The powers of EV's

[robinessex]

Undercover McNoName said:

robinessex said:

I guess jokes are lost on you then.

This is a fun one too, in the context of this thread. Keep dreaming in the nursery home, while yelling at passing EVs.

robinessex said:

I'm hoping that all EV's come with auto speed limit control, thus they'll all be confined to the inside lane of a motorway as they won't be able to overtake each other. The outside lane(s) will now be totally traffic free for us old gits in our ancient ICE horseless carriage to proceed at a leisurely 1 lepton or faster, all the speed cameras having been mothballed long ago.

With future 'big brother' controls and software on new cars coming, it may well be the future quite shortly. Now, where did that PH "Speed Matters" logo go?

[Puzzles]

Swmbo has never crashed my M3 P. They’re easy to drive so it isn’t an issue.

Only on PH could someone try to spin quick acceleration into a negative for EV.

[Terminator X]

GT9 said:

robinessex said:

I guess TC kicks in, but as pointed out a few postings ago, an EV can get out of control.

I don't think you've absorbed what I posted earlier.

It's got nothing to do with traction control.

It's inherent in the design of the drivetrain.

Here is the power curve for one of the most notorious 1000 bhp EVs.

Full power in NEVER available below 60 mph.

Damn, that P85 must have been so slow.

TX.

[robinessex]

Puzzles said:

Swmbo has never crashed my M3 P. They’re easy to drive so it isn’t an issue.

Only on PH could someone try to spin quick acceleration into a negative for EV.

I never said it was a negative, but 1g acceleration on the road? I've experienced that, and it is bloody dramatic. If you did that and wasn't prepared for it, you'd be in trouble before you knew what happened. I do indeed hold the view that a powerful car, well-driven, can actually be a safer vehicle.

[GT9]

robinessex said:

I'm guessing that's what I enquired about, the motor control system limits current and volts. An electric motor will draw much more current when stalled than when running. This is because when running, it is also acting as a generator, creating an EMF which opposes the applied EMF and reduces the overall current. A DC compound motor can run in series or shunt configuration, a bit like underground trains do. IN a DC shunt motor, torque is proportional to armature current. For a series-wound DC motor, torque increases as the square of the armature current.

EV traction motors are controlled by power electronics, aka, variable frequency drive.

The drive draws DC current from the battery, inverts it using high-frequency switched transistors to produce synchronous (or asynchronous) AC excitation of the motor stator windings.

The back-emf of the rotating magnetic field on the rotor can be produced in several way, either using induction, permanent magnets or a wound field rotor with brushes. There are several configurations in use.

The drive is controlling the current, and thus the torque of the motor, there is no inrush current or stall scenario to worry about.

The motor torque output is controlled at a quasi-fixed value from zero speed up to the constant power speed.

The power output therefore rises linearly from zero speed to the constant power speed.

The purpose of this is to match what is required for constant acceleration of a fixed mass object, i.e. a linear increase in power from zero speed.

This results in a fixed torque at the driven wheels that provides a constant accelerative force, as you alluded to earlier.

In the Tesla Plaid the constant power speed is geared to be at around 60 mph.

Above that, the torque decays, leaving a quasi-fixed power output.

[robinessex]

GT9 said:

robinessex said:

I'm guessing that's what I enquired about, the motor control system limits current and volts. An electric motor will draw much more current when stalled than when running. This is because when running, it is also acting as a generator, creating an EMF which opposes the applied EMF and reduces the overall current. A DC compound motor can run in series or shunt configuration, a bit like underground trains do. IN a DC shunt motor, torque is proportional to armature current. For a series-wound DC motor, torque increases as the square of the armature current.

EV traction motors are controlled by power electronics, aka, variable frequency drive.

The drive draws DC current from the battery, inverts it using high-frequency switched transistors to produce synchronous (or asynchronous) AC excitation of the motor stator windings.

The back-emf of the rotating magnetic field on the rotor can be produced in several way, either using induction, permanent magnets or a wound field rotor with brushes. There are several configurations in use.

The drive is controlling the current, and thus the torque of the motor, there is no inrush current or stall scenario to worry about.

