EV Discussion thread

thevilla

In the last few months this thread has become a fossil fuel promotion. I'm out!  Bye.

JKenH

That’s an interesting point of view - if you don’t want to participate in discussion you don’t have to (or even read the content here) but perhaps (some) others do as clearly over the weekend there was quite a lively debate. 

Perhaps, my article about cars being cleaner than horses falls into the category of promoting fossil fuels but other than that I don’t recall having promoted them myself (unless you consider the post about cars replacing horses to a fossil fuels promotion) although I have responded with an alternative POV to comments made by others who have been keen to criticise the fossil fuel and ICE industries. I would much prefer the thread focussed on EVs. The discussion on EV efficiency was taken completely off the rails by the introduction of a comparison with ICEvs. 

The intention was always for this thread to be a counterpoint to Mart’s BEV News thread celebrating EVs. As you will see from the opening post in this thread the intention, here,  was to encourage a wider debate on EVs with both good and bad points being discussed. Most of the “good news” is therefore posted on Mart’s thread which some might consider to be a “safe space” and hopefully a fossil fuel free zone.

michaels

JKenH said:

JKenH said:

I am amused by some of the calculations adopted by some organisations to push the efficiencies of EVs. In this particular example 10% of the energy is lost in charging, another 18% in the drivetrain , 3% in power train and cooling and 0-4% in auxiliary electric use. Regeneration then recovers 22% leaving a net loss of 9-13%. 

Losses incurred in charging are lost forever as are drivetrain, powertrain and electrical losses. Regeneration cannot recover these losses. Those 31-35%losses are gone forever. Neither can regeneration recover losses due to rolling resistance or drag. Regeneration can only convert kinetic energy back into electricity, i.e. recharging the battery by deceleration or by converting the kinetic energy acquired descending a hill and to acquire that kinetic energy you have either had to use the battery to get the car up to speed or to the top of a hill. 

Electric Vehicles Are Way, Way More Energy-Efficient Than Internal Combustion Vehicles

https://www.motortrend.com/news/evs-more-efficient-than-internal-combustion-engines/

And even the EPA make the same mistake - an EV can be potentially 100% efficient despite losing 10% in charging the battery!

https://www.fueleconomy.gov/feg/atv-ev.shtml#:~:text=An%20EV%20electric%20drive%20system,All%2DElectric%20Vehicles%20for%20details.

I wonder if these are basic maths errors (it is journalism so not that unlikely) or a deliberate attempt to mislead?

Obviously the recovered percentages are as a proportion of the amount of energy providing propulsion.

The energy efficiency case for EVs over fossil fuel are undeniable so it would seem pretty silly to attempt obvious FUD which will just be jumped upon by opponents who will attempt to use it to discredit the whole concept.

JKenH

michaels said:

JKenH said:

JKenH said:

I am amused by some of the calculations adopted by some organisations to push the efficiencies of EVs. In this particular example 10% of the energy is lost in charging, another 18% in the drivetrain , 3% in power train and cooling and 0-4% in auxiliary electric use. Regeneration then recovers 22% leaving a net loss of 9-13%. 

Losses incurred in charging are lost forever as are drivetrain, powertrain and electrical losses. Regeneration cannot recover these losses. Those 31-35%losses are gone forever. Neither can regeneration recover losses due to rolling resistance or drag. Regeneration can only convert kinetic energy back into electricity, i.e. recharging the battery by deceleration or by converting the kinetic energy acquired descending a hill and to acquire that kinetic energy you have either had to use the battery to get the car up to speed or to the top of a hill. 

Electric Vehicles Are Way, Way More Energy-Efficient Than Internal Combustion Vehicles

https://www.motortrend.com/news/evs-more-efficient-than-internal-combustion-engines/

And even the EPA make the same mistake - an EV can be potentially 100% efficient despite losing 10% in charging the battery!

https://www.fueleconomy.gov/feg/atv-ev.shtml#:~:text=An%20EV%20electric%20drive%20system,All%2DElectric%20Vehicles%20for%20details.

