I leave my car (Octy 1.4TSi DSG Elegance - Jan 2014 vehicle) to automatically stop and start in the engine, so when I come to halt and hold the brake down firmly the engine will stop. This has worked fine for most of the 2.5 years I've owned the car but recently (the past 2 months or so) I've had incidences of the the engine not actually starting, the starter motor has turned the engine over but the engine's coughed and not started. It recently had a full service (as per schedule) spark plugs, oil and filters etc. 

I'm wondering if this is an indication that the battery is on it's way out? I remember from my previous cars that the first sign of the battery dying was an occasional failure to start the engine and then a few weeks later it died. Anyone else had this experience?

Battery near end of life at 5 years sounds about right.

Not good, but par for the course.  

Obviously start stop improved fuel economy based on the engine not running, however I do wonder whether it's actually more economical overall...  it's got to put more wear on battery and starter motor, which aren't cheap items.  

Batteries died at 5 years before Stop / Start and also where people swith it off.

 

Plenty years of Stop / Start now and not many here or on social media reporting starter motor failure.

 

The engine stopped when stationary rather than running maybe for 30 minutes in a hours worth of gridlock traffic in a city does save me fuel and saves the emissions from my TDI / SCR with cheating devices to give false low emission figures.

 

Yeah, it likely depends massively on situation.

 

My start stop kicks in on my commute.  I'd say it's probably off for an average of 10 seconds each time.  

I have it off if it was going to just be 10 second stops.

When it takes 45 minutes to travel 8 miles i usually have stop / start on.  Switch is right there to activate or not.

Thanks everyone. New battery ordered.

38 minutes ago, Alex-W said:

Obviously start stop improved fuel economy based on the engine not running, however I do wonder whether it's actually more economical overall...  it's got to put more wear on battery and starter motor, which aren't cheap items.  

I always turn it off, mainly because I think it kills turbochargers.

Interesting belief, are turbo failure a major issue with Stop / Start turbo engines?

That must be why Private Hire Cars / Taxis keep the engine running.

 

But then Delivery drivers doing multi stops day after say might not leave the engine running and turbos are not failing left right and centre.

21 minutes ago, classic said:

I always turn it off, mainly because I think it kills turbochargers.

I have not considered this as the attention is on batteries and starter motors which have been beefed up for stop start mode. It cant do turbos much good stopping and spinning especially in heavy traffic. Can't do the main bearings good also.

Just as well they were designed to work that way and its just not all stop & no cooling.

Is sitting ticking over that much of a saviour of engines?

It may not be the battery. I find on my car that if the battery is low the stop / start system will not stop the engine, so it should not get to the point where it would need to re-start.

 

I wouldn't think it was a problem with the battery either because the system monitors the battery state of charge & will disable StopStart automatically when the battery is low.

A hot engine should be easy to restart (warm engine, warm battery & some time with the alternator runnung), its the first cold start that is heavy on the battery system.

 

Did you have the feeling that the starter motor speed is low when it fails to start?

If it splutters there's fuel going in.

 

How recently was the last service?

If it was only a few weeks ago, I'd take it back & explain the symptoms. They can easily check the battery (hopefully for free if they are nice).

Edited 15 October, 20196 yr by Gabbo

All the components used in stop start tech are significantly more robust than those of a decade or so ago. Stop start won't knacker an engine or its bolt ons by itself.

 

The AGM and EFB batteries are specifically built for the cyclic stop start applications and switched charging of smart alternators. They cope very well with that sort of loading cycle, its one of their benefits. On an average duty cycle covering the 95th percentile of vehicle users, they will last 10 years/100,000miles.

 

However, they don't last as long if deep discharged regularly, are kept at a relatively low voltage for long periods of time or if they are overheated or overcharged, the same with any lead acid battery.

 

And if there has been a significant period of discharge in the batteries lifetime be it from long storage times in the factory or at a dealership, then the lifespan will be compromised and it will fail early. The longer the discharge time, the shorter the battery life. It only takes one decent time period of abuse for irreversible damage.

 

I'm just waiting for someone who has disconnected the battery minder to inhibit stop start to have their AGM battery dry out from overcharging as the programming won't know whats going on and keeps the alternator on max output. Dry batteries go pop!

Edited 15 October, 20196 yr by BigEjit

Get the car scanned with VCDS. As said by a few above, a warm engine should start easily, so there's likely a fault in some other system than the battery.

5 hours ago, Roottootemoot said:

Interesting belief, are turbo failure a major issue with Stop / Start turbo engines?

That must be why Private Hire Cars / Taxis keep the engine running.

 

But then Delivery drivers doing multi stops day after say might not leave the engine running and turbos are not failing left right and centre.

Shouldn't be on a problem on TSi engines as the turbo is water cooled be the secondary water pump which is electrically driven, as the ignition is on then the secondary water pump will still be working. Not to sure on the TDi's though.

 

As has been said also battery's and starter motors are a lot more robust then vehicles with out stop/start.