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Charging EVs - Brit_in_Germany

I see that Andrew Brady believes that chargers are 100% efficient. According to his maths, a 70 kWh battery needs 70 kWh of electricity to charge it.

www.honestjohn.co.uk/askhj/answer/179473/average-c...r-

For our Zoe, I reckon on about 50 kWh to put in 35 kWh or so. Apart from the losses in the charger, there are also losses in the car's inverter together with the battery's losses. D.c. charging is more effecient but usually has a higher unit price as the charger has to convert the a.c.

Charging EVs - badbusdriver

Another EV charging thread?

Charging EVs - Brit_in_Germany

Where?

Charging EVs - badbusdriver

Where?

ev---charger-chaos

Err, that one. 182 posts and counting!

Charging EVs - pd

There are losses, certainly on an AC feed but those figures sound excessive.

Might be worth getting charger and/or car checked. Is it a consistent loss a across all chargers?

Charging EVs - Brit_in_Germany

This is charging using a 3-phase, 11 kW charger. Looking at the information on the web, at 11 kW, the efficiency should be around 87% but decreases as the charging power decreases so that at 2 kW it is only around 60%.

As the battery approaches full charge, the charging power is throttled back, so now with our electricity price exploding, I will pay more attention, setting the charging to stop at 80% and see if that makes a significant difference.

Charging EVs - mcb100
Is that vis a domestic wall socket or a dedicated charge point?
Lots of variables come into play - length of cable, diameter of cable, ambient temperature, SOC at start and finish of charging.
DC charging is more efficient, and the higher the voltage the better. As we (eventually) transition to 800v architecture the higher voltage means smaller current and less heat build up.
If you’re getting losses to your magnitude, imagine what it’s like for those on a 120v supply…
Charging EVs - Andrew-T
Lots of variables come into play - length of cable, diameter of cable, ambient temperature, SOC at start and finish of charging. DC charging is more efficient, and the higher the voltage the better.

This reminds us all of an important difference between electricity and petrol (or diesel). At least once the fuel is in the tank your only worry is slow evaporation ! Everything that leaves the pump enters the tank, assuming you are careful. With electricity there are losses almost everywhere.

Charging EVs - RT
Lots of variables come into play - length of cable, diameter of cable, ambient temperature, SOC at start and finish of charging. DC charging is more efficient, and the higher the voltage the better.

This reminds us all of an important difference between electricity and petrol (or diesel). At least once the fuel is in the tank your only worry is slow evaporation ! Everything that leaves the pump enters the tank, assuming you are careful. With electricity there are losses almost everywhere.

Plenty of losses with petrol - mainly in the form of wasted heat.

Charging EVs - John F

Rarely mentioned are the huge losses at the power stations (basically big steam engines) which generate the power for EVs when the wind doesn't blow and the sun doesn't shine. Even more losses from the fizzing wires carrying that power to the garage socket.

Charging EVs - Terry W

Efficiency of gas turbines generating electricity is ~60%. Transmission losses are 8-10%. Comparing overall efficiency of ICE and EV based on 100 "units" of energy:

EV - 40% generation losses , 8% transmission losses , 90% charging efficiency = 50

ICE - 30% ICE efficiency = 30

This is very simplistic but materially correct - using gas to generate electricity is 60 - 70% more efficient than using a fossil fuel for an ICE directly.

Improving assumptions to include distribution infrastructures, EV motor efficiency etc etc will likely still produce the same outcome, although the absolute benefit may differ.

Fundamental point - green energy can power EVs, but only with difficulty (eg: hydrogen generation) power an ICE.

Charging EVs - Bromptonaut

Rarely mentioned are the huge losses at the power stations (basically big steam engines) which generate the power for EVs when the wind doesn't blow and the sun doesn't shine. Even more losses from the fizzing wires carrying that power to the garage socket.

A system based on renewables needs infill to cover fluctuation in renewable outputs.

That's an argument for greener infill not some sort of Top Trump against the 40% renewables already contribute and the greater amounts they will add in future.

Charging EVs - Terry W

The average ICE is ~30% efficient in turning the potential energy in the fuel into motion. The rest is lost through heat (exhaust, engine cooling) and friction.