I wonder if these are basic maths errors (it is journalism so not that unlikely) or a deliberate attempt to mislead?

Obviously the recovered percentages are as a proportion of the amount of energy providing propulsion.

The energy efficiency case for EVs over fossil fuel are undeniable so it would seem pretty silly to attempt obvious FUD which will just be jumped upon by opponents who will attempt to use it to discredit the whole concept.

I suspect it is a mistake but this is the EPA website.This is the header at the top of the web page. The other image was from a journalistic source.

Coastalwatch

thevilla said:

In the last few months this thread has become a fossil fuel promotion. I'm out!  Bye.

Haven't visited this thread for months, just popped back to see if it there was anything of interest. Seems not. Like @thevilla will be doing, I shall simply continue giving it a wide berth.

Petriix

thevilla said:

In the last few months this thread has become a fossil fuel promotion. I'm out!  Bye.

I find if you just ignore certain posters then there's a fair amount of good quality information in the thread. It's also mildly helpful to be kept abreast of the latest FUD, especially when properly referenced counter-arguments are forthcoming from the better informed contributors. 

Martyn1981

michaels said:

JKenH said:

JKenH said:

I am amused by some of the calculations adopted by some organisations to push the efficiencies of EVs. In this particular example 10% of the energy is lost in charging, another 18% in the drivetrain , 3% in power train and cooling and 0-4% in auxiliary electric use. Regeneration then recovers 22% leaving a net loss of 9-13%. 

Losses incurred in charging are lost forever as are drivetrain, powertrain and electrical losses. Regeneration cannot recover these losses. Those 31-35%losses are gone forever. Neither can regeneration recover losses due to rolling resistance or drag. Regeneration can only convert kinetic energy back into electricity, i.e. recharging the battery by deceleration or by converting the kinetic energy acquired descending a hill and to acquire that kinetic energy you have either had to use the battery to get the car up to speed or to the top of a hill. 

Electric Vehicles Are Way, Way More Energy-Efficient Than Internal Combustion Vehicles

https://www.motortrend.com/news/evs-more-efficient-than-internal-combustion-engines/

And even the EPA make the same mistake - an EV can be potentially 100% efficient despite losing 10% in charging the battery!

https://www.fueleconomy.gov/feg/atv-ev.shtml#:~:text=An%20EV%20electric%20drive%20system,All%2DElectric%20Vehicles%20for%20details.

I wonder if these are basic maths errors (it is journalism so not that unlikely) or a deliberate attempt to mislead?

Obviously the recovered percentages are as a proportion of the amount of energy providing propulsion.

The energy efficiency case for EVs over fossil fuel are undeniable so it would seem pretty silly to attempt obvious FUD which will just be jumped upon by opponents who will attempt to use it to discredit the whole concept.

Can I ask what your concern is? Maybe I'm being stupid, but all of the charts explain how much energy is put to the road. They aren't about efficiency, when driving, which is where over unity and exceeding 100% would be an issue.

So, with regen, in an extreme situation of acceleration, brake, acceleration, brake, you can of course put more energy to the road, even more than equal to the original 100% in the battery, since you are re-using the same energy.

For instance, let's imagine an extreme situation, with a BEV with a small battery. So the battery has 100% energy when you start driving. You then accelerate to 30mph, and drive a short distance. This has resulted in 14% of the battery energy being put to the road. 4% has gone as distance travelled, and the remaining 10% is kinetic energy in the vehicle travelling at 30mph. Now, the lights ahead go red, you just can't make it through, and regen to a stop, at say 40% efficiency (just an example figure), so of that 10% energy, 4% goes back into the batts.

The battery is now down to 90%. And of you pop again, quickly reach 30mph and drive a short distance, but have to stop at a roundabout. Same figures again, 14% (of the original 100%) is put to the road, taking you down to 76%, but regen takes you back to 80%. [At this point cumulatively you've put 28% to the road, but crucially, you've gotten 8% back.]

