[voldar]

http://www.caranddriver.com/reviews/2017-chevrolet-bolt-ev-test-review

There is more to the Bolt than we know. Those 190 miles at 75 mph are great numbers IMHO.

 

[SSonnentag]

I agree. I'm very pleased with that number, and using a web-based calculator, I have come up with the following estimated ranges based on various speeds. Can't wait to get my Bolt!

55 mph - 247 miles
60 mph - 238 miles
65 mph - 227 miles
70 mph - 205 miles
75 mph - 190 miles
80 mph - 177 miles

 

[Bacardi]

Should be noted that the HVAC was set at 72f so you'd imagine it would get more if off...

 

[rmay635703]

Should be noted that the HVAC was set at 72f so you'd imagine it would get more if off...

More but by how much, at 75 I would expect 22kw going down the pipe, may only be an 8 mile difference.

 

[gpsman]

The data below is inconsistent with the laws of physics. It will be really interesting how far off those guesses are when they hit the streets.

Force (power) to push a car through air goes up with the cube of velocity. To go twice the speed requires 8 times the power.

I have come up with the following estimated ranges based on various speeds.

55 mph - 247 miles
60 mph - 238 miles
65 mph - 227 miles
70 mph - 205 miles
75 mph - 190 miles
80 mph - 177 miles

 

[Barry]

Useful information, and impressive it has that much range at 75 mph. Whenever I travel those distances, it is on interstate freeways, so the 238 figure means less to me. Now to really make it interesting, what is the range in frigid temps or rain or snow? You really have to know the minimum range to know if it will work for you. Those are the days you least want to be stranded.

 

[Bacardi]

Useful information, and impressive it has that much range at 75 mph. Whenever I travel those distances, it is on interstate freeways, so the 238 figure means less to me. Now to really make it interesting, what is the range in frigid temps or rain or snow? You really have to know the minimum range to know if it will work for you. Those are the days you least want to be stranded.

So many factors...What temp outside, what temp HVAC, how hard you accelerate/brake, amount of passenger/cargo weight, how fast you drive and how heavy is the rain...

 

[Steverino]

Now to really make it interesting, what is the range in frigid temps or rain or snow? You really have to know the minimum range to know if it will work for you. Those are the days you least want to be stranded.

Being a Volt owner, I have learned how far the 40 miles of range can take on on my daily commute: just about 40 miles, lol. Of course, what it also shows me is that an extra 30 miles would cover 99.999% of my normal commutes and trips. So I am very comfortable with the Bolt's 238 mile range, even after taking a winter cold hit. I think of the Bolt as an 70 mile range Volt, with a 270 mile "range extender" should I need to go further.

 

[ItsNotAboutTheMoney]

The data below is inconsistent with the laws of physics. It will be really interesting how far off those guesses are when they hit the streets.

Force (power) to push a car through air goes up with the cube of velocity. To go twice the speed requires 8 times the power.

However, time fish 1/velocity, so work increases as the square of distance.
And the other key component in the required power is rolling resistance, which only increases linearly with speed.

 

[Neromanceres]

The data below is inconsistent with the laws of physics. It will be really interesting how far off those guesses are when they hit the streets.

Force (power) to push a car through air goes up with the cube of velocity. To go twice the speed requires 8 times the power.

You would only be correct if Drag was the only force acting upon the car (which it clearly isn't). There are many other losses to be considered many of which do not apply in the same fashion. Drag while important is very much so overstated as a loss on EV forums.

 

[BAZINGA]

Useful information, and impressive it has that much range at 75 mph. Whenever I travel those distances, it is on interstate freeways, so the 238 figure means less to me. Now to really make it interesting, what is the range in frigid temps or rain or snow? You really have to know the minimum range to know if it will work for you. Those are the days you least want to be stranded.

