EVs Guilt free lead foot? [Genuine technical question]
Discussion
5s Alive said:
Kawasicki said:
GT9 said:
Kawasicki said:
More accessible torque, more of the time, means more tyre slip and more tyre wear. Even if you have a perfectly smooth torque delivery, if you put more force through a contact patch you will wear the tyre faster.
Well, here's a question relating to a 0-60 run.Car A supplies a constant 3000 Nm of low oscillation torque to the rear wheels, but the car weighs 20% more.
Car B supplies a variable and high oscillation torque, peaking at over 5000 Nm to the front wheels, with a torque discontinuity at 35 mph to change gears.
The area under the torque curve for car B is slightly higher due to the high peak wheel torque.
The area under the torque curve of what is actually converted to acceleration force is likely to be higher for car A because there is no traction loss.
Car A carries a 'nameplate' peak torque value of 310 Nm at the motor.
Car B carries a 'nameplate' peak torque value of 350 Nm at the engine.
Neither nameplate value accounts for gearing between the motor or engine and the wheels.
Both reach 60 mph within approximately the same time.
Both are mainstream VAG cars.
Which one suffered higher tyre wear?
To assist, the wheel torque vs speed graphic below is a simplification of the actual torque at the driven wheels, as well as the sort of oscillations around nominal torque due to the nature of the prime mover providing the torque.
georgeyboy12345 said:
Lots of detailed technical posts in this thread, but all I know with my PHEV is if I’m running in EV mode and I boot it up to cruising speed at 100% power, rather than just gently accelerating up to cruising speed at 20-30% power, then the battery drains much more quickly!
Whilst that's true, what you need to bear in mind is that there is an energy balance situation going on in the background that doesn't mean you've wasted all that energy.What you've done is to take battery energy and convert it to kinetic energy.
The amount of kinetic energy the car carries at any given speed is the same regardless of how fast you got there.
Accelerating twice as fast requires twice as much power at any given speed, but it also halves the time to get to the final speed, so the total energy transfer is identical, i.e. energy is power multiplied by time.
If you use that energy to coast or it is mostly recovered by regen, then the battery has been used as a means of lending energy to the engine, or reducing the amount of fuel (i.e. energy) that the engine consumes.
Basically it comes out in the wash, and the only real difference is the heat that was lost in the process, which comes back to instantaneous efficiency during the acceleration run.
Yes, you will have produced more waste heat by booting it and the battery will definitely drain faster, but you've also put yourself further down the road, requiring less fuel from the engine to complete the whole journey.
What I'm trying to say is that unless you are able to quantify the exact amount of energy consumed in terms of fuel and electricity for two whole journeys where the only difference was booting it down the slip road, looking at the SOC of the battery isn't telling you the whole story.
5s Alive said:
Straight line run to 60. Constant vs variable torque minus weight difference. Potentially close, no?
Don't ignore the wheel slip that the FWD car will most likely encounter.The 'fuzziness' of the blue curve is a simplification to show the effect of fewer pulses per wheel revolution, resulting in a higher oscillation around nominal, so its not just the nominal value of torque but the inter-pulse variation that can cause more wear at the tread block as they deflect, grip and slip.
More pulses per rev and less boost would help, but fitting a normally aspirated V12 to a Golf GTi is not the work of a moment.
The Golf is also FWD, so you could say I'm biasing the outcome by comparing that to the RWD EV, a Cupra Born.
Be that as it may, the EV powertrain offers the RWD configuration.
A Golf R obviously deals with that as well, but it's not really a straight comparison of acceleration times anymore.
The purpose of the question was to highlight that determining tyre wear by a simple comparison of kerb mass and nameplate torque doesn't tell you everything.
In fact it doesn't tell you that much at all.
It doesn't account for gearing, gearchanges, the type of transmission/clutch/etc., the number and location of driven wheels, the number of cylinders and degree of boost, if any.
Wheel diameter also comes into it and I've assumed they are wearing the same outer diameter tyres for the purpose of comparison.
Obviously driving style also comes into it.
You might be right that there's nothing in it, but if the Golf is producing a larger area under its wheel torque curve, yet it weighs less and doesn't accelerate any quicker, you have to ask where all that energy went?
Did the torque sink downwards as the driven wheels lost traction, by virtue of traction control, or was some torque used to strip the tyres of rubber?
The specific answer for this specific comparison isn't that important.
What I believe is important is to recognise that there are many factors at play and simply fixating on either 'weight' or headline torque numbers isn't that useful.
High vs low oscillation vs a break in torque for the gear change. I don't know how significant the difference in oscillation is, or indeed how much this would contribute to wear. In reality this is probably impossible to physically measure and leaves me more uncertain as to whether the difference is insignificant or not. GT9 will no doubt update long after I've tied myself in knots.
And he beats me to it.
And he beats me to it.
5s Alive said:
TheDeuce said:
Erm... no.