The motor torque output is controlled at a quasi-fixed value from zero speed up to the constant power speed.

The power output therefore rises linearly from zero speed to the constant power speed.

The purpose of this is to match what is required for constant acceleration of a fixed mass object, i.e. a linear increase in power from zero speed.

This results in a fixed torque at the driven wheels that provides a constant accelerative force, as you alluded to earlier.

In the Tesla Plaid the constant power speed is geared to be at around 60 mph.

Above that, the torque decays, leaving a quasi-fixed power output.

Appreciate that, I'm afraid my memory from college on electrical stuff is a bit out of date and limited.

[Muzzer79]

robinessex said:

Puzzles said:

Swmbo has never crashed my M3 P. They’re easy to drive so it isn’t an issue.

Only on PH could someone try to spin quick acceleration into a negative for EV.

1g acceleration on the road? I've experienced that, and it is bloody dramatic. If you did that and wasn't prepared for it, you'd be in trouble before you knew what happened.

But why do you think people will be unprepared for it?

It's not like people are just getting in a random Tesla on the street that they know nothing about and setting off.

People buy cars. They take note of the specification, which is also explained to them by the vendor. If you go to the trouble of speccing an EV with 1000bhp, it won't be a surprise that it's very, very fast.

People will consequently brief whoever else drives it that it's very, very fast.

This is no different to someone who buys a BMW M5, for example. They know it's a fast car - they chose it accordingly. They will also tell other people that it's fast and requires care.

[WestyCarl]

robinessex said:

I never said it was a negative, but 1g acceleration on the road? I've experienced that, and it is bloody dramatic. If you did that and wasn't prepared for it, you'd be in trouble before you knew what happened. I do indeed hold the view that a powerful car, well-driven, can actually be a safer vehicle.

The accelerator isn't just on-off though.

My daugher has driven my Model 3 and it was no problem (her daily is a 107 that car barely do 60mph)

[robinessex]

Muzzer79 said:

robinessex said:

Puzzles said:

Swmbo has never crashed my M3 P. They’re easy to drive so it isn’t an issue.

Only on PH could someone try to spin quick acceleration into a negative for EV.

1g acceleration on the road? I've experienced that, and it is bloody dramatic. If you did that and wasn't prepared for it, you'd be in trouble before you knew what happened.

But why do you think people will be unprepared for it?

It's not like people are just getting in a random Tesla on the street that they know nothing about and setting off.

People buy cars. They take note of the specification, which is also explained to them by the vendor. If you go to the trouble of speccing an EV with 1000bhp, it won't be a surprise that it's very, very fast.

People will consequently brief whoever else drives it that it's very, very fast.

This is no different to someone who buys a BMW M5, for example. They know it's a fast car - they chose it accordingly. They will also tell other people that it's fast and requires care.

I quite agree that the buyers of these cars will be au fait with their capabilities. IF I was to buy one, I'd immediately look for some deserted place I could explore what it does at least once. It's the scenario of someone, usually family, who borrows it, and despite being told it's powerful and to be careful, doesn't listen or appreciate what its potential is.

[GT6k]

This is PH, it's very brave of the OP to suggest that there should be controls on how powerful a car we can own. I dare you to cross post this to the TVR section.

[raspy]

robinessex said:

I never said it was a negative, but 1g acceleration on the road? I've experienced that, and it is bloody dramatic. If you did that and wasn't prepared for it, you'd be in trouble before you knew what happened. I do indeed hold the view that a powerful car, well-driven, can actually be a safer vehicle.

Tell me OP, out of all the EVs that will be sold in this country, how many will be 1000 bhp Teslas? 5,000? 50,000? Even more? Will there be thousands around the nation all careering out of control by Sharons taking the kids to school? Is this "worry" in your mind justified? No.

[dvs_dave]

This is a truly bizarre “concern” from the OP and just seems like thinly veiled anti-EV twaddle.

It’s literary no different an “issue” (i.e. it isn’t one) than modern ICE cars compared to the pedestrian performance from vehicles of yore. People aren’t involuntarily crashing modern cars any more than old cars were. If fact cars are crashed way less than these days, despite them also being much much faster and immediate in their response, just like some EV’s are today compared to some modern ICE vehicles.

