Battery or alternator issue?

[Jondalar]

My 2018 Alltrack Wolfsburg (First reg 28 Feb 201 has 50k on it and lately I've noticed that the start stop won't allow the engine to stop when at traffic lights etc. I thought this was because of driving less due to Covid19 but even doing over 90km in a day (over half hhighway running) 3 days straight it is still not allowing the engine to stop. The centre unit says "Power consumption is high" when all I have on is the HVAC on auto and the stereo. I was at the dealer for another issue and asked them to check, they said the battery is fine but "needed charging" which they put onto a fast charger for 15 min and then it allowed the stop start. I drove 70km highway home and then two days later drove to work and stop start was normal, however the following two days (with 100km each day driven) the start stop is refusing again. Surely either the battery or alternator isn't working well?

[zzc2010]

My 2018 Alltrack Wolfsburg (First reg 28 Feb 201 has 50k on it and lately I've noticed that the start stop won't allow the engine to stop when at traffic lights etc. I thought this was because of driving less due to Covid19 but even doing over 90km in a day (over half hhighway running) 3 days straight it is still not allowing the engine to stop. The centre unit says "Power consumption is high" when all I have on is the HVAC on auto and the stereo. I was at the dealer for another issue and asked them to check, they said the battery is fine but "needed charging" which they put onto a fast charger for 15 min and then it allowed the stop start. I drove 70km highway home and then two days later drove to work and stop start was normal, however the following two days (with 100km each day driven) the start stop is refusing again. Surely either the battery or alternator isn't working well?

It happened 2 times to my Golf and Passat. That’s the indication of dead batteries. Have your battery checked mate.


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[Jondalar]

I had the battery checked by the dealer, they said it is fine... (which I don't believe but hard to argue with)

[Lucas_R]

The car is programmed so that if voltage is below a certain amount (i believe its set to 12.5v or thereabouts) then the start/stop system will not kick in. A healthy battery (when engine is running) should be putting out between 13.5-14.5v, and approx 12.6v or slightly higher when engine is not running.

My money is on a failing battery, although in saying that, your car is only 2-3yrs old and should have an AGM battery for the start/stop system - so perhaps the battery is faulty rather than simply dying due to age/use. Take it to a battery shop (eg Batteryworld) and they can check the battery properly.

Failing batteries also tend to cause weird electrical issues on modern cars, so if anything odd starts happening then this will be further evidence of a battery problem.

[Transporter]

My 2018 Alltrack Wolfsburg (First reg 28 Feb 201 has 50k on it and lately I've noticed that the start stop won't allow the engine to stop when at traffic lights etc. I thought this was because of driving less due to Covid19 but even doing over 90km in a day (over half hhighway running) 3 days straight it is still not allowing the engine to stop. The centre unit says "Power consumption is high" when all I have on is the HVAC on auto and the stereo. I was at the dealer for another issue and asked them to check, they said the battery is fine but "needed charging" which they put onto a fast charger for 15 min and then it allowed the stop start. I drove 70km highway home and then two days later drove to work and stop start was normal, however the following two days (with 100km each day driven) the start stop is refusing again. Surely either the battery or alternator isn't working well?

Recharge your battery, as most likely the voltage during engine cranking is down to bellow 7.6V just for milliseconds and this is the threshold set up from manufacturer for the SS system to stop working.

[DV52]

My 2018 Alltrack Wolfsburg (First reg 28 Feb 201 has 50k on it and lately I've noticed that the start stop won't allow the engine to stop when at traffic lights etc. I thought this was because of driving less due to Covid19 but even doing over 90km in a day (over half hhighway running) 3 days straight it is still not allowing the engine to stop. The centre unit says "Power consumption is high" when all I have on is the HVAC on auto and the stereo. I was at the dealer for another issue and asked them to check, they said the battery is fine but "needed charging" which they put onto a fast charger for 15 min and then it allowed the stop start. I drove 70km highway home and then two days later drove to work and stop start was normal, however the following two days (with 100km each day driven) the start stop is refusing again. Surely either the battery or alternator isn't working well?

Jon: Hi
Here's a bunch of prerequisites that must be satisfied for SS to successfully stop the engine

• The vehicle is stationary (speed = 0km/h).
• The engine speed is below 1200rpm.
• The coolant temperature is between 25°C and 100°C.
• The brake vacuum is more than 550mbar.
• The energy required to restart the engine that was calculated before “engine off” can be supplied by the battery (starting voltage prediction).
• The battery temperature is greater or equal to -1°C and less than 55°C.
• The air-conditioning requirement of the occupants is not too high.
• The difference between target and actual vent temperature is below 8°C.
• The diesel particulate filter is not in regeneration mode (diesel engines only).

