The EV fact thread

[Bobby Dazzler]

Also, keeping in mind the most people will only top-up rather than charge zero to full - in my use case, had I driven to work even day I would only need to charge once a week, from 50% to 80%.

My daughter is using our Fiat 500e to travel to work every weekday. As you suggest, she pops it on charge when the remaining range is very close to or less than the next day’s journey. If she has to go further afield without notice then she just uses a public charger on the way. She’s not held back by the baggage of driving an ICE car, so she’s quickly adapted to the right mindset. So much so that…

I’m sat with my daughter and Mrs D right now and we were just talking about how much fuel is in the car Mrs D will use tomorrow. Mrs D commented that it’s a shame that we can’t top it up at home (ICE). I replied that it’s only a 40 miles round trip round trip and so it should manage that even if the fuel light is on. My daughter said “What you have 40 miles reserve, that’s half of my range at this time of year, why do you need so much?!”

 

[Bobby Dazzler]

So 35 pumps - let's say 4 minutes per pump at 3 mins plus 1 min get in and out - then that's say 525 cars per hour.

And that right there is the problem with ICE. If everyone refuels at the same time then there aren’t enough pumps, and if we limit the number of cars refuelling at any one time to the number of available pumps then the underpinning infrastructure - oil extraction, pipelines, processing, distribution, storage, etc - simply cannot keep up with demand.

 

[190]

I am not an electrical engineer, but I am assuming that it's similar to how comms network work.

The 'bandwidth' figure that you see is (in most cases) not dedicated. There are things called 'burst mode' and 'dark fibre', managing demand.

Similarly, there's no need to be able to provide full capacity to all chargers at the same time.

I'm sure you are correct about that. No electrical distribution system expects to see maximum demand from all consumers. In designing the system they apply a diversity factor based on experience of the real peak demand.

As a relatable example my house has a 100 amp supply which is 24 kW but if every house fed from the substation was to attempt to draw 24kW the system would collapse long before that level of load was achieved. EV's aside they know that loads are much less even at peak times and they size the distribution system accordingly.

What EV charging will do is change the diversity factor from what it was before the advent of EV charging and the factor they need to use will be something they have to gradually learn from experience.

 

[Bobby Dazzler]

I am not an electrical engineer, but I am assuming that it's similar to how comms network work.

The 'bandwidth' figure that you see is (in most cases) not dedicated. There are things called 'burst mode' and 'dark fibre', managing demand.

Similarly, there's no need to be able to provide full capacity to all chargers at the same time.

I would hazard a guess that 20 stalls with 250Kw capacity will not need a 5kW supply. More like around 3-4kW supply will do.

This is because a scenario of 20 cars charging at 250kW is not only unlikely, in fact it's impossible.

Firstly, not all cars are capable of charging at the highest speed. Then, the highest charging speed is only achieved with a warm battery, and so some cars will start slower until the battery has warmed up. Then, cars being charged beyond the 80% limit will slow down the charging. And last, out of 20 cars, some will be at various staging of parking up and getting ready to connect, while others will be busy disconnecting and driving out of the bay. In fact, 20x250kW will never ever happen.

I am willing to bet that the trunk capacity to these charging hubs is less than the total nominal capacity - it just doesn't make sense to design it any other way (unless you over spec the trunk supply in order to support future expansion and future upgrades).

+1

Petrol pumps in the UK have a flow rate up to 50 litres per minute although actual pump speed varies. If all pumps served at their maximum speed there is insufficient infrastructure behind to keep pace. That’s fine though because it’s a theoretical scenario which hardly ever happens - when it does and there’s a run in the pumps, then it’s absolute chaos for days or weeks!