[SDK]

So a rich person buying a powerful ICE supercar is fine and will not crash it.
But a rich person buying an EV will crash it



Also, this happens

[Muzzer79]

robinessex said:

It's the scenario of someone, usually family, who borrows it, and despite being told it's powerful and to be careful, doesn't listen or appreciate what its potential is.

But that could happen with any fast car?

A BMW M5 has over 600bhp and (switchable) RWD. To the non-car aficionado, it just looks like a BMW.

I don't get why you think this is just an EV-specific problem.

[GT9]

SDK said:

So a rich person buying a powerful ICE supercar is fine and will not crash it.
But a rich person buying an EV will crash it

The desperation to find flaws in the 'EVil masterplan' is getting a bit tragic now.

This is the second thread this year started by someone claiming electric acceleration is very dangerous.

Sorry Rob

[robinessex]

GT9 said:

SDK said:

So a rich person buying a powerful ICE supercar is fine and will not crash it.
But a rich person buying an EV will crash it

The desperation to find flaws in the 'EVil masterplan' is getting a bit tragic now.

This is the second thread this year started by someone claiming electric acceleration is very dangerous.

Sorry Rob

As I've said, I've enjoyed 1g acceleration, if you're prepared, it's ok, but if it hits you when you're not, big oops!I Don't know the power it had, but an Ultima with a 7ltr tuned V8 up its arse gets pretty near to that. That's what I was told.

[smn159]

robinessex said:

GT9 said:

SDK said:

So a rich person buying a powerful ICE supercar is fine and will not crash it.
But a rich person buying an EV will crash it

The desperation to find flaws in the 'EVil masterplan' is getting a bit tragic now.

This is the second thread this year started by someone claiming electric acceleration is very dangerous.

Sorry Rob

As I've said, I've enjoyed 1g acceleration, if you're prepared, it's ok, but if it hits you when you're not, big oops!I Don't know the power it had, but an Ultima with a 7ltr tuned V8 up its arse gets pretty near to that. That's what I was told.

You think that road cars should be limited in some way?

What power level is acceptable to you?

[robinessex]

smn159 said:

robinessex said:

GT9 said:

SDK said:

So a rich person buying a powerful ICE supercar is fine and will not crash it.
But a rich person buying an EV will crash it

The desperation to find flaws in the 'EVil masterplan' is getting a bit tragic now.

This is the second thread this year started by someone claiming electric acceleration is very dangerous.

Sorry Rob

As I've said, I've enjoyed 1g acceleration, if you're prepared, it's ok, but if it hits you when you're not, big oops!I Don't know the power it had, but an Ultima with a 7ltr tuned V8 up its arse gets pretty near to that. That's what I was told.

You think that road cars should be limited in some way?

What power level is acceptable to you?

Assuming we're talking about cars for the average punter, who just wants point-to-point mobility, guess the norm before EVs came along was between 100-200bhp. Didn't hear any complaints about that. Cars of a sporting nature, it's always been an HP race, so carry on guys.

[Puzzles]

The average EV probably wont be that much quicker than similar ICE cars, the very quick ones are still expensive, similar to ICE cars.

[SpeckledJim]

robinessex said:

smn159 said:

robinessex said:

GT9 said:

SDK said:

So a rich person buying a powerful ICE supercar is fine and will not crash it.
But a rich person buying an EV will crash it

The desperation to find flaws in the 'EVil masterplan' is getting a bit tragic now.

This is the second thread this year started by someone claiming electric acceleration is very dangerous.

Sorry Rob

As I've said, I've enjoyed 1g acceleration, if you're prepared, it's ok, but if it hits you when you're not, big oops!I Don't know the power it had, but an Ultima with a 7ltr tuned V8 up its arse gets pretty near to that. That's what I was told.

You think that road cars should be limited in some way?

What power level is acceptable to you?

Assuming we're talking about cars for the average punter, who just wants point-to-point mobility, guess the norm before EVs came along was between 100-200bhp. Didn't hear any complaints about that. Cars of a sporting nature, it's always been an HP race, so carry on guys.

Is an M5 a ‘car of a sporting nature’?

How about an X5M?