The Age of Electric Vehicles

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Sciolus
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Re: The Age of Electric Vehicles

Post by Sciolus » Wed Jan 12, 2022 9:19 am

For an ICE, trip distance is also important, because you spend the first ten minutes heating half a tonne of metal up to 90 degrees.

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Re: The Age of Electric Vehicles

Post by IvanV » Wed Jan 12, 2022 9:35 am

Gfamily wrote:
Wed Jan 12, 2022 12:35 am
Bird on a Fire wrote:
Wed Jan 12, 2022 12:24 am
I often wonder what's the most efficient speed to drive at. If I bumble along at a solid 90km/h it maybe adds a few minutes to my commute compared with 120km/h, but it keeps the revs so much lower I assume I'm saving fuel.

Presumably you can also extend an EV's range by driving efficiently? I've even seen suggestions of lowering the speed limit to reduce CO2 emissions.
If a motorway has a 50mph limit because of roadworks, our average mph goes up to c50/52 mpg rather than the c46mpg we average when travelling at our usual 66/70mph.

ETA: air resistance goes as 4th power of speed (i think), so high speeds can make a big difference
The traditional number is that cars are most efficient at around 80-90 km/h. The engine itself has a sweet spot, and then you need to get into a gear which is as high as you can sweetly run. But you can't just put in ever higher gears and get even more efficient, because air resistance goes up.

It is one reason that you get surprisingly good fuel efficiency out of a system where petrol engine charges a battery, and the wheels are moved by electric motors. (What is marketed as a self-charging hybrid, trying to distract from the fact that it runs entirely on petrol). Despite the losses in charging the battery, you get a benefit from being able always to run the engine at it's efficient sweet spot, which, depending on kind of journeys you drive, can result in lower fuel consumption. (But why they don't go the small step further and let you plug them in is beyond me, given most journeys are short. Can it really add that much extra to the cost of the vehicle?)

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Re: The Age of Electric Vehicles

Post by lpm » Wed Jan 12, 2022 9:41 am

Sciolus wrote:
Wed Jan 12, 2022 9:19 am
For an ICE, trip distance is also important, because you spend the first ten minutes heating half a tonne of metal up to 90 degrees.
Same for an EV, because you spend the first few minutes heating half a tonne of batteries up to about 15 degrees.

At least, that's how the VW ID series work - poor winter efficiency if you just do short journeys.
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Re: The Age of Electric Vehicles

Post by shpalman » Wed Jan 12, 2022 9:49 am

bjn wrote:
Wed Jan 12, 2022 9:09 am
Average car usage in the UK seems to be roughly 10 miles/day. That will be some distribution with road warriors driving a million miles/day at one end and OAP's driving a mile once a month to the bingo hall down the road.

At 3.5 miles/kWh that translates to an average energy consumption of 3kWh/day, which is less than half an hour in a 7kW charger. Say you charge once a week, that's less than four hours on a week on a charger.

Driving across Europe on your summer hols is the corner case, Lidl/school runs are the vast majority of trips.
True, I've done that trip twice in the whole time I've owned the car. Before the Event I would fill up about once a month, but there was a phase when it was nearly twice a month because I was going to Milan a lot in the evenings. So 300-500 km a month, Milan is a 100 km round trip. At the end of October I went to (somewhere near) Turin, and I can get there (and use the car a bit there) and back (~350 km).

These days I have the battery connected to a trickle charger most of the time because of how little I'm using it.

But I'm still curious about whether I could have done my trip across Europe with an EV, based on range and where I could have stopped to charge. As it was, I managed to only fill up in Austria, where petrol is much cheaper.
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Re: The Age of Electric Vehicles

Post by Martin Y » Wed Jan 12, 2022 10:44 am

shpalman wrote:
Wed Jan 12, 2022 9:07 am
...
My ~20 year old sports car achieved about 6.6 l/100km (35.6 mpg(US), 42.8 mpg(UK), 0.066 mm2) on my trip to Slovakia and back (to Italy) including however much evaporated in the two weeks it was parked in Slovakia hardly going anywhere. Normally I get somewhere between 8 and 10 l/100km. Note that I don't have a fuel consumption gauge or anything, this is based on how many km I did and how many litres I filled up with, so also includes the angel's share.
It used to be that evaporation from petrol tanks emitted more hydrocarbons than came unburnt out of the exhaust. But evaporation controls have been getting increasingly elaborate for some decades. My older model has a one-way valve in the fuel cap to let air in as the tank empties and a vent pipe which goes via a canister of charcoal granules to absorb fumes, and that gets air drawn back through it while the car's cruising to scavenge fumes and feed them into the engine. Later ones like yours I think draw a small partial vacuum on the fuel tank and check it's maintained. The US model does anyway: it warns you if you failed to tighten the petrol cap.

