Start/Stop

[glj81]

Hi all,

Not usually a fan of start/stop but finding it more bearable in the A5, possibly because the petrol engine responds faster.

In any case, it has cut in a couple of time when lifting off at speed - is that normal?! I was on the motorway yesterday and lifted from ~70mph and the engine cut.

Main improvement has to be the fact it knows the car in front has moved in traffic and it doesn't seem to kick in on roundabouts either. It was infuriating on the Q3.

Still prefer to switch off mind.

 

[cuke2u]

Yes I believe this is part of the mild hybrid system. I also find it isn't intrusive with my car, maybe the stronic also smooths things out as well. Just slip the box into sport, that disables the start stop as well...

 

[S32B]

wow didn't know this, sounds a bit dangerous!

I now always push the off button for it when I get in the car, first thing I do after pushing the start button A few times I'd rolled up to a junction and whilst still moving it cut out, only for me to push the go pedal a split second later.

 

[JonChalk]

In any case, it has cut in a couple of time when lifting off at speed - is that normal?! I was on the motorway yesterday and lifted from ~70mph and the engine cut.

It's called "Intelligent Coasting", it can happen in any mode except "S" (or Manual, I think ) - I'm in Dynamic all the time and it still happens.

The post in the link below tells you how to turn it off, if you don't like it.

#14

 

[b0k]

Not sure why you would want to turn Intelligent Coasting off as it only kicks in under certain coasting conditions and works well to save fuel when you don’t need the engine. If you’re driving hard it’s not going to kick in, and it starts again near instantaneously. All assistance systems are active and run by battery. This isn’t Mild Hybrid, it came in about a year and a half ago when they introduced Ultra to the A5.

When I looked at it a while back Mild Hybrid was going a step further where energy stored in larger 48V battery from braking, and the wheels are driven under light load by small electric motors. I haven’t looked into this for a while so may have changed, but that’s only available when the car electrics go from 12V to 48V.

 

[cuke2u]

https://en.wikipedia.org/wiki/Mild_hybrid

 

[L_G]

I thought intelligent coasting was when the auto gearbox selected neutral rather than the engine cutting out?

 

[b0k]

It’s more than just neutral, the system decides if it selects neutral and also cuts engine. Car can also disconnect the drive shaft on Quattro (at both front and back making it a 2WD) - this is what they were calling Ultra a while back. Before that they did coast but without the engine cutting out. I have had A5s with both systems. There are videos showing how this all works. It’s not what Audi call MHEV as I understand it. Just keeps all driver and power assistance systems running on battery while engine off, not really a hybrid. The alternator is reversed and starts the engine when coasting, rather than the starter motor which is only used for stationary starting.

The Wikipedia article is quite generic. Here is an Audi MHEV one with more detail. I thought there was a separate drive motor but had a quick look at this and looks like it’s a beefed up starter alternator BAS that can e.g. actually drive the car when parking or maintain coasting. Also looks like the 4 cylinders keep 12V, others get 48V.

https://www.audi-mediacenter.com/en...ile-and-efficient-mild-hybrid-technology-8761

 

[cuke2u]

Yes there are now hybrids that combine the alternator and starter in one unit. Also, in mild hybrids, this can be used to aid the start stop system.
More about the coasting systems and it being part of the MHEV here https://auto.howstuffworks.com/fuel-efficiency/hybrid-technology/idle-stop-system1.htm

 

[L_G]

It’s more than just neutral, the system decides if it selects neutral and also cuts engine. Car can also disconnect the drive shaft on Quattro (at both front and back making it a 2WD) - this is what they were calling Ultra a while back. Before that they did coast but without the engine cutting out. I have had A5s with both systems. There are videos showing how this all works. It’s not what Audi call MHEV as I understand it. Just keeps all driver and power assistance systems running on battery while engine off, not really a hybrid. The alternator is reversed and starts the engine when coasting, rather than the starter motor which is only used for stationary starting.

The Wikipedia article is quite generic. Here is an Audi MHEV one with more detail. I thought there was a separate drive motor but had a quick look at this and looks like it’s a beefed up starter alternator BAS that can e.g. actually drive the car when parking or maintain coasting. Also looks like the 4 cylinders keep 12V, others get 48V.

https://www.audi-mediacenter.com/en...ile-and-efficient-mild-hybrid-technology-8761

That article mentions the A8/Q8 rather than B9 platform. The observed behavior of my 2018 S5 is the same as described in the below article;

https://www.audi-mediacenter.com/en...-audi-a4-and-a4-avant-4328/transmissions-4337

 

[glj81]

Thanks for all the comments guys, glad it's 'normal'.

I still find myself turning it off though, not a fan with an auto box, but def better than it was on the Q3 (also auto).