My dad phoned me today to tell me that the main battery on his 21 plate Karoq had gone completely flat , he has been having KESSY issues of recent ,not sure if it’s related, I suspect a battery drain, anyone got ,or had similar issues? 

All these electronics that shut down only to a standby level seem to drain quite a lot. KESSY, especially, is a relatively high load and that's why the passenger door handle shuts down by design after about three days of inactivity.

 

Another problem is the fact that the alternator won't charge the battery to full unless it can do that last part without causing extra fuel consumption, i.e. on deceleration or while going downhill.

 

I have a voltmeter connected permanently so that I can read the display through the closed driver's window. Turns out that after about five days of rest the voltage drops to 12.4, where sulfation starts to deteriorate the battery, so at that point I connect it to my external charger.

 

Edited 8 March, 20224 yr by agedbriar

There were a lot of cases of dud batteries around in 2019/20. Often caused by a manufacturing issue and allowing cars to stand for months due to Covid shutdown. This affected VW and Audi cars as well using the same one needed with stop start fitted. If the battery is allowed to go completely flat it may never recover completely. Some just failed anyway.
My August, hence 20 reg car, had to have a new battery in the first week as it wouldn’t charge fully.

You may have a less affected battery that has been able to charge slightly and hence it has managed to now.

I suspect I have a low battery as well, stop/start rarely kicks in. I got the car in Dec 20 and because of Covid couldn't drive it much so it had a bad start in life. Now most of my journeys are short also. After it had come back from the dealer for something else recently Start/Stop was kicking in loads so I guess they charged the battery for me, but quickly it went back to its normal of not doing it unless I do a much longer journey. When the battery is nicely charged the speed/smoothness of the re-start is much better also, when it's low the re-starts can be downright sluggish and dangerous sometimes.

6 hours ago, FireBIade said:

I suspect I have a low battery as well, stop/start rarely kicks in. I got the car in Dec 20 and because of Covid couldn't drive it much so it had a bad start in life. Now most of my journeys are short also. After it had come back from the dealer for something else recently Start/Stop was kicking in loads so I guess they charged the battery for me, but quickly it went back to its normal of not doing it unless I do a much longer journey. When the battery is nicely charged the speed/smoothness of the re-start is much better also, when it's low the re-starts can be downright sluggish and dangerous sometimes.

My stop/start rarely kicks in. I have only done 15,000 miles in just over three years. Most of my journeys are under 3 miles (not in a city).  I'm not particularly bothered by it.

 

tom

Not driven our Karoq for nearly two weeks. Stop/start worked first time.

Good battery then

My stop start will stop any chance it get's, if I forget to disable it, even with a cold engine that's travelled less than a mile it stops !

At it's 3 year service the dealer noticed that my battery was faulty and replaced it under warranty

I hadn't had or noticed a problem with it so happy with the dealer for doing it.

Probably one of the faulty batch.,

On 08/03/2022 at 22:56, agedbriar said:

All these electronics that shut down only to a standby level seem to drain quite a lot. KESSY, especially, is a relatively high load and that's why the passenger door handle shuts down by design after about three days of inactivity.

 

Another problem is the fact that the alternator won't charge the battery to full unless it can do that last part without causing extra fuel consumption, i.e. on deceleration or while going downhill.

 

I have a voltmeter connected permanently so that I can read the display through the closed driver's window. Turns out that after about five days of rest the voltage drops to 12.4, where sulfation starts to deteriorate the battery, so at that point I connect it to my external charger.

 

My (wife's) 3 year old Polo which only does very short runs (< 15,00kms in 3 years)  generally shows ~ 79 to 82% SOC (VCDS), she never enables stop/start (disables it at ignition on)  I only replaced her last Polo's (a 2005 9N) battery after 12 years, purely as a precautionary measure as daughter was/ is still driving it, of course all the pre smart BMS/alternator charged at a constant 14.1/14.3 volts so will be interesting to see how this variable energy saving/regenerative charging pans out.

 

Re parasitic losses: Can't comment on modern car demands but on at least 6 different family (VW) cars that I checked for the parasitic loss with a multimeter connected between the disconnected earth strap and battery negative terminal, all, apart from the 9N Polo, drew 40 to 60 ma, the 9N, from new,  drew, and still does, almost exactly 95ma but right up to the time of the battery change was regularly left at the airport for 10 days or so which means the consumed AH were ~ 23AH, a fair whack by any standards, but car still started no problem.

 

You say that your car battery voltage falls to 12.4V after 5 days which is around 72% SOC, assuming that the external charger gets the SOC to 100% (12.7V?). You are losing 28% SOC so (if) a 70AH battery will have lost 19.6AH so parasitic loss is 160ma?. Quite possible but I would be mildly surprised if todays cars have a parasitic loss of > 100ma. Unfortunately, because present car has DRLs which draw 4.4A, I can't measure the parasitic loss with VCDS. 

Edited 12 March, 20224 yr by Johngerard

7 hours ago, vulcan said:

My stop start will stop any chance it get's, if I forget to disable it, even with a cold engine that's travelled less than a mile it stops !

 

Yes, very  very hard to see how any savings accrue when stop/start operates with a stone cold engine, "less than a mile" on mine is exactly 0.5kms despite the manual clearly stating that the car must reach a minimum temperature before S/S is enabled. Despite all this I use it as I see fit and it doesn't annoy me in the slightest, Perhaps, like cruise control, adaptive stop/start will soon be ours?, why not, especially if one does the same run to work or whatever, every day, where traffic congestion etc will be simillar, the learning curve is easy.