Please note that these are "AND" conditions - so ALL the thresholds above must be met before SS is operational! It's no wonder that SS doesn't always operate as expected - if you like SS (I don't)

Incidentally, if you are charging the battery - make sure that you don't connect the negative charger lead directly to the negative battery post; ALWAYS use the special "up-stand" facility near the battery (see below), or connect the negative charger lead to a bolt on the car body



Don

[dArK5HaD0w]

The exact same thing happened with my 3 yr old Superb.
The battery was "fine", but I noticed in the past few weeks that start-stop wouldn't actually kick in to turn off the engine while stopped.

Didn't think of it much.

When my car was in for its 45k km service last week, I asked them to check the battery as these VWAG start-stop batteries r notorious to start failing after 2.5 to 3 yrs.

Turns out the battery was on its way out, so they replaced with a new battery for free, being under warranty.

Win win.

Turns out the start-stop not behaving was an early sign of the battery starting to die.

[achk]

My Passat 206 battery died after 2.5 years. It was replaced by VW roadside assistance free of charge (covered by warranty). I don't believe mine was fitted with an AGM battery ex factory. Prior to dying, the stop start feature stopped too but i didn't take too much notice until the car wouldn't start one day.

[Jondalar]

Hi All,
Thanks for the helpful replies. I found that after three days consecutive driving to work and back (100km each) it finally stopped at the lights, but then after 3 or so times it refused again. Is a normal old battery charger OK?

Thanks,
Karl

[Lucas_R]

Hi All,
Thanks for the helpful replies. I found that after three days consecutive driving to work and back (100km each) it finally stopped at the lights, but then after 3 or so times it refused again. Is a normal old battery charger OK?

Thanks,
Karl

If its a really old charger then no - you will need something like this which is a smart charger and is made for modern cars and start/stop batteries. This is the one i have that i have used for about 4-5 years now: CTEK MXS 5.0 (12V 5A) Battery Charger MXS5.0 | Sparesbox

Or this more powerful 7amp model: CTEK MXS 7.0 (12V 7A) Battery Charger MXS7.0 | Sparesbox

Get a 5amp model or higher. Any less than 5amp is pretty much useless.

I still think your battery is dying - it should not be causing issues if you are driving 90-100km each day.

[Ozsko]

Have you noticed that in all cases the problem has arisen since colder weather has arrived and mine is no different. Batteries deliver less in colder weather.

[Micky 32]

My Feb 2017 Passat has an AGM battery. I noticed last winter i began to see “power consumption too high” intermittently especially in low ambient temperatures but for most part start stop worked ok. It never happened the previous winters. I was also getting a glitch where on the first start of the day the heated steering wheel would switch itself on after it cranked. I presume it’s a weakening battery but since the summer has started it’s being behaving fine.

[Micky 32]

I asked them to check the battery as these VWAG start-stop batteries r notorious to start failing after 2.5 to 3 yrs.

.

I bought one of those bluetooth battery monitors and it’s quite interesting how the charging system works on these cars, not surprising your above comment. The car seems to depend more on the battery than the alternator. It only seems to charge the battery when it needs it. The alternator mostly puts full output out when de accelerating/braking. The logged charging graph on the bluetooth monitor goes up and down during the drive especially on country roads where you accelerate and brake for corners. That means the battery is working harder than older cars where the alternator keeps batteries fully charged at all times.

The bluetooth monitor also records cranking voltage. It recorded a low voltage crank of 8.9volts this morning on first crank of the day. Outside temp was a mild 16 degrees C.

[zzc2010]

I bought one of those bluetooth battery monitors and it’s quite interesting how the charging system works on these cars, not surprising your above comment. The car seems to depend more on the battery than the alternator. It only seems to charge the battery when it needs it. The alternator mostly puts full output out when de accelerating/braking. The logged charging graph on the bluetooth monitor goes up and down during the drive especially on country roads where you accelerate and brake for corners. That means the battery is working harder than older cars where the alternator keeps batteries fully charged at all times.

The bluetooth monitor also records cranking voltage. It recorded a low voltage crank of 8.9volts this morning on first crank of the day. Outside temp was a mild 16 degrees C.

That’s the blue technology. Energy regenerating. Pleasure to see the technology working well, however, the batteries were gone faster than usual. Prefer the old fashions.


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[Micky 32]

Got one of those Topdon battery conductance testers.

My AGM battery is 3 1/2 years old (160,000km).

For comparison i tested my battery against my friends new car battery.

My battery Varta AGM 680 A en , 68 ah:

State of health : 54%

Measured amps : 500A ( rated 680A)

Interestingly the report is “Good Battery”

Friends battery Varta EFB+ 700A en, 70ah

State of health : 100 %

Measured amps : 815A ( rated 700A).

It seems these battery don’t last long , probably due to stop/start and the car keeping the battery at 80% charge.