 

[poormansporsche]

Well, I risked the 110 mile round trip "Dog Teeth Cleaning Run" in the Leaf today. I topped up at home for a couple of hours to get the battery to 95% and the car nice and toasty. The range was showing 130 miles which I know is bo££ocks in the cold. The trip is 90 % motorway and as I had the Dogs in the car, I "poodled" (sorry couldn't resist it ) along at 60 mph. Made it to my destination with 49% remaining. I made it home with 10% battery remaining and a range of 10 miles. I would never let a ICE car drop that low but knowing all you have to do is get home and the car will be "full" again next time you get in it is pretty cool, specially as I didn't have to leave the hounds whilst pumping or charging.

So a little bit more awkward than ice but not massively so.

 

[MikeInWimbledon]

Nissan started manufacturing in Europe for this reason, and specifically Sunderland as it came with the greatest incentives. A few decades later and Nissan in Sunderland is considered domestic in the context of this thread, despite having started out as a threat.

(Cough) Domestic: maybe. But Sunderland exports 80% of its production,

with only 20% remaining in the UK.

Your point is sound, but lets not understate how much Sunderland exports.

(We killed British car corporations with tax on their Headquarters. German and Japanese car manufacturers aren't so..... encumbered.)

 

[Dryce]

You’re a resourceful fellow so I bet you’ll be able to find out how long on average a car is parked in a park & ride car park.

My guess would be most of the working day. If my guess is even close to reality then would those cars need to be charged at more than a snail’s pace?

The journey pattern to/from a park and ride is likely to be on of multiple short journeys - not the sort that would necessarily use large service stations.

There isn't one size fits all to the pros and cons.

And charging at a snail's pace probably makes sense for a large number of potential EV users of park and ride facilities.

The problem is perhaps that fitting out a high proportion of parking bays - or even all bays - at P&R car parks with cheap slow speed charging infrastructure isn't as sexy as declaring that a token few parking bays have very high speed charging.

 

[Dryce]

And that right there is the problem with ICE. If everyone refuels at the same time then there aren’t enough pumps, and if we limit the number of cars refuelling at any one time to the number of available pumps then the underpinning infrastructure - oil extraction, pipelines, processing, distribution, storage, etc - simply cannot keep up with demand.

That's a different issue.

We have seen what happens if there is a fuel availability scare. All those parked up vehicles in the suburbs that sit with part full tanks all day suddenly have owners with the urge to fill them up 'just in case' and within a day or two the fuel distribution system gets messed up and there are queues at filling stations. And the reality is there is no actual real shortage- just a savage burst of intense purchase for the purpose of storage in parked cars.

But then we have an electricity generation system that is - on the back of the envelop - just about able to keep up with day to day weather shifts with cover from foreign supplies. Massive expensive investment in new reliable generation isn't going to be on tap for another few years and will be offset be decommissioning of power generation capacity that is being life extended as I type this.

Everything is fragile.

But mass switchover to EVs obsoletes one established vehicle energy distribution setup and expects on that needs years of construction that is not yet started to magically be available to take over.

 

[markjay]

That's a different issue.

We have seen what happens if there is a fuel availability scare. All those parked up vehicles in the suburbs that sit with part full tanks all day suddenly have owners with the urge to fill them up 'just in case' and within a day or two the fuel distribution system gets messed up and there are queues at filling stations. And the reality is there is no actual real shortage- just a savage burst of intense purchase for the purpose of storage in parked cars.

But then we have an electricity generation system that is - on the back of the envelop - just about able to keep up with day to day weather shifts with cover from foreign supplies. Massive expensive investment in new reliable generation isn't going to be on tap for another few years and will be offset be decommissioning of power generation capacity that is being life extended as I type this.

Everything is fragile.

But mass switchover to EVs obsoletes one established vehicle energy distribution setup and expects on that needs years of construction that is not yet started to magically be available to take over.

Energy companies have repeatedly said that there's no issue with electricity production for EVs, and that there's ample capacity.

The issues are further down the line from the power plants.

Firstly, distribution - not all areas have the required infrastructure to handle additional capacity from the power plants.

Then, chargers - these need to be installed, either at people's homes or in public areas (or both), and there are obvious commercial issues involved beyond the remit of the energy producers.