Will Electric Vehicles Be Viable? When?

[Brake Horse Power]

This has been discussed in the last 40 posts or so, starting last Friday morning.
I buy the explanation of prolonged braking needs as a limiting factor.

Guess I missed a few posts

[Brake Horse Power]

This has been discussed in the last 40 posts or so, starting last Friday morning.
I buy the explanation of prolonged braking needs as a limiting factor.

I don't. What's the reason it should be different to ICEs? I've read nothing which explains the difference, if it really exist

You mentioned previously that an electric motor has a more suitable torque curve, which is of course a fact. But you miss 6 gears so a lot of torque. A Tesla motor maybe does 12000rpm at top speed? The first 1000rpm aren't great efficiency wise. Having to tow in that region, and than going to maximum motor torque has impact on the thermal stability.

Than you have the question, is this governing for the motorsizing (or cooling system) or other parts like gears etc. If so the next question is, as raised here, how many people actually need to tow a lot? And do you want to adjust design accordingly making it more expensive for the masses to please a few.

[Just_a_fan]

I'm not sure any EV is rated to tow, other than the Tesla Model X,

Audi e-tron, Jaguar i-Pace, Mercedes-Benz EQC, Nissan e-NV200, Tesla Mod. 3.

Soon to come: Audi e-tron Sportback, Audi Q4 e-tron, Ford Mustang Mach-E, Polestar 2, Volvo XC40 Recharge, Skoda Vision iV, VW ID.4

How many passenger cars do you see towing anything these days?

I'd expect that'd be next on the 'banned list' due to 'safety reg's' &/or subject to extra licensing...

In the UK, anyone who attained their licence after 1 Jan 1997 already has limits on what they can tow without taking a special test:
- drive a car or van up to 3,500kg maximum authorised mass (MAM) towing a trailer of up to 750kg MAM
- tow a trailer over 750kg MAM as long as the combined MAM of the trailer and towing vehicle is no more than 3,500kg

Admittedly, these aren't overly onerous restrictions, but those of us that got our licences before that date can drive a vehicle/trailer combination of up to 8250kg which is more than anyone could routinely do here anyway. My current vehicle can tow 3.5t and has a maximum mass of a little over 3t so I'm well below what I can legally do.

I actually don't have a problem with additional testing/licensing for towing, even if I had to undertake it. We get a number of rolled/jack knifed caravans and trailers on the roads each year, most of them doubtless caused by incorrect loading and driving technique.

[Just_a_fan]

I don't. What's the reason it should be different to ICEs? I've read nothing which explains the difference, if it really exist

ICEs can always use engine braking, BEVs can’t guarantee that regen, which is the equivalent, is available at all times. So BEVs need bigger brakes for prolonged braking.

This happens in F1. At many circuits the deployment strategy has to make sure there is available regen capacity for the big stops towards the end of the lap because the rear physical brakes aren’t sized to do that repeatedly.

But modern ICEV have almost zero engine braking for better fuel efficiency, some even less than what regen provide

How much fuel does engine braking use over normal idle? Why should the engine be using fuel when not being asked to provide power? In my vehicle, when one comes off the throttle, the instantaneous mpg display goes through the roof, and engine braking occurs.

[Just_a_fan]

Yes i know your Range Rover says 40 miles on battery

Mine doesn't. The only battery in it is the big 100Ah 12V starting battery in the engine bay.

The point about hybrids is that they allow a gradual change from pure ICE to pure EV. The batteries will get better, range in EV mode will increase, people find that they hardly use the ICE, if ever. Then they'll feel comfortable moving to the full EV platform.

People generally don't like big changes that are imposed on them in a sudden way. Saying "you lot should all drive EVs in order to save the "Lesser Spotted Throat Warbler of Outer Mongolia", will get a loud "Foxtrot Oscar" in reply. So you say, "here, this hybrid lets you keep the air near your children's schools and play grounds clean but still drive to Granny's house 200 miles away without worrying about getting there and back". "Ooh, that sounds good, we'll try that" followed by "ooh, we're finding that we hardly ever fill up with dino juice" and then "ooh, we can probably live with an EV after all".