A better measure of efficiency is "well to wheel" which takes account of losses through the complete process - refining, electricity generation, transport, vehicle efficiency etc.

Overall it seems EV is judged better than ICE - complex assumptions means that a precise answer would be an exercise in spurious accuracy. Example - how to compare the efficiency of a electricity distribution network vs fuel tankers.

It is also the case that EV can use green energy for generation, an ICE mainly uses the products of an oil well (+possibly gas and hydrogen)

Charging EVs - Andrew-T

<< Plenty of losses with petrol - mainly in the form of wasted heat. >>

Come on, you know what I mean - your 'wasted heat' occurs when fuel is being used. The losses I mention occur while transferring the 'fuel'.

Charging EVs - Sofa Spud
Lots of variables come into play - length of cable, diameter of cable, ambient temperature, SOC at start and finish of charging. DC charging is more efficient, and the higher the voltage the better.

This reminds us all of an important difference between electricity and petrol (or diesel). At least once the fuel is in the tank your only worry is slow evaporation ! Everything that leaves the pump enters the tank, assuming you are careful. With electricity there are losses almost everywhere.

While there might be no losses between pump and tank, around two thirds of the energy released by combustion in the engine is wasted as heat, meaning the engine is only about 33% efficient. An electric car is about 90% efficient in operation.

Charging EVs - Engineer Andy
Lots of variables come into play - length of cable, diameter of cable, ambient temperature, SOC at start and finish of charging. DC charging is more efficient, and the higher the voltage the better.

This reminds us all of an important difference between electricity and petrol (or diesel). At least once the fuel is in the tank your only worry is slow evaporation ! Everything that leaves the pump enters the tank, assuming you are careful. With electricity there are losses almost everywhere.

While there might be no losses between pump and tank, around two thirds of the energy released by combustion in the engine is wasted as heat, meaning the engine is only about 33% efficient. An electric car is about 90% efficient in operation.

The losses between power station fuel input and usage by the vehicle (including generation and transmission) compensate for that. It's why local power generation (especially at home/work via PV panels) is better - it cuts out all those intermediate losses.

The difference is also less in winter (as it is between petrols and diesels) because the waste heat of the ICE vehicle is utilised to heat the cabin, whereas the EV has to utilise extra battery power.

Charging EVs - mcb100
‘The difference is also less in winter (as it is between petrols and diesels) because the waste heat of the ICE vehicle is utilised to heat the cabin, whereas the EV has to utilise extra battery power.’

Have a look at heat pumps, becoming more prevalent now on EV’s.

www.gridserve.com/2022/12/13/what-is-a-heat-pump-a.../

Charging EVs - Engineer Andy
‘The difference is also less in winter (as it is between petrols and diesels) because the waste heat of the ICE vehicle is utilised to heat the cabin, whereas the EV has to utilise extra battery power.’ Have a look at heat pumps, becoming more prevalent now on EV’s. www.gridserve.com/2022/12/13/what-is-a-heat-pump-a.../

Heat pumps only really are efficient in heating mode when the temperature outside isn't that cold - i.e the COP will be mainly around 1-1.5 (electrical energy in --> heat output) when the ambient tempertaure is near or below 0degC. It still requires electrical energy.

An ICE car will have more than enough waste heat to use to heat the cabin (several tens of kWs) due to the inehrrant inefficiency of the engine design. It's why diesel engined cars aren't so good at heating up the interior quickly as a petrol-engined one, as they are a decent amount more thermally efficient.

It probably makes more difference in summer when the heat pump's COP will be around 2-2.5 (best at around 4 in May and September when it's not too hot or cold) where the ICE car will obviously not be able to utilise that waste heat - quite the opposite in fact.

I wonder if anyone thought of making a small-scale steam-electric generator for ICE vehicles to use that waste heat? I did see a report recently though about a heat pump without any moving parts - literally like a solar panel but it just takes the heat and turns it into electricity, supposed about 30-35% efficient. Might be woth using on ICE cars (and other things) to save on electrical usage and thus fossil fuels.

Charging EVs - expat

I did see a report recently though about a heat pump without any moving parts - literally like a solar panel but it just takes the heat and turns it into electricity, supposed about 30-35% efficient. Might be woth using on ICE cars (and other things) to save on electrical usage and thus fossil fuels.