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Re: The Age of Electric Vehicles

Post by shpalman » Wed Jan 12, 2022 10:55 am

Martin Y wrote:
Wed Jan 12, 2022 10:44 am
shpalman wrote:
Wed Jan 12, 2022 9:07 am
...
My ~20 year old sports car achieved about 6.6 l/100km (35.6 mpg(US), 42.8 mpg(UK), 0.066 mm2) on my trip to Slovakia and back (to Italy) including however much evaporated in the two weeks it was parked in Slovakia hardly going anywhere. Normally I get somewhere between 8 and 10 l/100km. Note that I don't have a fuel consumption gauge or anything, this is based on how many km I did and how many litres I filled up with, so also includes the angel's share.
It used to be that evaporation from petrol tanks emitted more hydrocarbons than came unburnt out of the exhaust. But evaporation controls have been getting increasingly elaborate for some decades. My older model has a one-way valve in the fuel cap to let air in as the tank empties and a vent pipe which goes via a canister of charcoal granules to absorb fumes, and that gets air drawn back through it while the car's cruising to scavenge fumes and feed them into the engine. Later ones like yours I think draw a small partial vacuum on the fuel tank and check it's maintained. The US model does anyway: it warns you if you failed to tighten the petrol cap.
I certainly notice the small partial vacuum when I take the cap off to fill the tank. The petrol cap clicks as you tighten it.
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Re: The Age of Electric Vehicles

Post by dyqik » Wed Jan 12, 2022 12:37 pm

lpm wrote:
Wed Jan 12, 2022 9:41 am
Sciolus wrote:
Wed Jan 12, 2022 9:19 am
For an ICE, trip distance is also important, because you spend the first ten minutes heating half a tonne of metal up to 90 degrees.
Same for an EV, because you spend the first few minutes heating half a tonne of batteries up to about 15 degrees.

At least, that's how the VW ID series work - poor winter efficiency if you just do short journeys.
That's going to be true for anything with lithium ion batteries. And drawing the power from cold batteries to provide that heat to the batteries at the same time as driving is inefficient.

It's also why I mentioned that as a possible use case for solar cells on a vehicle, with the thought of preheating vehicles on either solar or mains power.

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Re: The Age of Electric Vehicles

Post by dyqik » Wed Jan 12, 2022 12:40 pm

lpm wrote:
Wed Jan 12, 2022 8:59 am
Martin_B wrote:
Wed Jan 12, 2022 12:58 am
I find that driving around Perth on roads with 60-80 km/h speed limits I can usually get ~6 litres/100 km (sorry, that's the way my car reports it!).

But when doing long drives on roads with higher speed limits (between 100 km/h and 130 km/h) I could get down to 4.5 litres/100 km quite easily. I'm not sure lpm's idea:
lpm wrote:
Tue Jan 11, 2022 5:20 pm
A 58 kWh ID.3 has a real world range of 215 miles (less in winter, more in summer, less on motorways, more in cities).
is accurate, as on motorways you do drive faster and so have more drag, but you also tend to drive more consistently and so have fewer accelerations and decelerations. (Oz highways may be different to UK motorways, though!)
EVs have a different profile to ICE. They do best in slow city travel because they just regen any slowing. They enjoy a nice traffic jam on the motorway but can't defeat drag at 70 mph.
This isn't quite true - as mentioned above for the Prius. Regen isnt effective at braking a vehicle below ~7mph, so stop start traffic results in the traditional brakes being used.

