EV-based road transportation is not viable

[tggzzz]

Water/urine/etc ingress and dirt ingress into the connectors and charging controller electronics?

That's why I said capacitive at first, you just need to roughly mate two surfaces. A little bit of dust and even water is not a problem, brush away the worst of it, use say a magnetic clamp to attach your cable. Magsafe for cars.

I missed that, and while I have heard of transformer coupling, I have never heard of capacitive coupling in the context of power transfer.

What capacity capacitor do you calculate would be necessary.

Have a chat to the people with experience of telecom footway boxes. They have plenty of experiences of low energy infrastructure. Charging infrastructure can never be low energy

But then what use is their experience?

They know what conditions are likely to exist. Their solutions will be for energy constrained systems (e.g. 48V current limited so as not to cause electric shock), but different solutions would be required for chargers.

For higher voltages you could try to have the plug suck vacuum to get a good seal, remaining water inside the socket can be flashed off. You can use a detector electrode just outside the seal as a fail safe so people walking bear foot past a slightly leaky plug don't get tingling feet.

Too many dangerous failure modes, in both everyday weather and extreme weather.

Besides, it isn't just the plug/socket, it is everything else in a charger.

[TimFox]

It's easy to calculate the capacitance of a proposed fixture, given the actual dimensions including plate area, material thickness, air gap, and dielectric properties of the material.
Note that the capacitance is inversely proportional to the spacing.
After that calculation, one can calculate the actual AC voltage required to drive this capacitor at a practical frequency (probably higher than 50/60 Hz) and obtain useful power levels at the vehicle load.
This is an engineering forum:  to advocate this method, one should include some quantitative estimates.

[tggzzz]

Water/urine/etc ingress and dirt ingress into the connectors and charging controller electronics?

That's why I said capacitive at first, you just need to roughly mate two surfaces. A little bit of dust and even water is not a problem, brush away the worst of it, use say a magnetic clamp to attach your cable. Magsafe for cars.

So your solution is to wipe a capacitor clean every evening (even in rain / snow) to charge your car for the next day after a days of hard work and wanting to have dinner? When I get home, I'm done with the car. Many times I don't even lock the car. I just want to go inside, have dinner and enjoy my evening.

But put some numbers to your capacitive charging idea and you'll see that it ends up needing extremely high voltages (likely in the hundreds of kV) to transfer a decent amount of power over a distance (say like 20cm).

Oh, it is worse than that

Get back, park, unravel the cable, find the charger doesn't work (physically broken, sensor failure, can't communicate the cost to your bank etc[1]).
Unplug, rewind cable, can't find any space in the road since everybody else returned earlier.
Drive around, finally spot a space, only to discover the space is empty because that charger is broken too.
Rinse and repeat...

Consider a much simpler problem: a machine to dispense car parking tickets for parking spaces on the road. Characteristics: above ground, one every 100m or so, low power. Given the proportion of those simple machines that are out of order when you try to buy a ticket, the reliability of roadside chargers is likely to be, um, less than acceptable.

[1] immediately after finishing this post, I blundered acr oss https://www.which.co.uk/news/article/energy-supplier-not-getting-readings-from-your-smart-meter-youre-not-alone-aVihU5a6LLKI
Those are in a comparitively benign indoor environment.

[Marco]

Besides, it isn't just the plug/socket, it is everything else in a charger.

Glue it to the heatsink and pot it. Except for the mains to electronics connection, but no doubt there are good standards and solutions for under ground mains connections already.

A ticket dispenser has UI and mechanical components. A minimal charger will just have a status LED and the connector exposed to humans (far more destructive than water).

This is an engineering forum:  to advocate this method, one should include some quantitative estimates.

Capacitive charging at KW level has been done, but with large plates. If you can get away with a small mating surfaces depends on the structural properties of high permittivity ceramics.

[rstofer]

Consider a much simpler problem: a machine to dispense car parking tickets for parking spaces on the road. Characteristics: above ground, one every 100m or so, low power. Given the proportion of those simple machines that are out of order when you try to buy a ticket, the reliability of roadside chargers is likely to be, um, less than acceptable.

Follow the money!  In the case of the ticket dispenser, the money goes to the City and repair is controlled by City employees.  They clearly don't give a damn at any level.

