Should EVs have efficiency standards?

[JBee]

The solar is not really that relevant to the title of the thread and should really go in one of the solar threads, but here it goes anyways.
(I'll do the calcs in metric and convert and I've used my CAD model for accurate dimensions of the CT parts)

First I'd like to adjust the assumptions a bit. In regards to weight, given the size of the battery bank and that there is no hill that can be driven up that also doesn't produce a fairly similar regen or coast range when driving down it, meaning vehicle mass can largely be neglected in range calculations, bar the extra rolling resistance losses caused by mass, which can add up.
Based on the following dimensions:

• CT Frontal Area: 25sqft (2.65sqm including exposed tyre area)
• Aero Cd: 0.30
• Rolling Crr: 0.01
• Battery/ESC/Motor eff: 0.85
• Drivetrain eff: 0.95
• Air Density: 1.225kg/m³

calculations look something like this:

• 10MPH/16kmh = total W 1141W of which 44W is aero and 1097W is rolling = 114Wh/mile or 71Wh/km
• 40MPH/64kmh = total W 7159W of which 2771W is aero and 4388W is rolling = 179Wh/mile or 112Wh/km
  
• 65MPH/105kmh = total W 19017W of which 11890W is aero and 7126W is rolling = 293Wh/mile or 181Wh/km

It's clear that highway speeds will consume more power. If the CT is the same weight as a F150 supercrew (2506kg) it's also the same as a MX (2487kg) with a 100kWh battery. If we assume that battery costs will reduce by its release date, we can fairly reliably assume that at least a 100kWh pack will come with a DM AWD as well. Given that a AWD Model X also has a similar drivetrain as the AWD CT, and the same weight we can pretty much neglect those differences in our assumptions. That largely leaves us with aero, wheels and clearance.
I'm assuming that the CT weight can be maintained at that level due to the extra rigidtiy of SS in comparison to Aluminium, and and together with optimsed manufacturing will result in a longer vehicle, with similar cab space but longer external area and bed than a MX.

Given the MX has a range of 330miles, and the CT DM 300miles, we should expect a about a 10% increase from the extra CT aero component if the above is comparable.

Using MX Frontal Area: 24sqft (2.31sqm)
MX Cd: 0.24

we get:

• 10MPH/16kmh = MX 1126W or 1% less than CT
• 40MPH/64kmh = MX 6325W or 13% less than CT
• 65MPH/105kmh = MX15455 or 23% less than CT

So here it looks like we are about 13% short of batteries to achieve the 300mile range for the DM CT using a 100kWh pack.

Then we can compare it to the 15mile solar option. This one has more variables, in particular in regards to PV type, season and location etc. and the actual size of the PV n the CT. Using a better grade PV cell shouldn't really increase the price much as it is only a small area.
(BTW I used Dallas and NREL SAM to model the PV outputs below, which are based only daily average 6.76kWh/sqm/day)

Lets at least assume a premium PV (LG - 20W/sqft)) and range at 330Wh/mile with the following dimensions from CAD CT:

Rear Roof Glass Area: 20sft (1.85sqm) = LG 398W = 8miles range (GaAs 498W )
Vault Cover Area: 31sqft (2.85sqm) = LG 614W = 13miles range (GaAs 767W)
Remaining rear area: 11sqft (1sqm) = LG 215W 5 miles range (GaAs 269W)
Total rear roof area of CT: 61sqft (5.7sqm) = LG 1227W 26 miles of range (GaAs 1534W)

If EM's "off the cuff" remark was accurate within 10-20%, or maybe they've already modeled the solar option and he was quoting that, then the vault cover area at 13 miles of range using LG PV cells would actually be feasible at that consumption rate. Especially so if he added the rear roof window area as well or went GaAs. Technically the whole area could be used for about 26miles of extra range.

Ah yeah, I also assumed MPPT and 1 axis tracking of the PV using CT air suspension and about 30degrees of vehicle movement for orientation using "Solar Summon" to follow the sun. You just need a triangular parking spot pointing south...

Based on the above my prediction is that the CT will have a 120kWh pack for the DM AWD version to achieve that range and hover around the 350-370Wh/mile mark. The TM will be a 200kWh pack, and the SM a 100kWh. All with the latest battery type at around $100/kWh, so from the top, $20k, $12k and $10k for the packs. This is the largest single item cost of a EV.

 

[juliusa]

Because you don’t load up an electric car with ground up solar panels. Using the electricity generated from the panels in no way reduces the amount that can be produced going forward.

If you want something analogous to the solar panels, that would be the gasoline refinery, which does, in fact, have a cost for building, a set lifetime during which it generates the fuel, and then another cost for demolition. It also adds another yet another cost for generation.