Straight line run to 60. Constant vs variable torque minus weight difference. Potentially close, no?And it's something we've all witnessed I'm sure. Someone rags a reasonably powered ICE car, there's a scuffle from the tyres as it takes off and another chirp when they slam it into second. Those sounds are tyre wear made audible.
Tbh in GT9's chosen two car example, it probably makes next to no difference. Neither car has the torque to overwhelm their tyres grip, which is where the big damage is done. I also doubt the weight of the EV makes any difference in terms of a sprint either, because it's another factor that actually acts to reduce a tyre breaking traction enough to spin and scrub the rubber, along with the EV's innately higher level of torque control.
BUT.. for general motoring there is perhaps a win for the lighter ICE car. There's some evidence that EV weight, unsurprisingly, does in general wear tyres a little faster. As does the power during a tyres life, simply because the EV driver is more likely to accelerate hard more often!
TheDeuce said:
The peak torque is far higher (at the wheels) for the ICE in the example given, the higher the wheel torque, the higher the chance of over-rotating the wheels and scrubbing occurring. Whether it does or not depends on various factors - but naturally, the higher the torque and the more erratically it's applied (gear changes) the more likely you are to scrub the tyres a little.
And it's something we've all witnessed I'm sure. Someone rags a reasonably powered ICE car, there's a scuffle from the tyres as it takes off and another chirp when they slam it into second. Those sounds are tyre wear made audible.
Tbh in GT9's chosen two car example, it probably makes next to no difference. Neither car has the torque to overwhelm their tyres grip, which is where the big damage is done. I also doubt the weight of the EV makes any difference in terms of a sprint either, because it's another factor that actually acts to reduce a tyre breaking traction enough to spin and scrub the rubber, along with the EV's innately higher level of torque control.
BUT.. for general motoring there is perhaps a win for the lighter ICE car. There's some evidence that EV weight, unsurprisingly, does in general wear tyres a little faster. As does the power during a tyres life, simply because the EV driver is more likely to accelerate hard more often!
You should meet my neighbour. Moved from a Honda CRV to a Niro EV and is chewing through his tyres at a remarkable rate. He's convinced that it's because 'EVs eat tyres' and in a way he's right.And it's something we've all witnessed I'm sure. Someone rags a reasonably powered ICE car, there's a scuffle from the tyres as it takes off and another chirp when they slam it into second. Those sounds are tyre wear made audible.
Tbh in GT9's chosen two car example, it probably makes next to no difference. Neither car has the torque to overwhelm their tyres grip, which is where the big damage is done. I also doubt the weight of the EV makes any difference in terms of a sprint either, because it's another factor that actually acts to reduce a tyre breaking traction enough to spin and scrub the rubber, along with the EV's innately higher level of torque control.
BUT.. for general motoring there is perhaps a win for the lighter ICE car. There's some evidence that EV weight, unsurprisingly, does in general wear tyres a little faster. As does the power during a tyres life, simply because the EV driver is more likely to accelerate hard more often!
I've been in the car with him, hard acceleration out of junctions, regen at max and lifting off at the last second into downhill corners (and everywhere else) doesn't make for smooth progress. He didn't drive this way in the CRV.
5s Alive said:
You should meet my neighbour. Moved from a Honda CRV to a Niro EV and is chewing through his tyres at a remarkable rate. He's convinced that it's because 'EVs eat tyres' and in a way he's right.
I've been in the car with him, hard acceleration out of junctions, regen at max and lifting off at the last second into downhill corners (and everywhere else) doesn't make for smooth progress. He didn't drive this way in the CRV.
Indeed... Tyre wear aside, playing with the fast pedal is pretty much free, that's bloody liberating after a life driving ICE and the instant wallet hit if you get carried away.I've been in the car with him, hard acceleration out of junctions, regen at max and lifting off at the last second into downhill corners (and everywhere else) doesn't make for smooth progress. He didn't drive this way in the CRV.
TheDeuce said:
5s Alive said:
TheDeuce said:
Erm... no.
Straight line run to 60. Constant vs variable torque minus weight difference. Potentially close, no?And it's something we've all witnessed I'm sure. Someone rags a reasonably powered ICE car, there's a scuffle from the tyres as it takes off and another chirp when they slam it into second. Those sounds are tyre wear made audible.
Tbh in GT9's chosen two car example, it probably makes next to no difference. Neither car has the torque to overwhelm their tyres grip, which is where the big damage is done. I also doubt the weight of the EV makes any difference in terms of a sprint either, because it's another factor that actually acts to reduce a tyre breaking traction enough to spin and scrub the rubber, along with the EV's innately higher level of torque control.
BUT.. for general motoring there is perhaps a win for the lighter ICE car. There's some evidence that EV weight, unsurprisingly, does in general wear tyres a little faster. As does the power during a tyres life, simply because the EV driver is more likely to accelerate hard more often!
