EV Discussion thread

JKenH

I’ve been following this story on Facebook and mgevs.com and the general opinion is that this story is BS. It may well be but, if it were true, how would any of us feel if we were the driver and everyone was so dismissive of what would have been a quite harrowing situation and a genuine cause for concern. 

If there was an electronic failure then it is just possible with the right knowledge and experience a driver could have safely brought the vehicle to a halt but in charge of a runaway vehicle how many of us would be able to think calmly and logically? Some would but then there wouldn’t have been much of a story to report. As for it being a stunt, would you involve the police and crash your car into their vehicle, knowing there was a good chance that they might take a close look at your car to check the story out?

It’s ok to be suspicious but what surprises me is just how dogmatic some people can be on social media (that they are right).

1961Nick

The brakes are hydraulic & not fly by wire so enough pedal pressure would stop a 200bhp vehicle even without servo assistance.

Martyn1981

Netexporter said:

JKenH said:

Netexporter said:

Definitely operator error, IMO, plus poor reporting.

Poor reporting (with the terminology) but what leads you to conclude it was definitely operator error? 

Well for a start there's the pilots' maxim; aviate, navigate, communicate. In an emergency situation, those are your priorities, in that order, otherwise you are liable to information overload, which is detrimental to performance. The driver seems to have managed to make numerous phone calls.

I find it hard to believe the brakes weren't functional. They are just standard hydraulic brakes, the same as you'd find in any car. They have dual circuits, so multiple failure is unlikely. Even if the braking assistance was disabled you can still stop the vehicle if you press the pedal hard enough. I suppose most drivers, these days, haven't any experience of actually having to supply all the muscle to stop.

That's interesting about the brakes. I was thinking it could be a weird computer failure as it was new, so some freak event, but if the brakes can work then that changes things. I also couldn't get my head around the bit that the vehicle had slowed to 15mph, so that means something was happening.

Am I going mad, or did a story like this make the news, perhaps 10yrs ago, with a lorry driver? I seem to recall something about a long motorway incident, the driver refusing to turn the engine off, as he'd lose the brakes and steering. If I'm not making this up, and there's a good chance this is a pre-coffee, morning hallucination, then the driver was eventually prosecuted for faking it.

I think there have been a small number of freak events with a cruise control module, again going back a decade or more, where it could be accidentally activated, but the cause of activation so rare, hard to track down. With the cruise on, but not 'really on', then braking didn't deactivate it, as it ..... well ..... didn't know it was on. I may be mixing up stories, but I think a car company (possibly Ford) produced a vid showing that a car with the cruise jammed on, could still be stopped by mechanical brakes. However, the judge was suspicious as to the lack of sound in the video, and when they admitted there was sound, and supplied it, the test driver can be heard shouting that he's applying over a 100lb of pressure to the brake pedal (I forget the exact amount), which the judge doubted that all drivers could manage.

Then there's unintended acceleration, but this is typically seen when a car starts off, and probability tends to rise in line with drivers age, so seems to be a case of hitting the accelerator instead of the brake by mistake. I think in the case of Tesla's, such events have been confirmed (wrong pedal) by checking the data.

I hope this new news story is fake, as MG are really doing well (compared to other Chinese and European companies) so don't need any false bad press.

JKenH

1961Nick said:

The brakes are hydraulic & not fly by wire so enough pedal pressure would stop a 200bhp vehicle even without servo assistance.

But how much is enough? 

In theory brakes will work if the brake servo fails (electric rather than vacuum on EVs) but it isn’t the same as driving a non servo’d car like we all probably have done in the past. Because of the servo assistance the brake pedal has a shorter lever than a non servo car so (probably 50% or so) more pedal pressure will be required to stop the car than with a non servo car. The other thing to bear in mind is that the modern cars we drive are probably twice the weight of the ones we drove in our youth with non servo brakes. EVS are heavy and without a brake servo will be very difficult to stop. We forget just how bad non servo’d brakes were. 