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Re: The Age of Electric Vehicles

Post by nekomatic » Wed Jan 12, 2022 12:41 pm

IvanV wrote:
Wed Jan 12, 2022 9:35 am
It is one reason that you get surprisingly good fuel efficiency out of a system where petrol engine charges a battery, and the wheels are moved by electric motors. (What is marketed as a self-charging hybrid, trying to distract from the fact that it runs entirely on petrol). Despite the losses in charging the battery, you get a benefit from being able always to run the engine at it's efficient sweet spot, which, depending on kind of journeys you drive, can result in lower fuel consumption. (But why they don't go the small step further and let you plug them in is beyond me, given most journeys are short. Can it really add that much extra to the cost of the vehicle?)
I'm almost certain that most or all hybrid cars you can buy are parallel hybrids not series hybrids, in other words both the engine and the electric motor-generator drive the wheels through a mechanical transmission. Otherwise you'd need a bigger motor to deliver the full engine power and an equally big generator to convert the engine's power to electricity to run the big motor. I know that works for diesel-electric trains, but guess the numbers don't make sense for a car. Some hybrids (e.g. Toyotas) use a continuously variable transmission to keep the engine at an optimum speed, but others just have a more conventional automatic gearbox.

The battery in a non-plugin hybrid really isn't big enough to get the car very far (or very fast, given it's not sized for the full engine power) so no, I don't think it would make sense to add the cost of being able to plug it in. The issue with plugin hybrids is that once you make the battery big enough to have a usable electric range, the extra weight means that after you use up the electric range the car can end up using more fuel for subsequent driving than its non-hybrid equivalent.
Grumble wrote:
Wed Jan 12, 2022 6:57 am
As EVs generally have one gear unless there’s a sweet spot with the motor the most efficient speed will be as slow as possible, I think.
There'll be some baseline power consumption that starts to dominate at very slow speeds, but I would guess the optimum will be much slower than anyone would want to go.
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Re: The Age of Electric Vehicles

Post by dyqik » Wed Jan 12, 2022 12:44 pm

shpalman wrote:
Wed Jan 12, 2022 9:07 am
I think air resistance goes as the square of speed, so the energy used per unit time goes as the cube of speed, but of course you get there faster, so energy used per unit distance goes as the square of speed again.
This is only true while the drag coefficient remains constant. But as speed changes, there drag coefficient can reduce (or increase) substantially.

There was a conversation here/there a while back about party balloons. If you bat a balloon hard across a room, then it'll move fairly fast and then suddenly slow. This is because the drag coefficient suddenly increases as it slows, by a factor of ~5, as the airflow around it transitions from turbulent to laminar flow.

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Re: The Age of Electric Vehicles

Post by lpm » Wed Jan 12, 2022 12:52 pm

dyqik wrote:
Wed Jan 12, 2022 12:40 pm
This isn't quite true - as mentioned above for the Prius. Regen isnt effective at braking a vehicle below ~7mph, so stop start traffic results in the traditional brakes being used.
I don't believe that's the case for full EVs. They don't use the friction brakes at all, except in emergency stops or very hard braking. This is why there's a trend towards one pedal driving like for Nissan Leaves.
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Re: The Age of Electric Vehicles

Post by dyqik » Wed Jan 12, 2022 12:53 pm

nekomatic wrote:
Wed Jan 12, 2022 12:41 pm
IvanV wrote:
Wed Jan 12, 2022 9:35 am
It is one reason that you get surprisingly good fuel efficiency out of a system where petrol engine charges a battery, and the wheels are moved by electric motors. (What is marketed as a self-charging hybrid, trying to distract from the fact that it runs entirely on petrol). Despite the losses in charging the battery, you get a benefit from being able always to run the engine at it's efficient sweet spot, which, depending on kind of journeys you drive, can result in lower fuel consumption. (But why they don't go the small step further and let you plug them in is beyond me, given most journeys are short. Can it really add that much extra to the cost of the vehicle?)
I'm almost certain that most or all hybrid cars you can buy are parallel hybrids not series hybrids, in other words both the engine and the electric motor-generator drive the wheels through a mechanical transmission. Otherwise you'd need a bigger motor to deliver the full engine power and an equally big generator to convert the engine's power to electricity to run the big motor. I know that works for diesel-electric trains, but guess the numbers don't make sense for a car. Some hybrids (e.g. Toyotas) use a continuously variable transmission to keep the engine at an optimum speed, but others just have a more conventional automatic gearbox.

