Stop Start Problems

[Budweiser]

Hi all

2020 DB11 AMR V12.

Stop Start has a mind of its on resulting in it turning its self on and off intermittently.

Has anyone else experienced this?

I’m on a Timeless Warranty so will contact my dealer for help but prior knowledge of a know problem would be helpful.

I have a video of this happening which I will try and upload later.

[Caslad]

Don’t have stop-start on my DBS but the stop-start on the other cars tends not to work if the battery isn’t tip-top.

[Dewi 2]

Presumably your Stop/Start electronics are Mercedes-Benz.

I have noticed peculiarities with my new E-Class's stop/start.

Incidentally, I would always switch it off, if it did not have a completely silent starting system (motor/generator between engine and gearbox). I dont' want to repeatedly hear a gnashing of starter motor cogs with flywheel teeth.

Originally stop/start was working as expected. Foot off brake pedal and engine restarts. I then tried Economy Mode and ironically the stop/start ceased to operate. The Owners Manual said something about it not operating, unless all the 'required conditions' are being met.
Later, still in Economy Mode, the stop/start began working as expected again. Mystery.

Goodness knows what the 'required conditions' are, but I don't think we need to worry.
When in Economy Mode my car merrily cuts the engine on down hill inclines, but the only way to be aware that has happened, is to watch the tachometer. Does the DB11 have Economy Mode? I would guess not. Pointless really.

[pschlute]

Stop-Start requires a well charged battery to work. Cold weather also affects it.

[LTP]

First, a question. When you say "...turning its self on and off intermittently..." do you mean if you turn the system off in the menus, it just activates itself? Or do you mean that the system seems to operate intermittently when it's on? I believe some Stop-Start reset to "on" at every key-off, but if you turn it off it should remain off for the rest of that journey. If it is turning itself on mid-journey then that sounds like a fault. Intermittent operation is the norm, as has been said

My experience of Stop-Start is not with an Aston, but my Volvo V60 CC, so is not exactly applicable but I think is generic to the type. I believe the systems look at various parameters like the charge of the battery (the Volvo has a separate 48V Stop-Start battery - I don't know what the DB11 has); the temperature; the current draw by the car; etc. So my system seems to work when it feels like and, if I'm driving in slow, intermittently-moving traffic, after stopping the engine a few times it'll just cease working - probably because the battery charge has dropped. After a run to put some charge back, it'll recommence working.

If I bring the car to a halt with the footbrake and the engine stops and I then realise that it'll be a long delay like many people I'll often apply the electric parking brake. This additional spike of current will be detected by the system and sometimes it'll be enough to restart the engine, so I go from no engine and foot on the pedal to parking brake on and a running engine without the car having turned a wheel.

Hope this helps

[Budweiser]

Thank you all for replying.

I have a short video of what’s happening but for some reason can’t load it.

I generally turn the stop/start off as I don’t like it. So I start the car. Turn off the stop/start then start my journey The issue is that during the journey it will turn itself on and off repeatedly. While ON and I come to a stop it operates normally and cuts off the engine and restarts on request.

All very strange.

[M1AGM]

2019 AMR here and not had any issues with the stop/start not staying off.

[Budweiser]

Aston Martin are replacing the complete central unit under warranty. Two hours labour plus parts.

My thanks to Adam at Grange Aston Martin Brentwood.

[LTP]

Budweiser said:

Aston Martin are replacing the complete central unit under warranty. Two hours labour plus parts.

My thanks to Adam at Grange Aston Martin Brentwood.

Sounds like a result. Even MB tech can be fallible

[Dewi 2]

LTP said:

First, a question. When you say "...turning its self on and off intermittently..." do you mean if you turn the system off in the menus, it just activates itself? Or do you mean that the system seems to operate intermittently when it's on? I believe some Stop-Start reset to "on" at every key-off, but if you turn it off it should remain off for the rest of that journey. If it is turning itself on mid-journey then that sounds like a fault. Intermittent operation is the norm, as has been said

My experience of Stop-Start is not with an Aston, but my Volvo V60 CC, so is not exactly applicable but I think is generic to the type. I believe the systems look at various parameters like the charge of the battery (the Volvo has a separate 48V Stop-Start battery - I don't know what the DB11 has); the temperature; the current draw by the car; etc. So my system seems to work when it feels like and, if I'm driving in slow, intermittently-moving traffic, after stopping the engine a few times it'll just cease working - probably because the battery charge has dropped. After a run to put some charge back, it'lluu recommence working.

If I bring the car to a halt with the footbrake and the engine stops and I then realise that it'll be a long delay like many people I'll often apply the electric parking brake. This additional spike of current will be detected by the system and sometimes it'll be enough to restart the engine, so I go from no engine and foot on the pedal to parking brake on and a running engine without the car having turned a wheel.

Hope this helps

Does your Volvo 48 volt system comprise a starter/generator, situated between the engine and transmission?
ie. no conventional tooth operated starter motor, or belt driven alternator.
The Mercedes system has that technology and it does affect the operation of Stop/Start.
When in Eco Mode, unless certain conditions are continuously met, neither Coasting, nor Stop Start will be available all of the time.
One example of Stop/Start not operating, is when stopping at a junction without there being a vehicle ahead.
The engine does restart instantly, before the brake pedal pressure has been fully released. The odd thing being, nothing can be heard as the engine restarts.
If Brake Hold has been activated (heavy press on brake pedal), then the first touch on the accelerator pedal restarts the engine.