Exactly.

Less electricity used for EVs, less solar panels (wind turbines, gas turbines, coal plants, nuke plants, whatever), less environmental cost, less societal cost.
Less gasoline used for cars, less refineries, less environmental cost, less societal cost.

Less is more when it comes to energy consumption.

 

[richtrav]

Ah yeah, I also assumed MPPT and 1 axis tracking of the PV using CT air suspension and about 30degrees of vehicle movement for orientation using "Solar Summon" to follow the sun. You just need a triangular parking spot pointing south...

My idea would be an arc-shaped parking space going from roughly a 7 o'clock to 11 o'clock position, depending, and you just have the car slowly inch through the space during the day as if it were making a verrrrryyyy slow right turn. The air suspension could be adjusted according to the season and latitude.

Based on the above my prediction is that the CT will have a 120kWh pack for the DM AWD version to achieve that range and hover around the 350-370Wh/mile mark. The TM will be a 200kWh pack, and the SM a 100kWh. All with the latest battery type at around $100/kWh, so from the top, $20k, $12k and $10k for the packs. This is the largest single item cost of a EV.

Those numbers sound about right, my guess was that the Wh/mi would be higher than the heaviest Model X which is rated at 350 Wh/mi. The tri-motor model should have a lower Wh/mi rating due to the heavier battery.

 

[JBee]

Official Tesla MX quoted range is 307wh/mile for the LR and 333Wh/mile for the HP.

I'd imagine 350Wh/mile is real use for the MX?

If so and we apply the same factor to the CT we get about 400Wh/mile which still works with the pack sizes above. These are the usable part of the packs btw as I'd think Tesla is adding extra capacity to that anyway for them to "unlock" after once the packs have been tested on us consumers to be ok.

Interestingly the cross sectional profile of the CT is only 14% more than the MX, but the Cd is also 25% worse.
Further the effect of speed on range is profound, much more pronounced than on a ICE due to the high EV efficiency.
If you want to tow, or go further just go 50mph/80kmh instead of 65mph to add 30% range.

Technically you could go as long as the sun shines each day at 10mph just with the whole rear roof covered in PV on the CT and no batteries... Better than being stranded, and more than three times as fast as walking.

 

[Cyber_Dav]

Technically you could go as long as the sun shines each day at 10mph just with the whole rear roof covered in PV on the CT and no batteries... Better than being stranded, and more than three times as fast as walking.

If Elon is correct and you can add 15 miles in an 8 hour day, that is less than 2 miles per hour. Only during daylight and only going north. Tonneau must face southerly for maximum sun exposure. Anything else equals vastly reduced solar charging.

 

[JBee]

The 15 mile range is at highway speeds 65MPH which has greater consumption than at 10MPH where aero uses nothing. Also I said whole rear roof covered with PV.
The Sun is in the east in the morning and west in the evening, so driving going east to west in a arc that goes over the south, that takes all day, with some reversing in the arvo would be best. The point was to demonstrate that you can go a lot further than 15miles if you had to, if you also go slower, because you were stranded in the outback without a way to charge it. Call it a "limp home mode" using PV.

 

[Cyber_Dav]

The 15 mile range is at highway speeds 65MPH

First I've heard that. Do you have a reference?

 

[JBee]

Well theres no point in quoting a 10MPH range...What speed is implied in the ranges given on the Tesla website for the CT?

Regardless, the point remains you can go much further than 15miles if you travel slower, which uses less energy per mile.

 

[MarcusMaximus]

Exactly.

Less electricity used for EVs, less solar panels (wind turbines, gas turbines, coal plants, nuke plants, whatever), less environmental cost, less societal cost.
Less gasoline used for cars, less refineries, less environmental cost, less societal cost.

Less is more when it comes to energy consumption.

*sigh* Ok, if you want to play it that way, then at least set any such regulations at similar levels for both, taking into account the lowest range of possible sources for both. Something like 1mpge for EV’s seems reasonable, to match current mpg requirements and account for 100% solar(this is likely enormously rounding up, but that’s ok).

 

[juliusa]

*sigh* Ok, if you want to play it that way, then at least set any such regulations at similar levels for both, taking into account the lowest range of possible sources for both. Something like 1mpge for EV’s seems reasonable, to match current mpg requirements and account for 100% solar(this is likely enormously rounding up, but that’s ok).

One has nothing to do with the other. If there are ICE standards, there should be EV standards - ever increasing efficiency.

My view is there should be no efficiency standards - for ICE or EVs.

 

[JBee]

How is MPGe standards relevant to the thread title regarding aerodynamics?

 

[MarcusMaximus]

One has nothing to do with the other. If there are ICE standards, there should be EV standards - ever increasing efficiency.