Would that be a Peltier device? Usually used for cooling but could be used for heating. Not very efficient but it has its uses.

en.wikipedia.org/wiki/Thermoelectric_cooling

Charging EVs - Engineer Andy

I did see a report recently though about a heat pump without any moving parts - literally like a solar panel but it just takes the heat and turns it into electricity, supposed about 30-35% efficient. Might be woth using on ICE cars (and other things) to save on electrical usage and thus fossil fuels.

Would that be a Peltier device? Usually used for cooling but could be used for heating. Not very efficient but it has its uses.

en.wikipedia.org/wiki/Thermoelectric_cooling

Looks similar in size/shape as in the report I read (can't remember where it was though). Perhaps whoever it was made some new advance.

Charging EVs - mcb100
But the end result is the same, smaller losses at a different point of the chain resulting in a greater overall efficiency.
Charging EVs - Mike Lanc

I do not have an EV, but understand that the Li batteries in them are never be allowed to fully discharge and should not be fully charged either. So, taking the 70 kWh battery, what is its effective capacity? For argument's sake, say 20% min to 80 % max would give us 56 useable units (kWh). On top of that is there must be some inefficency in the charging process. Your figures suggest that the charging process is only 70% efficient. On this basis, it would require 80 units of electricity to be pumped into the battery to give it 56 useable units. How far will these 56 units take you and how much is that range affected by the time of year (Cabin heating and lighting must surely reduce winter range). According the the Korean gov, low temperature reduces the range of Tessla's by 50%. Only with that information and actual range data from the car will it be possible to work out the real fuel cost of an EV.

Charging EVs - Engineer Andy

Actually only using an EV between 20-80% charged (also the quickest reasonable charge profile, given most if not all slow down the charging rate as it nears 100%) means you only have 60% of the battery output as useful energy, which is 42kWh. You only charge it up to 80% and have to charge it up again when it reaches 20% charge left.

Got the link for the Korean government report? I'm also wondering if it puts tesla in a 'bad' light whilst puffing up the home-grown Hyundai/KIA, who make many rival EV cars.

Charging EVs - sammy1

Actually only using an EV between 20-80% charged (also the quickest reasonable charge profile, given most if not all slow down the charging rate as it nears 100%) means you only have 60% of the battery output as useful energy, which is 42kWh. You only charge it up to 80% and have to charge it up again when it reaches 20% charge left.

Got the link for the Korean government report? I'm also wondering if it puts tesla in a 'bad' light whilst puffing up the home-grown Hyundai/KIA, who make many rival EV cars.

Yes I came to much the same conclusion of useful range somewhere in the " charger chaos thread"

I too read in the press that S. Korea is to sue Tesla regarding its claims for the expected range of its cars in their very cold winter stating they are some 50% less

I also picked up that manufacturers of EVs for the UK market are cutting back production for this year mainly due to lack of demand blaming high prices.

Charging EVs - Terry W

Tesla are being sued by SK for $2.9bn for exaggerated range claims. Compare with VW dieselgate which cost them more than £30bn (mainly US and Germany). In proportion Korea/Tesla is a minor infringement (albeit probably justified).

Charging EVs - RT

Scotland puts back the date to end pure IC car sales to 2032 due to "concerns over how slowly the country’s charging infrastructure was progressing, coupled with how expensive it now is to run an electric car, given the high price of electricity"

https://www.autocar.co.uk/car-news/new- ... s-ban-2032

Charging EVs - Xileno

It doesn't surprise me, I always though these deadlines might start to slip. I'm probably not alone.

I wonder if it would be possible to by an ICE car after the deadline in Scotland and bring it back to England? For those that want of course...

I suspect the rest of UK will follow to maintain alignment.

Charging EVs - mcb100
I don’t think we’ve seen any legislation yet from Westminster, just a proposal.
Charging EVs - sammy1

It doesn't surprise me, I always though these deadlines might start to slip. I'm probably not alone.

I wonder if it would be possible to by an ICE car after the deadline in Scotland and bring it back to England? For those that want of course...