ChocolateFrog said:
Kawasicki said:
More accessible torque, more of the time, means more tyre slip and more tyre wear. Even if you have a perfectly smooth torque delivery, if you put more force through a contact patch you will wear the tyre faster.
I don't think that's true.5s Alive said:
You should meet my neighbour. Moved from a Honda CRV to a Niro EV and is chewing through his tyres at a remarkable rate. He's convinced that it's because 'EVs eat tyres' and in a way he's right.
I've been in the car with him, hard acceleration out of junctions, regen at max and lifting off at the last second into downhill corners (and everywhere else) doesn't make for smooth progress. He didn't drive this way in the CRV.
Why do you think he changed his driving style?I've been in the car with him, hard acceleration out of junctions, regen at max and lifting off at the last second into downhill corners (and everywhere else) doesn't make for smooth progress. He didn't drive this way in the CRV.
It reminds me of an Audi dealer I spoke to back in the 90‘s. He told me that normal customers were amazed how rapidly their Audi 80 Tdi‘s were getting through front tyres compared to the normally aspirated cars they owned previously.
Kawasicki said:
Why do you think he changed his driving style?
It reminds me of an Audi dealer I spoke to back in the 90‘s. He told me that normal customers were amazed how rapidly their Audi 80 Tdi‘s were getting through front tyres compared to the normally aspirated cars they owned previously.
He was never the smoothest driver before but the instantly accessible torque seems to have transformed his approach. "I never expected it to be so quick". He doesn't actually cover distance particularly quickly A to B but enjoys having regen at max so that he rarely has to brake. I'd say that this has had the main impact on his driving as he doesn't seem to be able to modulate very well. It reminds me of an Audi dealer I spoke to back in the 90‘s. He told me that normal customers were amazed how rapidly their Audi 80 Tdi‘s were getting through front tyres compared to the normally aspirated cars they owned previously.
Kawasicki said:
TheDeuce said:
5s Alive said:
TheDeuce said:
Erm... no.
Straight line run to 60. Constant vs variable torque minus weight difference. Potentially close, no?And it's something we've all witnessed I'm sure. Someone rags a reasonably powered ICE car, there's a scuffle from the tyres as it takes off and another chirp when they slam it into second. Those sounds are tyre wear made audible.
Tbh in GT9's chosen two car example, it probably makes next to no difference. Neither car has the torque to overwhelm their tyres grip, which is where the big damage is done. I also doubt the weight of the EV makes any difference in terms of a sprint either, because it's another factor that actually acts to reduce a tyre breaking traction enough to spin and scrub the rubber, along with the EV's innately higher level of torque control.
BUT.. for general motoring there is perhaps a win for the lighter ICE car. There's some evidence that EV weight, unsurprisingly, does in general wear tyres a little faster. As does the power during a tyres life, simply because the EV driver is more likely to accelerate hard more often!
But the greater the level of slip, the greater the scrubbing action.
There is an F1 motor racing saying "Old granny" used to describe the best way to get of the start line. Simply translated in an EV the motor can be controlled far better and enable optimal traction (taming power/torque). ICE engines are far less controllable and it's more the Wild West when it comes to getting the power down. A well optimised control system, tyre/tyre pressure and road surface stickiness are what are required to do quick 0-60s
TheDeuce said:
Of course, that's why tyres wear down on an old ladies honda jazz too..
Exactly that. Which is why lots of cornering (such as driving in town) can cause tyres to wear rapidly. Whereas long constant speed journeys in mostly straight lines such as motorway driving puts very little cornering or accelerating forces through the tyres, so very little slip. Our old 2 tonne (diesel) SUV used to get 60k miles out of a set of tyres, and a large part of that was because it spent a lot of those miles on motorways.
ashenfie said:
There is an F1 motor racing saying "Old granny" used to describe the best way to get of the start line. Simply translated in an EV the motor can be controlled far better and enable optimal traction (taming power/torque). ICE engines are far less controllable and it's more the Wild West when it comes to getting the power down. A well optimised control system, tyre/tyre pressure and road surface stickiness are what are required to do quick 0-60s
Quick 0-60s mostly need a huge force to be generated at the contact patch.5s Alive said:
Kawasicki said:
Why do you think he changed his driving style?
It reminds me of an Audi dealer I spoke to back in the 90‘s. He told me that normal customers were amazed how rapidly their Audi 80 Tdi‘s were getting through front tyres compared to the normally aspirated cars they owned previously.
He was never the smoothest driver before but the instantly accessible torque seems to have transformed his approach. "I never expected it to be so quick". He doesn't actually cover distance particularly quickly A to B but enjoys having regen at max so that he rarely has to brake. I'd say that this has had the main impact on his driving as he doesn't seem to be able to modulate very well. It reminds me of an Audi dealer I spoke to back in the 90‘s. He told me that normal customers were amazed how rapidly their Audi 80 Tdi‘s were getting through front tyres compared to the normally aspirated cars they owned previously.
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