This wasn’t a sudden incident where the driver hit the wrong pedal - it reportedly went on for some 15 minutes. If the cruise control had jammed on (or for whatever other reason the car was trying to maintain a constant speed) then as the driver brakes the motor will presumably provide more torque to overcome the retardation the brakes are trying to apply. Continued application of the brakes in this situation will cause them to overheat and boil the brake fluid. (This happens frequently if you take a car with standard brake fluid on a race track and drive it hard.)  Once the fluid boils application of the brake pedal simply compresses the vapour in the brake lines and produces little or no retardation. You can get some stopping power by pumping the brake pedal but if you haven’t experienced it you might not think to do that.

I still don’t know quite what to make of it. I think the general trend is to discredit the story for whatever purpose. Several reasons have been given why the story might be untrue. I don’t know if or why the car genuinely refused to slow down but wanted to give one possible explanation why the driver, in that situatio, could have become a passenger unable to bring the car to a halt. 

michaels

I have a recall on my nissan leaf: Nissan has identified a concern affecting the Vehicle Control Module (VCM) software logic following routine internal testing.  In specific and rare circumstances, after switching off cruise control and then within a certain timeframe changing the drive mode whilst quickly applying the throttle there is a possibility of temporary unintended acceleration.

So not out with possibility that there was a software error.

Plus there is software between the brake pedal and the braking power applied as lower levels of braking are intercepted and regen is applied, when the battery is 100% more brake travel is needed to get retardation so there is not simply a direct link from the brake pedal to the brakes anymore.

I think on the leaf there is a way to put the transmission into N whilst in motion but I never use it so would not know how to do it off the top of my head despite 9 years of ownership and 80k miles driven.

Agree the driver probably could have achieved a stop by stomping hard enough on the brake pedal (until the fluid boiled anyway) but if the car was determined to try to maintain 30mph that sounds pretty difficult, no idea if there is a mechanically operated handbrake on a ZS or simply an electronic switch that no doubt can not be engaged if the vehicle is in motion.  There is also probably like on the leaf a way to select neutral but the driver likely wouldn't know how to and it would also no doubt involve electronics which might not be active if there were some major ECU failure,  Thee is obviously no way to 'stall out' the engine and I suspect no way top switch off the car whilst in option (as this would be dangerous).

So not impossible with enough ECU fails for the only way to stop the vehicle being unassisted breaking vs a 173bhp motor.

noitsnotme

The ‘victim’ appears to have posted here but unsure if it’s really him - https://www.mgevs.com/threads/interesting-worrying-story-from-scotland-zs-with-no-brakes.13818/

He’s only posted once and not come back to answer questions from other MG ZS owners.

A few points raised such as why do the pictures of him posing by his car afterwards show no damage from it hitting the police van twice.

Someone states he has form for this sort of thing.  And another claims to have known him 15 years ago posted this…

”actually used to know this guy about 15 years ago, and back then he had a reputation for bizarre and extreme tall stories. It was like he lived in some sort of fantasy world or told these stories for attention, then later would take great pleasure in telling people it was all just a big joke.”

The plot thickens.

noitsnotme

michaels said:

I have a recall on my nissan leaf: Nissan has identified a concern affecting the Vehicle Control Module (VCM) software logic following routine internal testing.  In specific and rare circumstances, after switching off cruise control and then within a certain timeframe changing the drive mode whilst quickly applying the throttle there is a possibility of temporary unintended acceleration.

So not out with possibility that there was a software error.

Plus there is software between the brake pedal and the braking power applied as lower levels of braking are intercepted and regen is applied, when the battery is 100% more brake travel is needed to get retardation so there is not simply a direct link from the brake pedal to the brakes anymore.

I think on the leaf there is a way to put the transmission into N whilst in motion but I never use it so would not know how to do it off the top of my head despite 9 years of ownership and 80k miles driven.

