Ponty
pfm Member
I was thinking more from a national charging infrastructure perspective. As you say, it’s a lot of waste.
Should I buy an EV - real world advice needed.
- Thread starter beammeup
- Start date
I was thinking more from a national charging infrastructure perspective. As you say, it’s a lot of waste.
gingermrkettle
Deep vein trombonist
Or converting 60-80% of the fuel you buy into heat rather than motion through thermodynamic losses.
Ponty
pfm Member
Sure, but you receive the fuel you actually pay for at the pumps. On the basis of these ‘efficiencies’, for the mileage you get, either petrol is too cheap (despite being very heavily taxed) or electricity too expensive.
EV 10% charging losses
You need to look at efficiency overall, not just concentrate on one or two aspects. That's where hydrogen falls down at the moment. It costs a lot more to make and distribute than plain old electricity for example. Also H2 tanks have a finite life as the stuff damages the containers and pipes that flows through it. With engines burning hydrocarbons (diesel, petrol, kerosene) you have huge thermodynamic loss and you still have inefficiencies from extraction, refinement, distribution and thermal losses.
Cobalt
You know that cobalt is used in hydrocarbon refining process?
Many modern batteries don't use the stuff any more.
You need to look at efficiency overall, not just concentrate on one or two aspects. That's where hydrogen falls down at the moment. It costs a lot more to make and distribute than plain old electricity for example. Also H2 tanks have a finite life as the stuff damages the containers and pipes that flows through it. With engines burning hydrocarbons (diesel, petrol, kerosene) you have huge thermodynamic loss and you still have inefficiencies from extraction, refinement, distribution and thermal losses.
Cobalt
You know that cobalt is used in hydrocarbon refining process?
Many modern batteries don't use the stuff any more.
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gingermrkettle
Deep vein trombonist
And of course, as anyone who has ever read a cable thread on here will now, cable losses are a function of current so the 10% quoted is likely to only be relevant for the fastest DC charging. Home charging losses (most relevant for most owners) will be significantly lower.
You need to look at it holistically. IC engines waste vast quantities of energy as heat at the point of use. EVs much less. EVs waste a certain amount during charging. Certainly. Nothing comes for free. Fuel doesn't appear magically at the petrol pump.
Charging losses are in many cases inherent to the technology. Traditional lead acid batteries for example are only about 70% efficient. That means that for every 100 kWh you put into the battery on, say, a fork lift, you only get 70 kWh back out as motive power. If modern cars are 90% efficient, so much the better. But nothing is for nothing. Even my bicycle doesn't convert 100% of my pedal effort to the wheel for propulsion. Don't even ask how efficient my fat a*se is at converting porridge to actual leg effort.
Richard Lines
pfm Member
Good afternoon all,
Surely it cannot have come as a surprise to anyone here that charging a battery is a less than 100% efficient process?
My Tesla PW2 has a round trip efficiency of 89.5%. My PylonTechs charge at about 92% efficiency.
Regards
Richard
Surely it cannot have come as a surprise to anyone here that charging a battery is a less than 100% efficient process?
My Tesla PW2 has a round trip efficiency of 89.5%. My PylonTechs charge at about 92% efficiency.
Regards
Richard
Tony Lockhart
Avoiding Stress, at Every Opportunity
Maybe, maybe not, but at least more people now know roughly what the figures are.
Darth Vader
From the Dark Side
Charge and discharge of a battery is a chemical process and what you actually get in terms of efficiency is dictated by chemical thermodynamics.
Over simplifying the energy going in or coming out of a battery is approximately E=H+G -x. The two important terms here are H (enthalpy) and G (Gibbs free energy). G is the energy that can do useful work and H is wasted as heat. That x bit is rather small and involves Entropy and I'm going to ignore this.
It so transpires that if you take the energy infinitely slowly you'll get 100% G. The opposite is also true and if you took the energy as fast as possible you'd get 100% H all as heat. So the faster you charge a battery and the faster you take the charge out the hotter the battery becomes and the less energy you have to do useful work like driving a motor and moving a car.
DV
Over simplifying the energy going in or coming out of a battery is approximately E=H+G -x. The two important terms here are H (enthalpy) and G (Gibbs free energy). G is the energy that can do useful work and H is wasted as heat. That x bit is rather small and involves Entropy and I'm going to ignore this.