Hopefully, charging points will be owned by private enterprise and they have a profit motive for keeping them ALL working.  After all, there is no return on their capital investment if they can't sell kWh.

The .gov should clear the roadblocks but the work/return should all be private enterprise.

We'll get into the discussion of 'red-lining' (crossing out entire neighborhoods) later but that's one of those incentive deals where .gov can actually make a contribution to grease the skids.

In a lot of ways, charging points could be a public utility.  I wouldn't want to see it go that way because .gov has too much control over operations.  Keeping the service private is probably the best way to go.  We have all seen what happens with public utilities.

If there is money to be made, private industry will find it!  Kind of like residential solar.

[tggzzz]

Besides, it isn't just the plug/socket, it is everything else in a charger.

Glue it to the heatsink and pot it. Except for the mains to electronics connection, but no doubt there are good standards and solutions for under ground mains connections already.


A ticket dispenser has UI and mechanical components. A minimal charger will just have a status LED and the connector exposed to humans (far more destructive than water).

A charger must have the ability to read a payment device, authenticate credit availibility, debit someone's account, and communicate that to the user.

I would prefer to listen to the experience of someone used to working in/under roads than someone presuming it is easy. The last time I had that pleasure was, gulp, 42 years ago at BT Research Labs. Eye opening.

This is an engineering forum:  to advocate this method, one should include some quantitative estimates.

Capacitive charging at KW level has been done, but with large plates. If you can get away with a small mating surfaces depends on the structural properties of high permittivity ceramics.

Numbers please, e.g. voltages, currents, components, x/y/z dimensions.

[rstofer]

Then we had Rural Electification starting in 1935.  The money came from .gov but the end result was private.

https://livingnewdeal.org/glossary/rural-electrification-administration-rea-1935

How could anybody afford a 10 mile overhead circuit just to light a lightbulb?  They still had ice men bringing ice on a cart pulled by horses, what did they know about the Internet?

Side issue, I don't remember which relative but I do remember the ice man and the ice box in the kitchen.

Along came telephones.  How could we ever afford to wire the country?  We did it anyway...

Gas heating (and, earlier, gas lighting) with millions of miles of underground piping.  How could we ever afford something like that?  We did it anyway...

Eisenhower's interstate freeway system.  How could we ever afford freeways across the country?  We did it anyway.  National security provided some of the incentive.  And is wasn't terribly expensive at $114 billion ($558 billion today).

https://en.wikipedia.org/wiki/Interstate_Highway_System

Sure, these were large projects but they got done.

[tom66]

Zero surprise here! I only mentioned a (very) few places I could think of that I had been to

tom66 lists his location as "Cambridgeshire". Having lived there I would characterise it as

• a few small old bits
• lots of new bits
• lots of space, even in the old bits
• bloody boring, except for Ely and Cambridge centres

In other words it does not represent typical UK townscapes.

Given that, it isn't surprising if tom66 (and some people from the US on other fora) don't understand the impracticalities of their vision in "other places". Dismissing other people's completely valid experiences of "other places" does not reflect well on them or their position.

tom66 spent most of his student life in Leeds and used to park on a terraced street near Headingley Stadium with a small car.  (Match days were not fun - do not move your car, you will not be able to park again.) tom66 also grew up in Hampshire in a small village with mostly street parking.  Currently I do have a driveway (it was a non-negotiable requirement when buying the house) but probably not enough space for a second car without remodelling the drive somewhat so when we do have two electric cars we will just alternate charging requirements between these cars.  The street I currently live on is alike many in semi-urban England - a mix of street parking and driveways, representative of the "25% of people*" not having access to off street parking.  I look at my street as being pretty representative of most, a mix of detached, semi-detached, terraced and bungalows, mostly built before the 1950's before cars were very popular, but actually not that difficult to serve for charging requirements.

I do not currently live in Cambridgeshire, I moved to Northamptonshire six months ago.  I would describe Northamptonshire as one of the most 'normal' counties I have lived in.  It very much just looks like England.

I do not see street charging for EVs as unsolvable but like many problems it will need solutions appropriate to the area. Pavement gulleys (and sure, let's fine people who leave their cables out, I'm absolutely okay with that, but let's also fine people who park unnecessarily on the footway, too), pop up chargers, small posts, lamppost charging. and for those who have it, charging at home.  Nothing about this is impractical, especially given there's at least 10-15 years before EVs become even a significant proportion of total vehicles on the road, and if you look at bigger cities the solutions are already appearing.