The DB11 might have Mercedes Stop/Start electronics, but not the 48 volt starter/generator, so the conditions parameters might not apply.

Edited by Dewi 2 on Wednesday 31st July 14:57

[LTP]

Dewi 2 said:

Does your Volvo 48 volt system comprise a starter/generator, situated between the engine and transmission?
ie. no conventional tooth operated starter motor, or belt driven alternator.
The Mercedes system has that technology and it does affect the operation of Stop/Start.
When in Eco Mode, unless certain conditions are continuously met, neither Coasting, nor Stop Start will be available all of the time.
One example of Stop/Start not operating, is when stopping at a junction without there being a vehicle ahead.
The engine does restart instantly, before the brake pedal pressure has been fully released. The odd thing being, nothing can be heard as the engine restarts.
If Brake Hold has been activated (heavy press on brake pedal), then the first touch on the accelerator pedal restarts the engine.

The DB11 might have Mercedes Stop/Start electronics, but not the 48 volt starter/generator, so the conditions parameters might not apply.

Hi David,

I'll be honest and to my shame as an engineer I've not really investigated the intricacies of my V60 - I regard it as a bit of an appliance compared to the V8V, which massively overlooks the uncomplaining way it performs as my daily, parked outside 24/7/12 so my Aston can live in the garage and taking to fields and tracks as well as tarmac with aplomb.

It does have a conventional-looking alternator driven by a poly-V belt, so I'm guessing it's not a starter generator but a separate starter motor system, probably with a reduction gear.
Skimming down your list of comparators:

• It will stop-start in Eco or Comfort mode. I don't tend to use "Polestar" much so I can't comment about that mode
• It only ever seems to enter "Coasting" mode when in Eco, but it seems to do that down any gradient if the speed is over 40mph and I've not applied the brakes. In "Coasting" mode the transmission is disengaged but the engine is still running.
• It will stop-start at junctions or in a queue, irrespective of cars in front or not
• Yes, the engine does restart before the footbrake is fully released. Or, if I've applied the park brake, as soon as I tap the throttle
• The engine restart sounds like a very quick "crank then fire" with virtually no hesitation
• I don't think the Volvo has "brake hold". But I'll stand on the brakes when stationary at a junction next time I'm in it to double-check.
• I can set the park brake to automatically engage every time the vehicle comes to a stop, but that is so bloody annoying as you can't crawl the car by lifting off the footbrake. So I've disabled it.
• When driving in slow traffic with the aircon on (as per the last few days in the UK), the stop-start will operate when I come to a halt in a queue and, after a short while, the car will restart the engine without me doing anything - I assume because of the electric loads on the battery(ies) or because it needs to push more fluid through the aircon to maintain the temperature

[Dewi 2]

LTP said:

Hi David,

I'll be honest and to my shame as an engineer I've not really investigated the intricacies of my V60 - I regard it as a bit of an appliance compared to the V8V, which massively overlooks the uncomplaining way it performs as my daily, parked outside 24/7/12 so my Aston can live in the garage and taking to fields and tracks as well as tarmac with aplomb.

It does have a conventional-looking alternator driven by a poly-V belt, so I'm guessing it's not a starter generator but a separate starter motor system, probably with a reduction gear.
Skimming down your list of comparators:

• It will stop-start in Eco or Comfort mode. I don't tend to use "Polestar" much so I can't comment about that mode
• It only ever seems to enter "Coasting" mode when in Eco, but it seems to do that down any gradient if the speed is over 40mph and I've not applied the brakes. In "Coasting" mode the transmission is disengaged but the engine is still running.
• It will stop-start at junctions or in a queue, irrespective of cars in front or not
• Yes, the engine does restart before the footbrake is fully released. Or, if I've applied the park brake, as soon as I tap the throttle
• The engine restart sounds like a very quick "crank then fire" with virtually no hesitation
• I don't think the Volvo has "brake hold". But I'll stand on the brakes when stationary at a junction next time I'm in it to double-check.
• I can set the park brake to automatically engage every time the vehicle comes to a stop, but that is so bloody annoying as you can't crawl the car by lifting off the footbrake. So I've disabled it.
• When driving in slow traffic with the aircon on (as per the last few days in the UK), the stop-start will operate when I come to a halt in

a queue and, after a short while, the car will restart the engine without me doing anything - I assume because of the electric loads on the battery(ies) or because it needs to push more fluid through the aircon to maintain the temperature

My experience of integrated starter/generators (ISG) is only very recent, but it does seem to be an interesting way of replacing the traditional starter motor, with a motor that can directly and silently rotate the crankshaft. Being able to fill-in for turbo lag with instant electrical torque and also act as an alternator by harvesting unneeded energy seems quite clever. If it can continue working as long as a traditional alternator, then I will be happy. This system does seem better suited to Stop/Start, because it is silent in operation and nothing is frequently trying to take chips out of a flywheel ring gear.

After a quick look on the internet for photos, it appears that Volvo are fitting ISGs to some of their models.
I understand that Mitsubishi Electric were one of the original ISG suppliers.
Mercedes just love fancy names for features and for ISG, they call it 'EQ Boost'.
I suppose that is better than their usual nomenclature, which usually ends 'tronic'

This photo shows a two cylinder engine, but it is just a representative exhibit. Mercedes have been fitting EQ Boost to many of their models for several years, including in-line 4, in-line 6 and I think the V8 engine used by AML (although no ISG for Aston).