7 hours ago, Johngerard said:

My (wife's) 3 year old Polo which only does very short runs (< 15,00kms in 3 years)  generally shows ~ 79 to 82% SOC (VCDS), she never enables stop/start (disables it at ignition on)  I only replaced her last Polo's (a 2005 9N) battery after 12 years, purely as a precautionary measure as daughter was/ is still driving it, of course all the pre smart BMS/alternator charged at a constant 14.1/14.3 volts so will be interesting to see how this variable energy saving/regenerative charging pans out.

 

Re parasitic losses: Can't comment on modern car demands but on at least 6 different family (VW) cars that I checked for the parasitic loss with a multimeter connected between the disconnected earth strap and battery negative terminal, all, apart from the 9N Polo, drew 40 to 60 ma, the 9N, from new,  drew, and still does, almost exactly 95ma but right up to the time of the battery change was regularly left at the airport for 10 days or so which means the consumed AH were ~ 23AH, a fair whack by any standards, but car still started no problem.

 

You say that your car battery voltage falls to 12.4V after 5 days which is around 72% SOC, assuming that the external charger gets the SOC to 100% (12.7V?). You are losing 28% SOC so (if) a 70AH battery will have lost 19.6AH so parasitic loss is 160ma?. Quite possible but I would be mildly surprised if todays cars have a parasitic loss of > 100ma. Unfortunately, because present car has DRLs which draw 4.4A, I can't measure the parasitic loss with VCDS. 

I should have mentioned that the five days of rest required to drop to 12.4 V are after a standard 35 km trip to the shopping centre, with start/stop disabled but with the last leg of the trip going uphill.

Also, the permanent voltmeter consumes 8 mA on its own.

Is the Karoq battery a standard Lead acid type or something designed to handle lower charge rates?

On occasions when the car has been idle for a week or so if the voltage is measured at the auxiliary socket before starting it has been as low as 11.9 volts but has never failed to start. All journeys are usually  at least 50 miles.

Car 2018 SEL now 22k miles.

It’s not a standard lead acid battery. I have a suitable charger and it has to use a special mode when charging the fitted stop start battery. You must not use a conventional old style charger.

Edited 12 March, 20224 yr by kenfowler3966

44 minutes ago, Karock said:

Is the Karoq battery a standard Lead acid type or something designed to handle lower charge rates?

On occasions when the car has been idle for a week or so if the voltage is measured at the auxiliary socket before starting it has been as low as 11.9 volts but has never failed to start. All journeys are usually  at least 50 miles.

Car 2018 SEL now 22k miles.

Hi Karock, your battery will be either EFB or AGM. Performance of AGM is supposed to be superior.

2 hours ago, Karock said:

Is the Karoq battery a standard Lead acid type or something designed to handle lower charge rates?

On occasions when the car has been idle for a week or so if the voltage is measured at the auxiliary socket before starting it has been as low as 11.9 volts but has never failed to start. All journeys are usually  at least 50 miles.

Car 2018 SEL now 22k miles.

 

Mine, just now, after standing overnight, is 12.18V at the battery terminals (DRLs off) and 12.1V both at the auxiliary socket and the battery terminals with ignition on (and DRLs on) so ~ 55% SOC, yours has ~ 43% SOC, strictly speaking, the battery voltage should be taken open circuit, the last VCDS reading (24th Jan) shows a alleged 79% SOC.The DRLs woul be on when taking the VCDS log as the ignition must be on, I don't know how it calculates the "at rest" voltage which presumably is a calculated open circuit voltage.

 

4:58:57 24/01/2022 14,154kms Engine OFF

  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

 

 

 

 

At Rest (Open Circuit) Battery Voltage

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

Edited 12 March, 20224 yr by Johngerard

Thanks, an Interesting analysis.

This morning The voltage at the auxiliary socket was down to 11.4 volts but the car started immediately.  A normal lead/acid battery wouldno doubt  have failed if it dropped this low.

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.

Edited 13 March, 20224 yr by Johngerard

8 hours ago, Karock said:

Thanks, an Interesting analysis.

This morning The voltage at the auxiliary socket was down to 11.4 volts but the car started immediately.  A normal lead/acid battery wouldno doubt  have failed if it dropped this low.

 

Can you check the charging voltage immediately after start up, I think mine charges for a minute or two at 15V on start up and then falls to ~ 12.8ish and will then only charge at up to 15V on the overrun, one would think though that with a voltage as low as 11.4v, approx 10% SOC,  that it would "smartly" charge at a much higher voltage than the normal energy saving ones.

 

I did check the charging voltage and after a few seconds it was at 14.8 volts. Unfortunately only a short run this morning so could not tell if it reduced later.

I shall be driving to the East coast ( about 70 miles) later in the week so will take some more measurements then.

 

 

To properly derive the battery state of charge from its voltage, the latter must be measured with the battery in a no-load state.

 

Through the closed window of my KESSY Karoq, which has been resting for several hours, I can read the internal voltmeter displaying 12.6 V. When I only unlock and open the driver's door, the voltage drops to 12,2 V in a few seconds. While the first reading is questionable, the second reading is definitely useless for SOC determination.

 

Edited 13 March, 20224 yr by agedbriar

34 minutes ago, agedbriar said:

To properly derive the battery state of charge from its voltage, the latter must be measured with the battery in a no-load state.

 

Through the closed window of my KESSY Karoq, which has been resting for several hours, I can read the internal voltmeter displaying 12.6 V. When I only unlock and open the driver's door, the voltage drops to 12,2 V in a few seconds. While the first reading is questionable, the second reading is definitely useless for SOC determination.

 

 

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.

24 minutes ago, Johngerard said:

 

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.

 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.

Edited 14 March, 20224 yr by Johngerard

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.

After opening the bonnet and locking the car, you should wait at least 15-20 min for all the systems to go into standby again and the battery recovers, so you get the maximum voltage reading.

 

Edited 14 March, 20224 yr by agedbriar