I'm also not sure exactly what your proposed alternative *is*, if your assumption is EVs cannot work for the vast majority due to charging headaches.  We cannot continue to burn petrol, because climate change is a thing, most people do depend on their car so public transport alone won't pick up the slack, so we do have to figure this out.  So, what, do you want to see hydrogen cars instead, because those have worse infrastructure requirements, and don't give 50-75% of people the ability to 'refuel' at home.  There are so many more things about hydrogen which are more difficult than getting 2kW to a car to charge overnight, and let's not forget the poor efficiency of these vehicles making any "grid load" far worse for hydrogen if renewable energy would be used.  It might be a solution for some applications, but for cars, it is not.  Hybrid vehicles might make some sense in the short term if battery constraints existed, but so far those aren't rearing their ugly head, batteries have only fallen in cost every year since the Leaf.   Note that Toyota's position of hybrids and hydrogen is in part due to their poor Li-Ion battery production capacity; something Tesla, the Germans, and the rest of the American auto industry all have a reasonable head start on, and a market China really stands to compete in, too.

*25% is better than the earlier 50% figure I'd quoted from the AA, but they were probably not including anything but driveways in their estimation.  Driveways are the easiest problem to solve for EV charging, but off-road parking in a shared lot is probably the second easiest, though requires more negotiation between parties (LA, landlord/land owner/etc.)

[tggzzz]

Consider a much simpler problem: a machine to dispense car parking tickets for parking spaces on the road. Characteristics: above ground, one every 100m or so, low power. Given the proportion of those simple machines that are out of order when you try to buy a ticket, the reliability of roadside chargers is likely to be, um, less than acceptable.

Follow the money!  In the case of the ticket dispenser, the money goes to the City and repair is controlled by City employees.  They clearly don't give a damn at any level.

Hopefully, charging points will be owned by private enterprise and they have a profit motive for keeping them ALL working.  After all, there is no return on their capital investment if they can't sell kWh.

The .gov should clear the roadblocks but the work/return should all be private enterprise.

We'll get into the discussion of 'red-lining' (crossing out entire neighborhoods) later but that's one of those incentive deals where .gov can actually make a contribution to grease the skids.

In a lot of ways, charging points could be a public utility.  I wouldn't want to see it go that way because .gov has too much control over operations.  Keeping the service private is probably the best way to go.  We have all seen what happens with public utilities.

If there is money to be made, private industry will find it!  Kind of like residential solar.

And there we have the core political philosophy. Government is inefficient and industry isn't.

While that may be true in the US, over here people are people whether they are employed by the government or autocrats. The main difference here is that the people can get rid of politicians but they can't get rid of autocrats. I believe Comcast is a poster child for that, but I'm sure there are others like patent troll companies and those that jack up the cost of old drugs by 10000% just because they can.

Over here we have been privatising public utilities since the 80s. Most of the results have been dismal, partly because the same people are doing the same job, partly because the autocrats siphon off money into their own pockets, and partly because that is what all private monopolies do.

[rstofer]

A charger must have the ability to read a payment device, authenticate credit availibility, debit someone's account, and communicate that to the user.

Gas pumps already do this and have for a long time.

I would prefer to listen to the experience of someone used to working in/under roads than someone presuming it is easy. The last time I had that pleasure was, gulp, 42 years ago at BT Research Labs. Eye opening.

But it is already known how to do this.  I don't know how but there are thousands of people who do.  This is just a tiny detail.  BTW, we did that at a company I worked for when we wanted to run an 8" chilled water line among 3 buildings without tearing up the lawn and buried utilities.  Worked well!

[tom66]

A charger must have the ability to read a payment device, authenticate credit availibility, debit someone's account, and communicate that to the user.

Not necessarily with Plug and Charge which is something newer EVs should support.  (It should have been there from day-zero, but there are alternatives like an in-cable smart meter, as used by Ubitricity, that make the charging port very simple indeed.)

[nctnico]

A charger must have the ability to read a payment device, authenticate credit availibility, debit someone's account, and communicate that to the user.