My view is there should be no efficiency standards - for ICE or EVs.

Sure, and they should be equivalent in terms of social and energy cost, since the whole goal is to lower those, yes? It doesn’t make much sense to have MUCH higher standards for one form than you do for another, unless your intent is to Boise the latter. So, establish one standard overall level of pollution acceptable in trade for the ability to have time efficient transportation, and stick to it, regardless of that form of transportation.

You suggest 0mpg as that limit, I would suggest something like 60mpg(or, allowing for power by solar and rounding up, 1mpge).

 

[JBee]

@MarcusMaximus

Define "pollution".

 

[juliusa]

Sure, and they should be equivalent in terms of social and energy cost, since the whole goal is to lower those, yes?

I'm not in favor of any regulations, and unclear of the goals - someone said efficiency standards were to reduce dependence on foreign oil, so maybe they are just a leftover with no purpose?

If the goal is efficiency, then we should have regulations that increase efficiency for ICE and regulations that increase efficiency for EVs. No relationship between the two - increasing efficiency requirements over time. That is if you are a believer in government regulations.

If you buy in to the "relativity" argument, the current vehicle emission standards make no sense. With so many old cars on the road with poor fuel efficiency, the incremental reduction in emissions does not justify the increased cost.

So many reasons to get rid of the efficiency regulations....

How is MPGe standards relevant to the thread title regarding aerodynamics?

Better aerodynamics improves MPGe. It is one of the things ICE manufacturers work on to meet government fuel economy standards.

 

[MarcusMaximus]

@MarcusMaximus

Define "pollution".

The presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects.

 

[MarcusMaximus]

I'm not in favor of any regulations, and unclear of the goals - someone said efficiency standards were to reduce dependence on foreign oil, so maybe they are just a leftover with no purpose?

If the goal is efficiency, then we should have regulations that increase efficiency for ICE and regulations that increase efficiency for EVs. No relationship between the two - increasing efficiency requirements over time. That is if you are a believer in government regulations.

If you buy in to the "relativity" argument, the current vehicle emission standards make no sense. With so many old cars on the road with poor fuel efficiency, the incremental reduction in emissions does not justify the increased cost.

So many reasons to get rid of the efficiency regulations....

Better aerodynamics improves MPGe. It is one of the things ICE manufacturers work on to meet government fuel economy standards.

Pardon, why is there no relation between the two? They both spend energy, producing a societal/environmental cost, in order to increase time efficiency of transportation, at roughly the same rate. The goal of such regulations should be to increase the efficiency of such transportation. Otherwise, why not have a different regulation for every single make/model of vehicle?

 

[Daniel in SD]

This whole argument is ridiculous. Regulations are designed to solve problems. There is no need for efficiency regulation on EVs because more efficient EVs are cheaper to manufacture than less efficient ones. The battery is by far the expensive component so manufacturers are already doing everything they can to make EVs as efficient as possible.
Less efficient ICE vehicles are cheaper to manufacturer and the cost of a larger gas tank is trivial. A libertarian would say that consumers should be able to chose to purchase less efficient vehicles. That's a political question because practically speaking most people are horrible at taking into account long term costs. It harms the whole economy when people can't drive anywhere when gas prices spike.
Now, vampire drain regulation I could get behind!

 

[juliusa]

Pardon, why is there no relation between the two?

If you increase the efficiency of an EV, it lowers the amount of energy used and has all the benefits of lower energy consumption. This is true regardless of what goes on with the efficiency of ICE vehicles. Hence, no relationship.

 

[juliusa]

There is no need for efficiency regulation on EVs because more efficient EVs are cheaper to manufacture than less efficient ones. The battery is by far the expensive component so manufacturers are already doing everything they can to make EVs as efficient as possible.

Why is the MPGe for the Leaf and i3 so much less than the Model 3?

I'm against regulations on MPGe (and MPG), I just don't understand why people are in favor of them for ICE by not EV.

 

[MarcusMaximus]

If you increase the efficiency of an EV, it lowers the amount of energy used and has all the benefits of lower energy consumption. This is true regardless of what goes on with the efficiency of ICE vehicles. Hence, no relationship.

But why draw the line at EV vs ICE? Why not between gas vs diesel? Or trucks vs sedans? Or an F150 vs F250? Or...

You’re making a division that’s entirely arbitrary. The goal is to improve efficiency of transportation overall, not of one particular powertrain. So one consistent marker for efficiency would be the way to accomplish that goal, not different ones for every possible combination of parts in that transportation.

We could base that efficiency marker on current EV’s, to make them more efficient, but that would mean banning every ICE vehicle currently on the market or planned to ever be.