You can use 7 years of Volt's being in service to glean a pretty good guess as to what the "BOTTOM" number might be. Based on my experience owning/operating 3 Volt's as my DD since March 2012 with a worse case day of minus 16 degrees and the car sitting out all day where temps never got higher than MINUS single digits my 2013 Volt with an EPA rating of 38 miles allowed me to drive 25 miles before the battery was exhausted and the ICE took over. Of course I experienced ERDTT during that 25 miles. Hard to know how that impacted my numbers and of course the Bolt can't do that.


My guess for a WORSE CASE scenario would be a real world range of about 140 miles. But since Bolts will be in the hands of individual owners this winter we should get some immediate feedback.

 

[Norton]

...Force (power) to push a car through air goes up with the cube of velocity. ....

Wrong. Square of velocity.

...And the other key component in the required power is rolling resistance, which only increases linearly with speed.

Correct.

... Drag while important is very much so overstated as a loss on EV forums.

Wrong. It's the main thing that power goes to at cruise speed with EV's, gassers, planes, bicycles, etc.

And this climate control 'Set to 72 deg' issue only matters when the outside ambient temp is different than 72 deg.

Car magazines need some engineering tech writer help when they get into reviewing EV's.....

 

[Neromanceres]

Wrong. It's the main thing that power goes to at cruise speed with EV's, gassers, planes, bicycles, etc.

And this climate control 'Set to 72 deg' issue only matters when the outside ambient temp is different than 72 deg.

Car magazines need some engineering tech writer help when they get into reviewing EV's.....

On your first point I disagree.
Drag is nearly negligible in an automobile below 50mph. Obviously the faster you go the more it becomes a factor but you need to hit pretty high speeds for it to become the majority factor.

In a plane drag is an obvious factor simply because of higher speeds and the fact that many of the control surfaces utilize drag to control the plane.

In a bicycle you are also correct simply because the other losses are so low. Rolling resistance is low. Direct chain drive is very efficient. And the powertrain is the human.

In an EV you have battery discharge losses, inverter losses, motor losses, wire/cable/connection losses, transmission losses (yes a single gear reduction still has losses), differential losses, joint and suspension losses, wheel hub losses and accessory overhead losses. Not to mention rolling resistance. While some of these losses are somewhat small they all add up to be a fair bit in the end.

Without taking drag (or charging losses) into consideration the average EV at lower speeds would be approximately 70-75% efficient.

On your last point I fully agree. Without knowing the outside conditions it's hard to tell if having the climate set to 72F would be a significant factor.

 

[Norton]

On your first point I disagree.
Drag is nearly negligible in an automobile below 50mph. ...

In an EV you have battery discharge losses, inverter losses, motor losses, wire/cable/connection losses, transmission losses (yes a single gear reduction still has losses), differential losses, joint and suspension losses, wheel hub losses and accessory overhead losses. Not to mention rolling resistance. While some of these losses are somewhat small they all add up to be a fair bit in the end.

Without taking drag (or charging losses) into consideration the average EV at lower speeds would be approximately 70-75% efficient.
......

Sorry, I disagree again.
50 mph is NO magic number. Aerodynamic drag is always there and it's related to Air Speed, not indicated MPH. And it increases with the square of velocity, so 49 mph is just slightly less drag than 50.
Try pedaling a bike at 30 mph.

I have read that EV's use the battery power at 90-95% efficiency. And the only waste is heat coming from various components in the system.
I don't have time to find references, anybody?

When you look at the rear of an EV while driving with an IR camera you don't see much of anything.
You know what you see coming from the rear of a gasser?
~75% wasted energy in the form of heat.

(You got me curious. After my commute home today I'll pop the hood of my Spark EV and point a cheapy IR temp reader at various components, including tires and hubs.)

 

[bxd20]

My worst case numbers are similar to Bazingas. If it's extremely frigid, and I travel at fast highway speeds, I get 40% off the EPA figure in my Volt.

238 - 40% = 143 miles. I am hopeful that is the absolute worst case for the continental US northern states, driving 75-78mph. My in laws live 62 miles away and there's no charging at that end, so we should be good.