Agree the driver probably could have achieved a stop by stomping hard enough on the brake pedal (until the fluid boiled anyway) but if the car was determined to try to maintain 30mph that sounds pretty difficult, no idea if there is a mechanically operated handbrake on a ZS or simply an electronic switch that no doubt can not be engaged if the vehicle is in motion.  There is also probably like on the leaf a way to select neutral but the driver likely wouldn't know how to and it would also no doubt involve electronics which might not be active if there were some major ECU failure,  Thee is obviously no way to 'stall out' the engine and I suspect no way top switch off the car whilst in option (as this would be dangerous).

So not impossible with enough ECU fails for the only way to stop the vehicle being unassisted breaking vs a 173bhp motor.

Apparently you can apply the electronic parking brake while it’s moving.  According to another forum the manual says…

”Emergency Braking Function
If whilst driving the vehicle there is a footbrake failure, the vehicle can be decelerated by pulling up and holding EPB switch.”

Although how many owners read the manual and would know this.

I’m quite ocd with manuals and read the Tesla one (virtual) cover to cover so know how to do this on my car.  I’m sure many don’t.

michaels

noitsnotme said:

michaels said:

I have a recall on my nissan leaf: Nissan has identified a concern affecting the Vehicle Control Module (VCM) software logic following routine internal testing.  In specific and rare circumstances, after switching off cruise control and then within a certain timeframe changing the drive mode whilst quickly applying the throttle there is a possibility of temporary unintended acceleration.

So not out with possibility that there was a software error.

Plus there is software between the brake pedal and the braking power applied as lower levels of braking are intercepted and regen is applied, when the battery is 100% more brake travel is needed to get retardation so there is not simply a direct link from the brake pedal to the brakes anymore.

I think on the leaf there is a way to put the transmission into N whilst in motion but I never use it so would not know how to do it off the top of my head despite 9 years of ownership and 80k miles driven.

Agree the driver probably could have achieved a stop by stomping hard enough on the brake pedal (until the fluid boiled anyway) but if the car was determined to try to maintain 30mph that sounds pretty difficult, no idea if there is a mechanically operated handbrake on a ZS or simply an electronic switch that no doubt can not be engaged if the vehicle is in motion.  There is also probably like on the leaf a way to select neutral but the driver likely wouldn't know how to and it would also no doubt involve electronics which might not be active if there were some major ECU failure,  Thee is obviously no way to 'stall out' the engine and I suspect no way top switch off the car whilst in option (as this would be dangerous).

So not impossible with enough ECU fails for the only way to stop the vehicle being unassisted breaking vs a 173bhp motor.

Apparently you can apply the electronic parking brake while it’s moving.  According to another forum the manual says…

”Emergency Braking Function
If whilst driving the vehicle there is a footbrake failure, the vehicle can be decelerated by pulling up and holding EPB switch.”

Although how many owners read the manual and would know this.

I’m quite ocd with manuals and read the Tesla one (virtual) cover to cover so know how to do this on my car.  I’m sure many don’t.

Again though, that is an electronically controlled mechanism so depending on what the electronics thought thy were doing, could have been inoperative, unlike pulling on a handle connected by a wire to a brake drum.

noitsnotme

michaels said:

noitsnotme said:

michaels said:

I have a recall on my nissan leaf: Nissan has identified a concern affecting the Vehicle Control Module (VCM) software logic following routine internal testing.  In specific and rare circumstances, after switching off cruise control and then within a certain timeframe changing the drive mode whilst quickly applying the throttle there is a possibility of temporary unintended acceleration.

So not out with possibility that there was a software error.

Plus there is software between the brake pedal and the braking power applied as lower levels of braking are intercepted and regen is applied, when the battery is 100% more brake travel is needed to get retardation so there is not simply a direct link from the brake pedal to the brakes anymore.

I think on the leaf there is a way to put the transmission into N whilst in motion but I never use it so would not know how to do it off the top of my head despite 9 years of ownership and 80k miles driven.

