Scouting for Petrol........................

[kzb]

Erm... I now think the energy required to go distance D at speed v is proportional to v^2.

So it takes four times the kWh to travel distance D at a speed of 2v compared to just v.  

Not double, as I said before, but four times.

An EV that gets 4 miles/kWh at 35mph would get just 1 mile/kWh at 70mph (considering air resistance only).

 

[markyh]

52 minutes ago, kzb said:

Erm... I now think the energy required to go distance D at speed v is proportional to v^2.

So it takes four times the kWh to travel distance D at a speed of 2v compared to just v.  

Not double, as I said before, but four times.

An EV that gets 4 miles/kWh at 35mph would get just 1 mile/kWh at 70mph (considering air resistance only).

 

Your average efficiency EV, in summer (18-30 degrees) will do 4-5 miles kwh at 35 mph easily. An efficient one (Tesla ,  KIA, Hyundai) 6-7 m/kwh.  But there is no way it drops 4 x @ 70mph. So something is up. I would expect 2-3 miles per kwh @ 70 from an efficient EV, 1.5 to 2 m/kwh from a normal one. To drop to 1 mile kwh you need to be doing something like 100mph. 

[Frugal Git]

8 hours ago, Gigantic Purple Slug said:

Doesn't matter what fuel, just get any fuel.

Today I discovered my car was a lot more fuel economic if it is driven at 55 mph. In fact stupidly so. I was a bit amazed at the number of people tanking along hell for leather on the motorway though.

All the stations on the motorway or dual carriageways were out of fuel. Did seem to be fewer lorries on the road than normal.

yeah I was surprised how fast people were driving to petrol stations 🤦‍♀️

Since buying my Model S - and it's a stupid one with ludicrous mode .... I drive every long journey at 56 mph all the way, drafting lorries 😂 Gets up to 56mph In about 2.6 seconds so that bits is a laugh.

It's amazing even over a 70 mile journey how little difference it makes in reality to the overall journey time, especially in perception. The annoying part is *always* city traffic and you quickly realise it doesn't make any difference how fast you get to that point. If it's busy in the city, you'll get frustrated either way and the few extra minutes saved on the motorway at 70mph+ would quickly be forgotten.

Doing it this way I can beat the official rated range, provided that it's reasonably warm and not raining (amazing the difference that makes too with an EV).

The stupid thing is in my case it doesn't even matter financially as it has free supercharging for life. Nearly up to 9000 miles now for a total of £45 in charging costs (I'm starting to pay occasionally to use a slow charger near work now, at 20p kWh for a top up it's ok). But I enjoy driving it. Sit there with music on, all good 

Cheap motoring. At this rate, the savings will cover a new battery. And even if that makes it a wash, it's a pleasure to drive and has a permanent free internet connection that I can just sit there and watch YouTube/Netflix whenever I need to get some peace out of the house. 'just going to charge for an hour'.

Bliss.

Edited September 28, 2021 by Frugal Git

[Frugal Git]

7 hours ago, Riedquat said:

Moving very slowly is very inefficient too (take the extreme case of the engine running and the car not moving). Somewhere between 40 mph and 60 mph seems to be the sweet spot for most petrol cars. The efficient revs band for a petrol engine is pretty narrow too, which is why cars have gears. EVs have much less low speed wastage, to the point where I doubt that stop-start traffic is particularly bad for them, at least if it's not cold enough to need to run the heater full blast.

Oh believe me, slow speed stop start in an EV makes a big difference to range too. Starting and stopping a 2.5 ton car isn't great.

The other day I ended up doing 3 miles in 1h and 15 mins (having done the previous 68 miles in about the same).

My wh/mi chart went through the roof in those last three miles. it was infuriating 😂

[Frugal Git]

1 hour ago, markyh said:

Your average efficiency EV, in summer (18-30 degrees) will do 4-5 miles kwh at 35 mph easily. An efficient one (Tesla ,  KIA, Hyundai) 6-7 m/kwh.  But there is no way it drops 4 x @ 70mph. So something is up. I would expect 2-3 miles per kwh @ 70 from an efficient EV, 1.5 to 2 m/kwh from a normal one. To drop to 1 mile kwh you need to be doing something like 100mph. 

Yeah there are many other factors that affect things in reality - rolling resistance etc I expect. In isolation the equations @kzbquoted probably hold. I am not going to pretend to be an expert and I didn't sleep so not enough time to look at the physics.