You can't do a hand brake turn in a super tanker. People are like super tankers - changing direction needs planning and careful application of the controls over a period of time.

[Tommy Cookers]

... the Tesla 3 iirc having induction machines (making it go and regenerate-slow) it is spectacularly unsuited to towing
with an open loop system the 'controller' only works as certified if the EV characteristic matches that programmed

CORRECTION - the Tesla 3 has SWITCHED RELUCTANCE machine(s) making it go and regenerate-slow
says https://cleantechnica.com/2018/03/11/te ... -in-depth/
(and yes afaik it suggests limitations on regeneration close to zero speed)

[henry]

I think the Model 3 performance uses two different motors for AWD. Permanent magnet at the rear and induction at the front. I assume that a lot of the time the front motor is a passenger.

[Ferry]

How many passenger cars do you see towing anything these days?

A whole lot! I guess that is very different in different markets. Tow hitch on small cars like VW Golf or similar is very common here. Not many pick-up trucks though. One of the big selling points for Tesla 3 here is the possibility to tow. And EVs have more than 50% market share here now. https://cleantechnica.com/2020/02/05/no ... r-on-year/

[Andres125sx]

ICEs can always use engine braking, BEVs can’t guarantee that regen, which is the equivalent, is available at all times. So BEVs need bigger brakes for prolonged braking.

This happens in F1. At many circuits the deployment strategy has to make sure there is available regen capacity for the big stops towards the end of the lap because the rear physical brakes aren’t sized to do that repeatedly.

But modern ICEV have almost zero engine braking for better fuel efficiency, some even less than what regen provide

I’m not familiar with that, not much experience with modern cars. My last 2 cars, both autos, have downshifted on downhill, zero throttle, and provided engine braking. How does not doing this help fuel efficiency?

If the battery is full regen will be zero.

I´m not familiar with modern cars either, but the bmw of my father has so little engine braking it did surprise me first time I drove it

Think about flat terrain, if you release throttle and engine braking makes you loose speed, you´ll need to keep accelerating longer, while if there´s almost no engine braking you can release throttle much sooner, and let the car go with its inertia. Difference is noticeable and need some time to get used, imagine a 3km straight with a stop at the end, with engine braking you must accelerate for 2.5km and the final 500m you can release throttle and let the car loose some speed before braking, but without engine braking you can release throttle half straight and let the car go without throttle for a full km more than with engine braking.

Coincidence or not, that car has the lowest fuel consumption Ive seen for a normal car with normal size engine (140hp and 4,3l/100km), and my father enjoy driving, now at 80 he´s doesn´t drive too fast, but let´s say he´s far from the slowest at the roads

[Andres125sx]

ICEs can always use engine braking, BEVs can’t guarantee that regen, which is the equivalent, is available at all times. So BEVs need bigger brakes for prolonged braking.

This happens in F1. At many circuits the deployment strategy has to make sure there is available regen capacity for the big stops towards the end of the lap because the rear physical brakes aren’t sized to do that repeatedly.

But modern ICEV have almost zero engine braking for better fuel efficiency, some even less than what regen provide

How much fuel does engine braking use over normal idle? Why should the engine be using fuel when not being asked to provide power? In my vehicle, when one comes off the throttle, the instantaneous mpg display goes through the roof, and engine braking occurs.

As I´ve just explained, it´s not the fuel it takes when one comes off the throttle, but the time you need to keep your foot on the throttle, much longer with engine braking than without

Anyone who ride bikes know what I´m talking about, bikes provide tons of engine braking compared to any car, even the old ones, so riders need to keep the throttle open almost up to the corner, or you simply run out of speed. Bikes brakes can be almost ignored if you´re not riding fast, you just use it to completely stop it as you can´t use engine braking to 0 km/h, but that´s one of the reasons bikes use a lot more fuel (relative to its weight) compared to any car, throttle need to be open a much higher percentage

[Greg Locock]

"How much fuel does engine braking use over normal idle? Why should the engine be using fuel when not being asked to provide power?"