I suspect the rest of UK will follow to maintain alignment.

I was thinking along the same lines. You might well be able to import your ICE from any right hand drive country even outside Europe. Might be a possible business opportunity if the gov does not put the mockers on it!

Charging EVs - sammy1

Interesting article in the Telegraph today and also posted to MSN. James May on EVs he doubts if there will ever be enough chargers going forward as EVs become more dominant.

Charging EVs - martin.mc

The Autocar article says that the proposed date for Scotland's ban on new ICE sales is still 2030 and that 2032 was a typo. I wouldn't be surprised if the date was pushed back though by either Scotland or the whole of the UK. As mcb said it's only a proposal at the moment.

Edited by martin.mc on 12/01/2023 at 16:04

Charging EVs - Terry W

If in 7 years time, come 2030, the charging network is still a mess, range still a problem, and the government through a desire not to lose face stick with the ban on ICE:

  • the value of s/h ICE will rise as folk hang on to their much loved, fill it in 5 minutes, proven technology. No new ones to be had though
  • the cost of new EVs will fall as manufacturers with capacity greater than demand try to shift stock
  • the government invest lots of money in extra generation and distribution capacity in a desperate effort to prove they had it right all along

It doesn't atter whether the 2030 ban works well or not. It will make not the slightest real difference to personal transport until 2040 when the ICE cars sold during the next 7 years start to reach banger status and begin getting scrapped.

Charging EVs - Engineer Andy

If in 7 years time, come 2030, the charging network is still a mess, range still a problem, and the government through a desire not to lose face stick with the ban on ICE:

  • the value of s/h ICE will rise as folk hang on to their much loved, fill it in 5 minutes, proven technology. No new ones to be had though
  • the cost of new EVs will fall as manufacturers with capacity greater than demand try to shift stock
  • the government invest lots of money in extra generation and distribution capacity in a desperate effort to prove they had it right all along

It doesn't atter whether the 2030 ban works well or not. It will make not the slightest real difference to personal transport until 2040 when the ICE cars sold during the next 7 years start to reach banger status and begin getting scrapped.

It will, because car manufacturers cannot just switch back to R&D on and making ICE cars if the ban on new ones gets pushed back 5, 10 or even 20 years. We're alraedy seeing a big push into EVs and very little new ICE or hubrids entering the market during the past 3 years.

As a result, many people will be forced to choose between buying an EV, which likely won't be suitable or will have charging issues (network as you described), paying vastly more for said EV or the few ICE new cars left on sale, similarly paying hugely inflated prices for second hand ICE cars, or giving up and either continuing to run their old car or stopping driving altogether.

A much easier decision for the well-off than not, all caused by poor decision-making led by people who mean to fleece the less well-off to further enrich themselves, gain more power and keep the roads, skies and holiday areas abroad to themselves.

Rather like things were pre-WWII.

Charging EVs - Andrew-T

<< ... very little new ICE or hubrids entering the market during the past 3 years. >>

I like that idea - a wonderfully serendipitous typo !

Pity about the usual conspiracy theories that followed though.

Edited by Andrew-T on 13/01/2023 at 15:55

Charging EVs - Engineer Andy

<< ... very little new ICE or hubrids entering the market during the past 3 years. >>

I like that idea - a wonderfully serendipitous typo !

Pity about the usual conspiracy theories that followed though.

Yeah, the current climate is certainly maing the less well off so much welathier and the rich poorer, and the proposed law changes are designed to help just that by making EVs soooo affordable for us peasants to buy. Hold on a minute...

You don't subsidise people who can already afford something by fleecing all of us below then say sorry, no more subsidies once the new law kicks in banning the only thing we could previously afford!

They are doing exactly the same with gas boilers vs heat pumps.

I wonder who is investing in said tech whilst simultaneously whispering in politicians' ears to go that route in policy terms? Hmmm.

Currently a 'conspiracy theory regarding such things (and now quite a lot of other 'current events' it seems) appears to be turning into reality at an increasing rate, possibly down to between 6-12 months.

Charging EVs - Xileno

We don't want top open up that old can of worms again. Conspiracy theories in the other forum if needs must. This forum for motoring and this particular thread for EV Charging and closely related motoring issues please.