From observation though, the other day I was doing about 40mph for a while, and it was doing around 200 wh/mi. At 80 mph it's doing over 420 wh/mi iirc, so nowhere near 800. This is on 21" alloys though, which are pretty crap for economy.

Edited September 28, 2021 by Frugal Git

[A.steve]

9 hours ago, shlomo said:

You are just being sarcastic nothing in the ground has changed, except the queues will naturally subside 

Being sarcastic, yes... "just being sarcastic"  - no.  I am, at least, also being pedantic. I'd like to think I've been wryly amusing and witty...  but not Chris - of course... This post is not admission of disingenuous promotion of malicious propaganda.

I've never been concerned about what is in the ground.  Which parties control access to resources, of course, is a different matter. I am concerned by political acts - especially those that result in changes to hard-won legislation that protected principles that are important to civil society.  I am especially concerned when these changes arise in the context of a manufactured crisis... which is exploited to avoid the usual scrutiny - i.e. the legal and political conventions on which (in Britain) everyone's rights depend.  I am not very concerned by potential problems with the natural world. I am very concerned by the conduct of authority figures that have great influence over all our experiences.

I noticed the fuel queues did subside "naturally" on Sunday.  That happened when fuel stations stopped selling fuel. It is now obvious that following government advice (that 'panic buying' was not necessary) was seriously deleterious to one's personal interests.  With the track record that is being established... one has to wonder:  in future, will anyone rational follow any future government advice?  From my perspective, it is looking more and more like a dependable contrarian indicator.  When will the tipping point be reached, when the government can only influence the bulk of the public by feigning demands for the diametric opposite of what they actually want?

~ Would you find it helpful if I were to punctuate my sarcasm ⸮

 

[kzb]

1 hour ago, markyh said:

Your average efficiency EV, in summer (18-30 degrees) will do 4-5 miles kwh at 35 mph easily. An efficient one (Tesla ,  KIA, Hyundai) 6-7 m/kwh.  But there is no way it drops 4 x @ 70mph. So something is up. I would expect 2-3 miles per kwh @ 70 from an efficient EV, 1.5 to 2 m/kwh from a normal one. To drop to 1 mile kwh you need to be doing something like 100mph. 

There are other things going on in addition to air resistance.   In addition to air resistance there is rolling resistance, which I did not consider.

The rolling resistance is generally said to be a lot smaller than air resistance at high speed, but 35mph isn't very fast so it could make a significant difference to the economy curve.  It will be a greater proportion of the total resistance at low speed.  Your figures are roughly 3X greater energy per mile at 70 than at 35mph, and I think that fits with this explanation quite well.

EVs are heavy.  I imagine the tyre pressures have to be quite high because of this, but even so the rolling resistance could be higher than an equivalent ICE vehicle, basically because of the greater weight.

[smash]

38 minutes ago, Frugal Git said:

yeah I was surprised how fast people were driving to petrol stations 🤦‍♀️

Since buying my Model S - and it's a stupid one with ludicrous mode .... I drive every long journey at 56 mph all the way, drafting lorries 😂 Gets up to 56mph In about 2.6 seconds so that bits is a laugh.

It's amazing even over a 70 mile journey how little difference it makes in reality to the overall journey time, especially in perception. The annoying part is *always* city traffic and you quickly realise it doesn't make any difference how fast you get to that point. If it's busy in the city, you'll get frustrated either way and the few extra minutes saved on the motorway at 70mph+ would quickly be forgotten.

Doing it this way I can beat the official rated range, provided that it's reasonably warm and not raining (amazing the difference that makes too with an EV).

The stupid thing is in my case it doesn't even matter financially as it has free supercharging for life. Nearly up to 9000 miles now for a total of £45 in charging costs (I'm starting to pay occasionally to use a slow charger near work now, at 20p kWh for a top up it's ok). But I enjoy driving it. Sit there with music on, all good 

Cheap motoring. At this rate, the savings will cover a new battery. And even if that makes it a wash, it's a pleasure to drive and has a permanent free internet connection that I can just sit there and watch YouTube/Netflix whenever I need to get some peace out of the house. 'just going to charge for an hour'.

Bliss.

its funny isn't it that people want to needlessly make their lives stressful by expecting to be able to go brakeneck speed everywhere when like everyone knows if you are starting or terminating in an inner city area all that accelerating and then heavy braking (stress) doesnt shorten your journey time in any significant way at all. I could drive from Portsmouth to West London and it would take longer to go through Putney high street and Fulham Palace road than the whole journey up the A3. I find the same frustration with motorists when I'm city cycling; its like oh so important to overtake the cyclist and slam on the brakes at the half an hour to clear queue of cars. Meanwhile guy on the bike is in the pub.....