Agree the driver probably could have achieved a stop by stomping hard enough on the brake pedal (until the fluid boiled anyway) but if the car was determined to try to maintain 30mph that sounds pretty difficult, no idea if there is a mechanically operated handbrake on a ZS or simply an electronic switch that no doubt can not be engaged if the vehicle is in motion.  There is also probably like on the leaf a way to select neutral but the driver likely wouldn't know how to and it would also no doubt involve electronics which might not be active if there were some major ECU failure,  Thee is obviously no way to 'stall out' the engine and I suspect no way top switch off the car whilst in option (as this would be dangerous).

So not impossible with enough ECU fails for the only way to stop the vehicle being unassisted breaking vs a 173bhp motor.

Apparently you can apply the electronic parking brake while it’s moving.  According to another forum the manual says…

”Emergency Braking Function
If whilst driving the vehicle there is a footbrake failure, the vehicle can be decelerated by pulling up and holding EPB switch.”

Although how many owners read the manual and would know this.

I’m quite ocd with manuals and read the Tesla one (virtual) cover to cover so know how to do this on my car.  I’m sure many don’t.

Again though, that is an electronically controlled mechanism so depending on what the electronics thought thy were doing, could have been inoperative, unlike pulling on a handle connected by a wire to a brake drum.

Reading the MG forum (although I realise they are somewhat biased and will want to protect their chosen car) it’s just another in a long list of things that would have all needed to have gone wrong simultaneously.  While there is the possibility of total system failure, there are other factors that appear to point towards it all being a set up.  No damage to the front of the car, the way his wife was able to attend and block off junction after junction before the police arrived.  It does seem a little far fetched.  I’m sure we’ll find out one way or another soon enough.

Netexporter

michaels said:

noitsnotme said:

michaels said:

I have a recall on my nissan leaf: Nissan has identified a concern affecting the Vehicle Control Module (VCM) software logic following routine internal testing.  In specific and rare circumstances, after switching off cruise control and then within a certain timeframe changing the drive mode whilst quickly applying the throttle there is a possibility of temporary unintended acceleration.

So not out with possibility that there was a software error.

Plus there is software between the brake pedal and the braking power applied as lower levels of braking are intercepted and regen is applied, when the battery is 100% more brake travel is needed to get retardation so there is not simply a direct link from the brake pedal to the brakes anymore.

I think on the leaf there is a way to put the transmission into N whilst in motion but I never use it so would not know how to do it off the top of my head despite 9 years of ownership and 80k miles driven.

Agree the driver probably could have achieved a stop by stomping hard enough on the brake pedal (until the fluid boiled anyway) but if the car was determined to try to maintain 30mph that sounds pretty difficult, no idea if there is a mechanically operated handbrake on a ZS or simply an electronic switch that no doubt can not be engaged if the vehicle is in motion.  There is also probably like on the leaf a way to select neutral but the driver likely wouldn't know how to and it would also no doubt involve electronics which might not be active if there were some major ECU failure,  Thee is obviously no way to 'stall out' the engine and I suspect no way top switch off the car whilst in option (as this would be dangerous).

So not impossible with enough ECU fails for the only way to stop the vehicle being unassisted breaking vs a 173bhp motor.

Apparently you can apply the electronic parking brake while it’s moving.  According to another forum the manual says…

”Emergency Braking Function
If whilst driving the vehicle there is a footbrake failure, the vehicle can be decelerated by pulling up and holding EPB switch.”

Although how many owners read the manual and would know this.

I’m quite ocd with manuals and read the Tesla one (virtual) cover to cover so know how to do this on my car.  I’m sure many don’t.

Again though, that is an electronically controlled mechanism so depending on what the electronics thought thy were doing, could have been inoperative, unlike pulling on a handle connected by a wire to a brake drum.

I've just had a look at the parking brake instructions for my MG5, which I'm pretty certain is similar to the ZS. It has a similar instruction to lift the EPB switch, as noted above, if the brake fails to engage when P is selected on the drive control. It also says the EPB fails-safe in the even of a power failure, so I think it should be able to be applied in any circumstance.

I'll await the recall on my car with interest!