Gas pumps already do this and have for a long time.

Yes and no. EV charging stations typically don't accept debit or credit cards. OTOH every manned / unmanned gas pump does. For some reason companies that run EV chargers deemed it necessary to invent their own cards which are not interchangeable.

[tom66]

Yes and no. EV charging stations typically don't accept debit or credit cards. OTOH every manned / unmanned gas pump does. For some reason companies that run EV chargers deemed it necessary to invent their own cards which are not interchangeable.

Err... how many have you used?  Every new DC charger in the UK has to accept contactless payment, and a good majority of older ones do already.  (They don't require PINs so no keypad is needed, just a contactless reader.)  This also appears to the way the EU is going.  The vast majority don't bother with RFID cards any more because yeah, it is a hassle, they just work with mobile apps.  These apps vary from "dreadful" (BP Pulse, really, just best avoided) to "really good" (PodPoint).  Perhaps expecting an oil company to make good EV charging infrastructure is foolish.

The ideal outcome I would see for EV charging is it being an extension of your home electricity bill.  The electrons are all the same after all.  Just pay the service fee for the charger  (per kWh or maybe, for DC charging, a fixed fee)  and you get whatever rate your supplier negotiated for your usage.  And the service fees should be fixed to some reasonable rate covering normal wear and tear of the charging equipment.

[Marco]

A charger must have the ability to read a payment device

At the point you're filling the entire country with chargers, it's far cheaper to just give people without a mobile phone one with a free sim, which can only be used to access a payment portal. App can have a bluetooth mode with an in-app reserve for when mobile data is down.

Regardless of any other aspect of the design, it will massively simplify the charger.

Numbers please, e.g. voltages, currents, components, x/y/z dimensions.

Papers for existing prototype systems you can look up yourself.

Lets say a 4 plate system with plates 10x10cm. Then with 2 mm of 100x relative permittivity insulator the series capacitance would be around 2 nF. At 100 kHz that's an impedance of 5k. Lets assume simple impedance matched resistive load to get some ballpark figure, 1800V RMS required for 3 kW. Ballpark doable with a high permittivity insulator, without it not so much.

[mikeselectricstuff]

A charger must have the ability to read a payment device, authenticate credit availibility, debit someone's account, and communicate that to the user.

Gas pumps already do this and have for a long time.

Yes and no. EV charging stations typically don't accept debit or credit cards. OTOH every manned / unmanned gas pump does. For some reason companies that run EV chargers deemed it necessary to invent their own cards which are not interchangeable.

Rapid chargers mostly do these days. AC chargers not usually, as the cost is disproportionate.

[TimFox]

Again in the US, the Federal Government as part of its infrastructure program will require rationalization of payments at charging stations, specifically to accept normal credit/debit cards and not require a mobile-phone app.
(From same newspaper article about negotiations with Tesla about opening their charging stations to other makes of EV.)

[Marco]

European market is big enough not to have to worry about that.

[TimFox]

A charger must have the ability to read a payment device

At the point you're filling the entire country with chargers, it's far cheaper to just give people without a mobile phone one with a free sim, which can only be used to access a payment portal.

Regardless of any other aspect of the design, it will massively simplify the charger.

Numbers please, e.g. voltages, currents, components, x/y/z dimensions.

Papers for existing prototype systems you can look up yourself.

Lets say a 4 plate system with plates 10x10cm. Then with 2 mm of 100x relative permittivity insulator the series capacitance would be around 2 nF. At 100 kHz that's an impedance of 5k. Lets assume simple impedance matched resistive load to get some ballpark figure, 1800V RMS required for 3 kW. Ballpark doable with a high permittivity insulator, without it not so much.

1800 V rms across 2 mm of air is about (1250 V peak)/mm, which is OK for dry air (3 kV/mm).
However, if you have 2 mm of high-k ceramic and a thin air gap, the E field in the air gap is multiplied by the dielectric constant of the ceramic (maybe 10?).
This a usual problem in high-voltage engineering--avoiding air gaps and bubbles with dielectric insulators.

[tom66]

Problem is converting AC electricity to 100kHz then transmitting it across a gap then rectifying it back into DC to charge the battery will add losses. Presumably you could modulate the generating side to track the battery voltage, but if not, include a DC-DC converter in that with further losses.  Also you will need bidirectional comms.