Quite honestly, I just find it all plain weird.

[kzb]

18 minutes ago, Frugal Git said:

Yeah there are many other factors that affect things in reality - rolling resistance etc I expect. In isolation the equations @kzbquoted probably hold. I am not going to pretend to be an expert and I didn't sleep so not enough time to look at the physics.

From observation though, the other day I was doing about 40mph for a while, and it was doing around 200 wh/mi. At 80 mph it's doing over 420 wh/mi iirc, so nowhere near 800. This is on 21" alloys though, which are pretty crap for economy.

I think I finally got it right.

Energy = Force x Distance

The "force" is air resistance, which is proportional to speed squared.  Therefore the air resistance force will be X4 for X2 the increase in speed.  The distance is the same so the energy must be 4X.

I think we need to be careful about generalising from one poorly controlled experiment.  Ancillary equipment will take a bigger percentage of your energy at low speed than at high speed.  The wind direction and strength could change.  Only a tiny change in the gradient of the road makes a massive difference to the energy needed per mile.  If your tyres are underinflated the rolling resistance could be unexpectedly high.  So lots of potential explanations.

[Confusion of VIs]

4 hours ago, kzb said:

Yes I'd agree with all that.

I had a Fiesta Ecoboost hire car a couple of years ago, it wouldn't take 6th gear under about 65mph.

EVs don't suffer as much with slow driving.  On the other hand there is no hiding the fact you need power to go fast.  An EV still requires four times the power to go twice as fast, just like any other surface vehicle operating in the atmosphere.  It will get about half the miles/kWh figure at 70mph as it does at 35mph.

(Note yes I know there is rolling resistance as well as air resistance, which does not follow the power 2 relationship with speed, so it won't be exactly half.)

Overcoming air resistance requires 8 times the power to double the speed.

In real life rolling resistance is a large factor at normal speeds so the reality is rather better than that. This is the graph for my car. I presume the large temp effect is down to running the heating for hours on end at the lower speeds.

Over 200m at 100mph should be enough for most people.

    

[Confusion of VIs]

14 minutes ago, kzb said:

I think I finally got it right.

Energy = Force x Distance

The "force" is air resistance, which is proportional to speed squared.  Therefore the air resistance force will be X4 for X2 the increase in speed.  The distance is the same so the energy must be 4X.

 

The distance travelled per s also doubles so 4 x 2 = 8

[kzb]

14 minutes ago, Confusion of VIs said:

The distance travelled per s also doubles so 4 x 2 = 8

The instantaneous power for double the speed is 8X, but you complete the distance in half the time.  So the energy to complete that distance at double speed is 8/2 = 4.

[kzb]

28 minutes ago, Confusion of VIs said:

I presume the large temp effect is down to running the heating for hours on end at the lower speeds.

Air density increases as the temperature decreases, so the air resistance decreases as the temperature rises.

Rolling resistance is higher when the tyres are cold, even if the pressure is kept equal.   It's because the material is less elastic.

Is there not some bad effect on the battery at low temperature as well?

Edited September 28, 2021 by kzb

[shlomo]

9 hours ago, A.steve said:

Being sarcastic, yes... "just being sarcastic"  - no.  I am, at least, also being pedantic. I'd like to think I've been wryly amusing and witty...  but not Chris - of course... This post is not admission of disingenuous promotion of malicious propaganda.

I've never been concerned about what is in the ground.  Which parties control access to resources, of course, is a different matter. I am concerned by political acts - especially those that result in changes to hard-won legislation that protected principles that are important to civil society.  I am especially concerned when these changes arise in the context of a manufactured crisis... which is exploited to avoid the usual scrutiny - i.e. the legal and political conventions on which (in Britain) everyone's rights depend.  I am not very concerned by potential problems with the natural world. I am very concerned by the conduct of authority figures that have great influence over all our experiences.

I noticed the fuel queues did subside "naturally" on Sunday.  That happened when fuel stations stopped selling fuel. It is now obvious that following government advice (that 'panic buying' was not necessary) was seriously deleterious to one's personal interests.  With the track record that is being established... one has to wonder:  in future, will anyone rational follow any future government advice?  From my perspective, it is looking more and more like a dependable contrarian indicator.  When will the tipping point be reached, when the government can only influence the bulk of the public by feigning demands for the diametric opposite of what they actually want?

