job quite well IMO to maintain any battery during infrequent car use.