On we go, with pedestrian lights, someone turning right, but having to wait for a gap, a T junction, another roundabout, zebra crossing and so on.

After 7 of these examples, we've put 98% of the original energy to the road, but have 30% remaining in our battery.

I appreciate this is a very silly example, but the point is, whilst the efficiency of this trip is very low, and we won't get great mileage from our full battery, the point has always been to compare the energy put to the road - and a BEV (also a HEV and PHEV*) can actually re-use (regeneration) some of the energy more than once, whereas an ICE converts the kinetic energy into heat and brake wear, when it has to stop quickly.

Hope this makes sense, and please don't worry too much about the specific numbers. I appreciate the upper limits  may look like a trick, but it simply reflects the additional benefits of an EV over an ICE, when stop and go driving is involved.

*This will of course depend on the size of the motor and battery, since smaller units won't be able to manage peak loads as high as a BEV (typically), but gentle regen will help.

JKenH

Two stories from Electrek. Tesla last week cut prices significantly in the U.S. and in Europe and China. The cuts were as much as 20% to Model Y prices to bring it under the IRA threshold for the $7,500 tax rebate. (If you qualify, a new Model Y is now $20k cheaper. This has had the desired effect on demand. What does it do though for customer sentiment and used prices? 

I haven’t heard about any UK price cuts. Would current Tesla owners like to see prices cut in the UK or left where they are?

Tesla (TSLA) is seeing ‘unprecedented demand,’ stores hitting new records

Tesla (TSLA) is currently experiencing “unprecedented demand” in the US following the significant price cuts that happened last week.

https://electrek.co/2023/01/17/tesla-tsla-unprecedented-demand-stores-hitting-new-records/

Amid demand concerns, Tesla cuts prices by up to $13K in US

Tesla has massively cut prices across new models in the US (update: and Europe), with the largest price drop occurring on the Model Y, which is now $13K and 20% cheaper than it was yesterday.

Below are the new and old prices for Tesla’s various models in the US. Similar price drops happened in Europe, though you’ll have to look country-to-country for those.

Model	Old price	New price	Difference
Model 3	$46,990	$43,990	-$3K (-6%)
Model 3 Performance	$62,990	$53,990	-$9K (-14%)
Model Y	$65,990	$52,990	-$13K (-20%)
Model Y Performance	$69,990	$56,990	-$13K (-19%)
Model S	$104,990	$94,990	-$10K (-10%)
Model S Plaid	$135,990	$114,990	-$21K (-15%)
Model X	$120,990	$109,990	-$11K (-9%)
Model X Plaid	$138,990	$119,990	-$19K (-14%)

https://electrek.co/2023/01/12/amid-demand-concerns-tesla-cuts-prices-by-up-to-13k-in-us/

Edit: see post from Mart a bit further on. These articles are from 2023. No idea why they came up when I went on the Electrek website. Please ignore. apologies to all. 

michaels

Martin.  I understand your argument but don't think it gives a very useful way to look at efficiency which is traditionally measured as useful power output over total power input.

Martyn1981

michaels said:

Martin.  I understand your argument but don't think it gives a very useful way to look at efficiency which is traditionally measured as useful power output over total power input.

Glad you understood it, as it does seem odd.

Yep, if you want to compare efficiency, then that's where a rough 75% v's 20% figure for BEV v's ICE kicks in, but for energy to the road driving, especially trips involving stop and go periods, then it gets more complicated.

[Edit - Sorry, let me clarify, some charts just have the lower numbers, whilst some have broad ranges with higher numbers for BEV's (and HFCV's), but typically clarify that this is due to regen. M.]

And of course I'm not suggesting over unity, just like heatpumps can be claimed (poorly) to be about 300% efficient in the UK, when of course that's not true, and I even recall a fun short piece in New Scientist addressing this.