~ Would you find it helpful if I were to punctuate my sarcasm ⸮

 

You really are too intelligent for this forum...

 

[Casual-observer]

So as it turns out the emergency visas are more required in the DVLA for cheap admin workers to replace the communists who have been pretending to work from home for over a year inside the DVLA

The life and times of a public sector key worker eh 

[markyh]

10 hours ago, kzb said:

Air density increases as the temperature decreases, so the air resistance decreases as the temperature rises.

Rolling resistance is higher when the tyres are cold, even if the pressure is kept equal.   It's because the material is less elastic.

Is there not some bad effect on the battery at low temperature as well?

Did a measured 50mph run today, 36.3 miles, used 9.4kwh in the 2014 EV. So 3.86m/kwh. I would have seen well over 4, maybe 5 if i had done the whole journey @ 35mph. 

[Gigantic Purple Slug]

Why pay £25 for the Joshua fight on Sky when you can watch the petrol station punch ups for free on the Daily Rage.

Seen a couple of great haymakers this morning.

[shlomo]

28 minutes ago, Gigantic Purple Slug said:

Why pay £25 for the Joshua fight on Sky when you can watch the petrol station punch ups for free on the Daily Rage.

Seen a couple of great haymakers this morning.

So have I, we humans are so crazy 

[Confusion of VIs]

12 hours ago, kzb said:

The instantaneous power for double the speed is 8X, but you complete the distance in half the time.  So the energy to complete that distance at double speed is 8/2 = 4.

Sorry I just skimmed the discussion and thought you were talking about power.

11 hours ago, kzb said:

Air density increases as the temperature decreases, so the air resistance decreases as the temperature rises.

Rolling resistance is higher when the tyres are cold, even if the pressure is kept equal.   It's because the material is less elastic.

Is there not some bad effect on the battery at low temperature as well?

The first two will have some effect but i think pretty marginal. 

I haven't noticed any battery effect, I think that effects countries with colder climates than the UK.

Running the heating can take up to 4kw, if you  are driving at 40ish for 8hrs this itself could knock off 160m (32kwh @ 5m per kwh). Newer 3 & Y models have a heat pump that reduces this loss by over two thirds) 

[shlomo]

https://www.manchestereveningnews.co.uk/news/greater-manchester-news/i-no-choice-stranded-driver-21684919?fbclid=IwAR1jlAm59tWSUGfOBVCTf8xsrZa9buC-kJz5bq_0idEqd6JyRgnyyklnee0

I had no choice": Stranded driver, 30, down to last few miles of fuel slept in car overnight near to Oldham petrol station

[winkie]

 

[shlomo]

https://news.sky.com/story/fuel-supply-crisis-live-prices-at-highest-level-in-eight-years-as-boris-johnson-under-pressure-to-prioritise-key-workers-at-pumps-12419438

Fuel supply crisis live: Petrol stations 'could face disruption for up to a month'; 27% of stations without fuel but situation improving

Army drafted in to drive fuel tankers this week; Boris Johnson suggests key workers won't get priority at petrol stations; drivers facing disruption for "up to a month"; 27% of petrol stations out of fuel.

[markyh]

6 minutes ago, shlomo said:

https://news.sky.com/story/fuel-supply-crisis-live-prices-at-highest-level-in-eight-years-as-boris-johnson-under-pressure-to-prioritise-key-workers-at-pumps-12419438

Fuel supply crisis live: Petrol stations 'could face disruption for up to a month'; 27% of stations without fuel but situation improving

Army drafted in to drive fuel tankers this week; Boris Johnson suggests key workers won't get priority at petrol stations; drivers facing disruption for "up to a month"; 27% of petrol stations out of fuel.

EV heaven, our replacement short term Peugeot E-208 GT arrives next Tuesday to take over from the returning 2018 Nissan Leaf Tekna 40kw, at the end of its lease this Friday. Then the Tesla model 3 LR arrives to replace the E-208 sometime in November.  Volt came back from the dealers today after a software update so we are all rocking on 99% EV again as a family. 

I just don't do queueing with the plebs, especially 50 cars deep for 3-4 hrs. 

[A.steve]

1 hour ago, shlomo said:

You really are too intelligent for this forum...

That requires double 'snark-marks' - LOL!