So the convenience your solution offers needs to be >> than a simple type2 cable, for which the connector and cable hardware costs under 100 euros in bulk.

[Marco]

It's not for convenience, it's to be able to put the charging connector on the curb and take up no room.

I'm not saying it's _the_ solution, I'm just saying in high density older European towns every solution to curb side charging has a ton of problems. The simple solution of just putting a charging pole every 6 meters will not work, not because of material cost but simply because it will make the street completely unusable. Every not simple solution is pretty far out there.

PS. all the pop up charger test runs don't seem to have UI either, so presumably all app based. But even popup chargers will take up a ton of extra space on the curb, unless there's so many of them they can pop up in between cars.

[tggzzz]

A charger must have the ability to read a payment device, authenticate credit availibility, debit someone's account, and communicate that to the user.

Gas pumps already do this and have for a long time.

There are indeed tens of thousands in nice roomy dry above ground cabinets.

That's very different to tens of millions buried below ground in cramped and wet holes.

I would prefer to listen to the experience of someone used to working in/under roads than someone presuming it is easy. The last time I had that pleasure was, gulp, 42 years ago at BT Research Labs. Eye opening.

But it is already known how to do this.  I don't know how but there are thousands of people who do.  This is just a tiny detail.  BTW, we did that at a company I worked for when we wanted to run an 8" chilled water line among 3 buildings without tearing up the lawn and buried utilities.  Worked well!

My point remains.

[tggzzz]

Yes and no. EV charging stations typically don't accept debit or credit cards. OTOH every manned / unmanned gas pump does. For some reason companies that run EV chargers deemed it necessary to invent their own cards which are not interchangeable.

Err... how many have you used?  Every new DC charger in the UK has to accept contactless payment, and a good majority of older ones do already.  (They don't require PINs so no keypad is needed, just a contactless reader.)  This also appears to the way the EU is going.  The vast majority don't bother with RFID cards any more because yeah, it is a hassle, they just work with mobile apps.  These apps vary from "dreadful" (BP Pulse, really, just best avoided) to "really good" (PodPoint).  Perhaps expecting an oil company to make good EV charging infrastructure is foolish.

The ideal outcome I would see for EV charging is it being an extension of your home electricity bill.  The electrons are all the same after all.  Just pay the service fee for the charger  (per kWh or maybe, for DC charging, a fixed fee)  and you get whatever rate your supplier negotiated for your usage.  And the service fees should be fixed to some reasonable rate covering normal wear and tear of the charging equipment.

Excellent. I'll charge my car from my neighbour's charging point.

[tggzzz]

A charger must have the ability to read a payment device

At the point you're filling the entire country with chargers, it's far cheaper to just give people without a mobile phone one with a free sim, which can only be used to access a payment portal. App can have a bluetooth mode with an in-app reserve for when mobile data is down.

Regardless of any other aspect of the design, it will massively simplify the charger.

Numbers please, e.g. voltages, currents, components, x/y/z dimensions.

Papers for existing prototype systems you can look up yourself.

It is your assertion, so presumably you have knowledge of the existing literature and products. Demonstrate that knowledge.

Lets say a 4 plate system with plates 10x10cm. Then with 2 mm of 100x relative permittivity insulator the series capacitance would be around 2 nF. At 100 kHz that's an impedance of 5k. Lets assume simple impedance matched resistive load to get some ballpark figure, 1800V RMS required for 3 kW. Ballpark doable with a high permittivity insulator, without it not so much.

1.8kV near water (and in water when something fractures) is not something to leave lying in pavements. Especially if there is only a thin shatterable ceramic between people and the electrode.

At 100kHz/3kW there will be significant conversion inefficiencies from 50Hz (or DC). Just when you need water to cool such a converter, there will be a drought.

The difference between theory and practice is that in theory there is no difference, whereas in practice there is.

So, let's see the specs of the prototypes, and how well they performed outside the lab.

[tggzzz]

It's not for convenience, it's to be able to put the charging connector on the curb and take up no room.

I'm not saying it's _the_ solution, I'm just saying in high density older European towns every solution to curb side charging has a ton of problems. The simple solution of just putting a charging pole every 6 meters will not work, not because of material cost but simply because it will make the street completely unusable. Every not simple solution is pretty far out there.