The battery in a non-plugin hybrid really isn't big enough to get the car very far (or very fast, given it's not sized for the full engine power) so no, I don't think it would make sense to add the cost of being able to plug it in. The issue with plugin hybrids is that once you make the battery big enough to have a usable electric range, the extra weight means that after you use up the electric range the car can end up using more fuel for subsequent driving than its non-hybrid equivalent.
The electric range of plugin hybrids seems to be fairly well chosen to cover completely day to day short urban journeys, and only needing the ICE for journeys long enough to be on a highway at constant high speed. That matches up pretty well to the efficiencies of each part of the system, as extra weight is less of an issue for efficiency in highway driving.

Range extended plugin EVs (i.e. EVs with an onboard generator) do exist - the Chevy Volt, for example.

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Re: The Age of Electric Vehicles

Post by dyqik » Wed Jan 12, 2022 1:00 pm

lpm wrote:
Wed Jan 12, 2022 12:52 pm
dyqik wrote:
Wed Jan 12, 2022 12:40 pm
This isn't quite true - as mentioned above for the Prius. Regen isnt effective at braking a vehicle below ~7mph, so stop start traffic results in the traditional brakes being used.
I don't believe that's the case for full EVs. They don't use the friction brakes at all, except in emergency stops or very hard braking. This is why there's a trend towards one pedal driving like for Nissan Leaves.
I'd expect it to be true at some level for holding the vehicle still on hills when stopped - a stationary motor only provides significant torque to resist movement if it's powered and dissipating energy, which is inefficient.

One pedal driving doesn't necessarily require regen only braking - the brake pedal in a Prius already controls regen and hydraulic brakes, and the hydraulic brakes can be activated electrically (the reason that you have to disconnect the 12V battery to do brake work on the Prius). Adding that control to one pedal driving is mostly a software change.

There's also a net inefficiency with not using the brakes at all - they rust, no longer work well in emergencies, and have to be replaced. Something that happens to our Prius, which is on its fourth set of rear rotors and third rear calipers at 100k miles.

This also provides you with an easy way to see if an EV uses it's brakes: shiny rotors are used regularly, and rusty rotors haven't been used for a week or more (weather dependent).

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Re: The Age of Electric Vehicles

Post by lpm » Wed Jan 12, 2022 1:31 pm

Yes, people seem to recommend that EV drivers should perform hard stops every now and again to stop the brakes from rusting up, or whatever they do. And the VW ID3 has old fashioned cheap brakes, not the modern fancy brakes, can't remember what they're called now, because they don't get used and are cheaper to service.
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Re: The Age of Electric Vehicles

Post by dyqik » Wed Jan 12, 2022 8:13 pm


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Re: The Age of Electric Vehicles

Post by monkey » Wed Jan 12, 2022 8:48 pm

dyqik wrote:
Wed Jan 12, 2022 8:13 pm
Custom exhausts for your EV:

https://www.millteksport.com/active-sou ... ta105.html
I hope someone hacks it and makes everyone's cars sound like crazy frog.

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Re: The Age of Electric Vehicles

Post by Bird on a Fire » Wed Jan 12, 2022 11:12 pm

crazy frog > crazy smog
You can shove your climate crisis up your arse!

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Re: The Age of Electric Vehicles

Post by Millennie Al » Thu Jan 13, 2022 1:52 am

Bird on a Fire wrote:
Wed Jan 12, 2022 12:24 am
I've even seen suggestions of lowering the speed limit to reduce CO2 emissions.
That was tried in the USA in 1973 - though the way it was expressed was as a measure to save fuel which is obviously exactly the same thing as reducing emissions. I haven't seen any evidence which says how much, if an, was saved.
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Re: The Age of Electric Vehicles

Post by Imrael » Thu Jan 13, 2022 11:32 am

Ivan: I'm almost certain that most or all hybrid cars you can buy are parallel hybrids not series hybrids
I think your right. The Vauxhall one (Ampex?) and the I3 Rex were series hyibrids, although the Rex (in initial version at least) only had about 2 teacups of petrol for some California incentive reason.

@Shpalman the Tesla route planner thinks you could do Bratislava to Milan with 3 charge stops totalling 1hr 15 mins in a M3 LR. (total jopurney time 11 hours) Admittedly this is close to best case in terms of charge network and car, but not too outrageous.