I checked out themindsjournal.com... but didn't find it my cuppa... despite the advertisement seeking to entice me with an image of attractive venetian blinds.  I am interested in psychology... and have read around the subject. Some material is fascinating - and some is dark. Promoted "popular" stuff is mostly vacuous.  Carl Jung's work (founded on study of schizophrenia) - for example - is mind-bogglingly bizarre, fairly inaccessible - but laced with staggering broad insights which, I feel, are presented as if they are obvious throw-away observations.  I quickly loose interest if/when focus shifts to superficial frivolities... when a whiff of horoscopes wafts in on the breeze.

I first looked at HPC when I was frustrated that it seemed impossible (for anyone) to earn as quickly as house prices appeared to rise... around 2005/2006.  My personal research, at that time, had been dramatically narrower than it is today.  I wanted there to be a fair relationship between earnings and title to residential property - like the bulk of people drawn to the site... but that wasn't what kept my attention. I have an affinity for HPC because it attracts a remarkably broad range of people... with wildly differing experiences and expertise... and... some have, at least, a passing interest in economics, finance, banking, politics and the interaction of these lofty domains with everyday experiential reality.  I solved 'get a house' for myself in 2018... but I come back to HPC because the ideas that drew me in the first place were much broader than how one person can buy one home.  The situation that our (probably global) regime has created does affect mental health. The implications of unaffordable unsuitable and insecure accommodation definitely has a profound influence on almost every aspect of everyone's life - irrespective individual affluence - whether people realise this, or not.

For many years, I've actively looked for other forums (both real life and online) to pursue my interests. I have not been very successful.  I discovered Positive Money - but stepped back after dreaming that it had been conceived during an illicit tryst between Momentum and the kindergarten division of Extinction Rebellion. My improvised comedy instructor reckoned that one should just start one's own organizations... and retain control. Unlike being appropriately daft (which quickly becomes second nature) restructuring civilization to provide the society with which I want to engage... is proving more challenging.

If anyone pictured me with a white cat, feeding my shiver of laser-augmented sharks: Neither the pretend plague, nor the fuel farce, are collateral damage arising from any of my experiments.

 

[shlomo]

34 minutes ago, A.steve said:

That requires double 'snark-marks' - LOL!

I checked out themindsjournal.com... but didn't find it my cuppa... despite the advertisement seeking to entice me with an image of attractive venetian blinds.  I am interested in psychology... and have read around the subject. Some material is fascinating - and some is dark. Promoted "popular" stuff is mostly vacuous.  Carl Jung's work (founded on study of schizophrenia) - for example - is mind-bogglingly bizarre, fairly inaccessible - but laced with staggering broad insights which, I feel, are presented as if they are obvious throw-away observations.  I quickly loose interest if/when focus shifts to superficial frivolities... when a whiff of horoscopes wafts in on the breeze.

I first looked at HPC when I was frustrated that it seemed impossible (for anyone) to earn as quickly as house prices appeared to rise... around 2005/2006.  My personal research, at that time, had been dramatically narrower than it is today.  I wanted there to be a fair relationship between earnings and title to residential property - like the bulk of people drawn to the site... but that wasn't what kept my attention. I have an affinity for HPC because it attracts a remarkably broad range of people... with wildly differing experiences and expertise... and... some have, at least, a passing interest in economics, finance, banking, politics and the interaction of these lofty domains with everyday experiential reality.  I solved 'get a house' for myself in 2018... but I come back to HPC because the ideas that drew me in the first place were much broader than how one person can buy one home.  The situation that our (probably global) regime has created does affect mental health. The implications of unaffordable unsuitable and insecure accommodation definitely has a profound influence on almost every aspect of everyone's life - irrespective individual affluence - whether people realise this, or not.

For many years, I've actively looked for other forums (both real life and online) to pursue my interests. I have not been very successful.  I discovered Positive Money - but stepped back after dreaming that it had been conceived during an illicit tryst between Momentum and the kindergarten division of Extinction Rebellion. My improvised comedy instructor reckoned that one should just start one's own organizations... and retain control. Unlike being appropriately daft (which quickly becomes second nature) restructuring civilization to provide the society with which I want to engage... is proving more challenging.

If anyone pictured me with a white cat, feeding my shiver of laser-augmented sharks: Neither the pretend plague, nor the fuel farce, are collateral damage arising from any of my experiments.

 

You are mad and feel at home in the company of other mad people 

How to say it with fewer words..