PS. all the pop up charger test runs don't seem to have UI either, so presumably all app based. But even popup chargers will take up a ton of extra space on the curb, unless there's so many of them they can pop up in between cars.

I'm glad someone acknowledges the physical impracticality of solutions dreamed up by others

If something pops up between cars, then sooner rather than later it either won't pop up or will pop up under cars!

[tggzzz]

Zero surprise here! I only mentioned a (very) few places I could think of that I had been to

tom66 lists his location as "Cambridgeshire". Having lived there I would characterise it as

• a few small old bits
• lots of new bits
• lots of space, even in the old bits
• bloody boring, except for Ely and Cambridge centres

In other words it does not represent typical UK townscapes.

Given that, it isn't surprising if tom66 (and some people from the US on other fora) don't understand the impracticalities of their vision in "other places". Dismissing other people's completely valid experiences of "other places" does not reflect well on them or their position.

tom66 spent most of his student life in Leeds and used to park on a terraced street near Headingley Stadium with a small car.  (Match days were not fun - do not move your car, you will not be able to park again.) tom66 also grew up in Hampshire in a small village with mostly street parking.  Currently I do have a driveway (it was a non-negotiable requirement when buying the house) but probably not enough space for a second car without remodelling the drive somewhat so when we do have two electric cars we will just alternate charging requirements between these cars.  The street I currently live on is alike many in semi-urban England - a mix of street parking and driveways, representative of the "25% of people*" not having access to off street parking.  I look at my street as being pretty representative of most, a mix of detached, semi-detached, terraced and bungalows, mostly built before the 1950's before cars were very popular, but actually not that difficult to serve for charging requirements.

I do not currently live in Cambridgeshire, I moved to Northamptonshire six months ago.  I would describe Northamptonshire as one of the most 'normal' counties I have lived in.  It very much just looks like England.

In that case I find it remarkable (but not surprising) that you propose schemes that aren't practical in places that are familiar to you.

I do not see street charging for EVs as unsolvable but like many problems it will need solutions appropriate to the area. Pavement gulleys (and sure, let's fine people who leave their cables out, I'm absolutely okay with that, but let's also fine people who park unnecessarily on the footway, too),

That's a fail right there. If the police and courts don't have the time to fine people that obstruct pavements, then why do think they will have time to fine people that leave trip/grounding hazards across pavements?!

Wake up and smell the coffee!

pop up chargers, small posts, lamppost charging. and for those who have it, charging at home.  Nothing about this is impractical, especially given there's at least 10-15 years before EVs become even a significant proportion of total vehicles on the road, and if you look at bigger cities the solutions are already appearing.

The impracticalities have been stated, and some others on this forum recognise them. Horses, water, drink.

I'm also not sure exactly what your proposed alternative *is*, if your assumption is EVs cannot work for the vast majority due to charging headaches. We cannot continue to burn petrol, because climate change is a thing, ...

And there's the failure of your critical thinking analysis.

You incorrectly presume I don't support EVs.
You incorrectly presume I have a solution to intractable problems.
And you want me to respond to strawman arguments. Not going to happen.

most people do depend on their car so public transport alone won't pick up the slack, so we do have to figure this out.  So, what, do you want to see ...

What do I want to see?...

Like MacKay, I don't care which solutions are adopted, provided they add up and work in practice.

I get sick and tired of people thinking (I use that term loosely) that because the easy 10% can be cherry-picked, then that means the remaining 90% is solvable.

I also get sick and tired of people finding it acceptable to leave 10% (?25%?, whatever) of people severely disadvantaged. I know "I'm all right Jack" libertarianism is fashionable, but I find it loathesome.

*25% is better than the earlier 50% figure I'd quoted from the AA, but they were probably not including anything but driveways in their estimation.  Driveways are the easiest problem to solve for EV charging, but off-road parking in a shared lot is probably the second easiest, though requires more negotiation between parties (LA, landlord/land owner/etc.)

Off-road parking is not a problem w.r.t. installing chargers - it is low-hanging fruit that will be cherry-picked.

Powering it is less easy, e.g. in West London where the grid infrastructure is already insufficient for building new housing developments. Upgrading that distributed grid infrastructure is a major challenge, very expensive and very disruptive.