It so transpires that if you take the energy infinitely slowly you'll get 100% G. The opposite is also true and if you took the energy as fast as possible you'd get 100% H all as heat. So the faster you charge a battery and the faster you take the charge out the hotter the battery becomes and the less energy you have to do useful work like driving a motor and moving a car.
DV
Somafunk
pfm Member
I took out a MG4 EV XPower today for a decent 50 mile drive, nice car and bloody quick off the mark with really impressive handling and road manners, brakes are just as impressive as acceleration, coped with Galloway roads very well but the driving position totally ruled it out for someone like myself with spms, had to get pulled out by a mate and it took 10 mins before I could stand. So I ended up buying what I came to have a look at which was the MG HS Trophy DCT. I sat in it whilst in the showroom, adjusted the electric seat to a position that felt comfortable and that was the sum total of my test drive, ordered one in Urban Grey using the motability scheme with no downpayment, should be ready in a fortnight and I can hand back my current motability vehicle which is a VW Tiguan 2.0 DCT.
Wanted the MG4, left with a fridge.
Wanted the MG4, left with a fridge.
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Dave H.
Revolutionary relativist
For what it's worth I have bought an EV, which will be delivered tomorrow (a couple of years old IPace).
This represented a minor bout of madness, since the car I already have is a great car (Skoda Superb iv). But I decided that an EV was the way to go, and my existing car was never going to be worth as much as a part ex in the future as it is right now, so better to jump sooner than later. And it's done now!
On the off chance that anyone here has some rather specific experience, I'd be interested in how others may have got on with charging at the Beaconsfield services, off J2 of the M40.
I semi-regularly go from the midlands to a place in London near Heathrow, and those services seem a good candidate for a charge/coffee/break. So if there are always lots of available chargers, or if there are always hour long queues, it'd be good to know.
This represented a minor bout of madness, since the car I already have is a great car (Skoda Superb iv). But I decided that an EV was the way to go, and my existing car was never going to be worth as much as a part ex in the future as it is right now, so better to jump sooner than later. And it's done now!
On the off chance that anyone here has some rather specific experience, I'd be interested in how others may have got on with charging at the Beaconsfield services, off J2 of the M40.
I semi-regularly go from the midlands to a place in London near Heathrow, and those services seem a good candidate for a charge/coffee/break. So if there are always lots of available chargers, or if there are always hour long queues, it'd be good to know.
Firstly I’d recommend getting ABRP (a better route planner), setting the parameters after a bit of thought (charge once, charge often, minimum acceptable battery state before stopping and so on) and see what comes back. It is a very good piece of software.
Secondly, try to change the ’single long stop’ mindset to one of ‘if I’m stopping I’m charging’ to several short stops. EV charging is not linear and charging from say 20% to 50% is often way faster than from 50% to 70%. A couple of charges will often save time over a single longer charge.
If you try to manage the EV like it was an ICE it will cause frustration.
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gingermrkettle
Deep vein trombonist
Bought an iPace in New Malden recently and did the journey the other way, the charging speed on the Ionity ones was good but there was a bit of a (good natured) queue on a Saturday afternoon.
The contactless payment wasn't working when I was there but payment through the website seemed to work fine. Not sure about the Gridserve ones though.
That specific enough?
tones
Tones deaf
The other aspect is that we dare not stop making cars, because so many industries (and so many jobs) depend on it, far beyond the people banging the shapes out of bits of metal - tyres, upholstery, paint and (increasingly) electronics. If all car manufacture were to cease tomorrow, we'd be looking at economic disaster and endless industrial strife. This situation has crept up on us slowly, before we realised the climatic consequences of our actions, so any reversal will need to be equally slow and very well coordinated. Given our various governments' abilities for forward planning beyond getting themselves re-elected, I am not optimistic.
cutting42
Arrived at B4 Hacker Ergo
Very good points on charging strategy and a technique I also use on long journeys. I recently did a 300 mile trudge and charged 3 times but only 10 mins each stop while I attended to bio needs. Never felt like I was waiting to charge.
I think that's the smart strategy. Treat it like an IC E car, it won't work. Top it up as and when you get the opportunity, now you're talking.
Dave H.
Revolutionary relativist
Interesting. In my case then, next time I need to do the journey I may stop in both directions at the (open to other brands) Tesla charging points near Banbury.
I think they’re actually cheaper than most service station places anyway, as well as faster.