When engine braking in a modern car you don't use any fuel. For emissions reasons they often used to have a quick burn at 1800 rpm (ish) on the way down, but that's gone a long time ago.

[Just_a_fan]

Reading your two posts, I think you're confusing engine braking with drag. Modern cars are slippery so when you come off the throttle they don't slow down very quickly. Of course, a man on a bike is not slippery, he's quite a drag load so will help to slow the bike. The car has much more inertia, being much more massive, but also being more aerodynamic has similar drag. Hence the car tends to feel less effect off throttle than the bike. CdA comparison by looking at these two random google-found sources (if better sources can be pointed to, that would be great) :
http://elmoto.net/showthread.php?t=3400
https://en.wikipedia.org/wiki/Automobil ... oefficient
Obviously the rider's position makes a big difference e.g. crouched behind a fairing vs sat more upright in the breeze.

For engine braking when towing, I'm talking about using lower gears to help with speed control, not just coming off the throttle.

With EVs, one needs to stay on the "throttle" longer because as soon as you come off it, you start to get regen braking although I think you can often adjust this feature to give more/less braking when off throttle. Some EVs can be driven as a single pedal system other than for the last bit of stopping - much like your bike example, in effect. How good that is at holding back an additional load e.g. a big trailer, I don't know. Maybe it's now been worked out and that's why towing capability is being seen in the latest models.

[Andres125sx]

This has been discussed in the last 40 posts or so, starting last Friday morning.
I buy the explanation of prolonged braking needs as a limiting factor.

I don't. What's the reason it should be different to ICEs? I've read nothing which explains the difference, if it really exist

You mentioned previously that an electric motor has a more suitable torque curve, which is of course a fact. But you miss 6 gears so a lot of torque. A Tesla motor maybe does 12000rpm at top speed? The first 1000rpm aren't great efficiency wise. Having to tow in that region, and than going to maximum motor torque has impact on the thermal stability.

Than you have the question, is this governing for the motorsizing (or cooling system) or other parts like gears etc. If so the next question is, as raised here, how many people actually need to tow a lot? And do you want to adjust design accordingly making it more expensive for the masses to please a few.

This chart shows otherwise, efficiency at very low speed is quite good


Edit: this is different, shows poor performance under 10kmh but I'm not sure that explains a tow limitation

[Andres125sx]

Reading your two posts, I think you're confusing engine braking with drag. Modern cars are slippery so when you come off the throttle they don't slow down very quickly. Of course, a man on a bike is not slippery, he's quite a drag load so will help to slow the bike. The car has much more inertia, being much more massive, but also being more aerodynamic has similar drag. Hence the car tends to feel less effect off throttle than the bike. CdA comparison by looking at these two random google-found sources (if better sources can be pointed to, that would be great) :
http://elmoto.net/showthread.php?t=3400
https://en.wikipedia.org/wiki/Automobil ... oefficient
Obviously the rider's position makes a big difference e.g. crouched behind a fairing vs sat more upright in the breeze.

For engine braking when towing, I'm talking about using lower gears to help with speed control, not just coming off the throttle.

With EVs, one needs to stay on the "throttle" longer because as soon as you come off it, you start to get regen braking although I think you can often adjust this feature to give more/less braking when off throttle. Some EVs can be driven as a single pedal system other than for the last bit of stopping - much like your bike example, in effect. How good that is at holding back an additional load e.g. a big trailer, I don't know. Maybe it's now been worked out and that's why towing capability is being seen in the latest models.

I'm aware about drag, but drag difference is not that high between modern and old cars and engine braking difference is very noticeable even at 50kmh when drag is negligible

[Just_a_fan]

I'm aware about drag, but drag difference is not that high between modern and old cars and engine braking difference is very noticeable even at 50kmh when drag is negligible

Modern cars will have only 60% of the drag of old cars. That's a big difference.