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Re: The Age of Electric Vehicles

Post by bjn » Thu Jan 13, 2022 3:17 pm

Imrael wrote:
Thu Jan 13, 2022 11:32 am

@Shpalman the Tesla route planner thinks you could do Bratislava to Milan with 3 charge stops totalling 1hr 15 mins in a M3 LR. (total jopurney time 11 hours) Admittedly this is close to best case in terms of charge network and car, but not too outrageous.
I usually need to pee and eat several times on such a journey.

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Re: The Age of Electric Vehicles

Post by shpalman » Thu Jan 13, 2022 4:21 pm

bjn wrote:
Thu Jan 13, 2022 3:17 pm
Imrael wrote:
Thu Jan 13, 2022 11:32 am

@Shpalman the Tesla route planner thinks you could do Bratislava to Milan with 3 charge stops totalling 1hr 15 mins in a M3 LR. (total jopurney time 11 hours) Admittedly this is close to best case in terms of charge network and car, but not too outrageous.
I usually need to pee and eat several times on such a journey.
From Como, I stopped for lunch in Bregenz, stopped overnight near Munich, and stopped for lunch the next day in St. Pölten but that was a waste of time because it was Sunday. I'll have to choose a more interesting lunch stop next time, maybe somewhere on the edge of Vienna (I actually ended up driving past the Schönbrunn on the way back because of an autobahn tunnel closure, and ate sandwiches at a rest stop).

But yeah since I was on my own and trying to actually not hate the drive I only did 3-4 hours in a stint. So if I'd have been in an EV and there would have been charging points along the way it would have been fine.

(Maybe there were charging points but I'm not really in the habit of looking out for them or noticing them.)
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Re: The Age of Electric Vehicles

Post by FlammableFlower » Thu Jan 13, 2022 4:43 pm

Last summer, my neighbours did Bristol-(somewhere in the middle of)Poland and back in their Tesla and apparently everything went very smoothly.

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Re: The Age of Electric Vehicles

Post by Aoui » Thu Jan 13, 2022 4:53 pm

(Maybe there were charging points but I'm not really in the habit of looking out for them or noticing them.)
[/quote]

We've found that it differs per country and you have to make sure you stop earlier than you otherwise might, in case the chargers aren't working, are full or for some reason just hate your car. None of our various apps for finding chargers is all that great. Mind you, so far the only place where it's been truly abysmal was France, but that was enough to raise our blood pressure for a few months. The Netherlands is hit or miss as to whether they put up any signs on the highway as to whether that stop has chargers. France was good about it, but they rarely worked (at least for us...French people didn't seem to have problems quite as often). We haven't been on the autobahn enough in Germany to say either way and didn't notice either way in Belgium either since we just drove through there to get to and from France.

As far as the rest stop thing goes, I have noticed that they tend to put the chargers quite far from the toities. So those of us with pea sized bladders or...let's say...women who are pregnant or...once a month when they aren't pregnant....and children can also have issues (and I presume a few men, but they tend to just whip out their willies and take a leak wherever if they don't feel like making the trek). I swear I nearly peed my pants a few times hiking to the bathrooms. Often you can't even stop near the building first and then drive on...no..they have to make you try to walk scissor-legged all the way to the toilet. I figure these places are all designed by men.... Luckily apps are starting to let you search for chargers that have public restrooms nearby. That used to also be an issue...

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Re: The Age of Electric Vehicles

Post by Grumble » Thu Jan 13, 2022 5:22 pm

1,000 mile journey in an ID4
https://youtu.be/Z3VNti14Kj0
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Re: The Age of Electric Vehicles

Post by Martin Y » Thu Jan 13, 2022 5:28 pm

Imrael wrote:
Thu Jan 13, 2022 11:32 am
... The Vauxhall one (Ampex?) and the I3 Rex were series hyibrids, although the Rex (in initial version at least) only had about 2 teacups of petrol for some California incentive reason.
The incentive, I gather, was to get a green sticker which let you drive in carpool lanes with only one person aboard.

The BMW i3 Rex wouldn't have qualified if it ran for more miles on its petrol range extender than it could on its battery. So the California model was nobbled in software so you couldn't use all the petrol in the tank.

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