Sometimes we drive CLE to TOR, which is 300 miles. This means we should be able to get 1/2 way and stop. Only problem now is the lack of any DCFC between the end points. If they installed them at the service centers along the NY Thruway (90) that would be ideal.

 

[Neromanceres]

Sorry, I disagree again.
50 mph is NO magic number. Aerodynamic drag is always there and it's related to Air Speed, not indicated MPH. And it increases with the square of velocity, so 49 mph is just slightly less drag than 50.
Try pedaling a bike at 30 mph.

I have read that EV's use the battery power at 90-95% efficiency. And the only waste is heat coming from various components in the system.
I don't have time to find references, anybody?

When you look at the rear of an EV while driving with an IR camera you don't see much of anything.
You know what you see coming from the rear of a gasser?
~75% wasted energy in the form of heat.

(You got me curious. After my commute home today I'll pop the hood of my Spark EV and point a cheapy IR temp reader at various components, including tires and hubs.)

I never claimed that 50mph is a "magic number" it's simply an approximate value that changes from vehicle to vehicle depending on circumstances. And yes drag force is always present it's just not statistically significant at lower speeds (for a car).

As for losses you are way off base. Nothing as mechanically complex as a car will have an overall efficiency of 90 to 95%. Battery discharge losses alone are nearly 5%. Inverter losses are not constant but approach 5 to 10%. The electric motor will have losses that also vary based on power, load and motor speed but will vary from 3 to 10%. And then mechanical losses in the single gear reduction, differential, wheel hubs etc.. will account for another 10 to 15%.

In a gas powered car the automatic transmission alone has mechanical losses that account for 20% of vehicle losses. And I'm fully aware that the average thermodynamic efficiency of an ICE (alone) is about 25%. That doesn't even take into account all the other losses in a "gasser"

 

[stuart22]

This Drag discussion..... has me wondering: how significant would the range difference be between driving 75mph at an altitude of 5000' vs. driving 75mph at sea level, both at similar ambient temperatures?

 

[Norton]

Too true !
It's called Density Altitude and Pressure Altitude, heat and humidity all factor into it.
https://www.faasafety.gov/files/gsl...P-8740-02 DensityAltitude[hi-res] branded.pdf

Aero drag is much less at 5000'. This why jet aircraft can't fly 520 mph at low altitudes.
And EV's do not lose power with altitude compared to a non-turbo gassers.
An EV is fastest on the Moon where there is no aero drag.

 

[bxd20]

45mph in an ICE used to be magical in a sense. For the better part of 30 years, that's the speed that most automatic transmissions shifted into their highest gear. Thus dropping RPMs and maximizing fuel economy. So it was more efficient to drive 45mph than 40mph, if that meant the difference between 3rd and 4th gear in something like a W-body Impala. Now with 8 to 10 speed automatics coming out, the gear steps are so finely separated, that driving the slowest speed possible while in the highest gear possible is not a guarantee of maximizing fuel efficiency; in fact it's unlikely due to drag at those speeds.

 

[Norton]

...As for losses you are way off base. Nothing as mechanically complex as a car will have an overall efficiency of 90 to 95%. Battery discharge losses alone are nearly 5%. Inverter losses are not constant but approach 5 to 10%. The electric motor will have losses that also vary based on power, load and motor speed but will vary from 3 to 10%. And then mechanical losses in the single gear reduction, differential, wheel hubs etc.. will account for another 10 to 15%.
...."

All the record setting EV geeks used ~25mph for there 'feat'. Why?

As for your efficiency claims,, do you have references?

Mechanical losses that high? Really?
For one thing the differential is just along for the ride unless you are turning the wheel sharply.

So if I use ~10 kWh on my commute home, my transaxle, hubs and tires have heated up the equivalent of having a ~1500 watt hair dryer blasting them for an hour? I realize they would be air cooled while driving. So on a rolling dyno with no air flow?

We both need to find some scientific studies on EV efficiencies.