Range not close to as advertised

[SpaceEVDriver]

This is simply not true. The two biggest range killers in an EV are acceleration rate and speed. Always have been.
Limiting both will allow anyone to exceed the EPA rating.

Exactly. I regularly get 2.5 miles/kWh on the freeway and can easily reach 4-5 miles/kWh around town with stops, traffic, etc. When I decide to floor it, I get <2 miles/kWh. When I can stay at 35 mph in town for long distances, I can get up to 8 miles/kWh (1000 miles range).

Physics supports this too, obviously.

Work is the energy expended to move an object.
Work (energy) = Force * distance.
Force = mass * acceleration.

Work = mass * acceleration * distance.

Compare acceleration at 0.25 g over a km to acceleration at 1 g over that same km. Assume wind resistance is negligible:

W1 = m * 0.25 * 1 km
W2 = m * 1.0 * 1 km

W1/W2 = (m * 0.25 * 1) / (m * 1.0 * 1 )
mass is the same so m/m = 1.
W1/W2 = 0.25.

It costs 25% of the energy to accelerate at 0.25g compared with accelerating at 1g over the same distance. To put it another way, it costs 4x the energy to accelerate at 1g vs 0.25g for the same distance. Hard acceleration means more work, which means more energy expended to move the vehicle.

People often get confused because of the common claim that mass doesn’t really matter for range. What is often not included in that statement is that mass doesn’t matter much when velocity is constant. But velocity is *never* constant. And especially when in traffic and driving around town.


Slow down.
Ease off on accelerations.
Try to keep a constant speed whenever possible and you’ll see much better range numbers.

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[RickLightning]

Wow, a bunch of "I don't like to have a smile on my face" people...

A former neighbor didn't understand EVs much, nor did he care to. But, as he was above to move out of state, and get a very, very, very big salary (7 digits), he asked me about EVs and said "I might buy a Tesla". I explained to him how in his business, and with his presence (big guy), a Lightning would be more appropriate, and more useful to his family. I also told him about always having a smile when you get out, and offered him a ride sometime.

That afternoon he messaged me that he was free, and we went for a ride. At the corner of the development, I told him to grab the handle and lean back. He laughed, having no clue. Since he has a massive neck, I wasn't worried about whiplash. I cut the wheel right, stomped on the pedal, and as we accelerated, the rear tires lost traction around 20mph and squealed.

From the passenger seat, I hear a repeated "F*&k, F*&k, F*&k". I looked over and saw an ear to ear grin. I said "now do you get it?" and he laughed and said yes.

My lifetime mpk is either 1.8 or 1.9, I'd have to go look. I rarely drive more than 75, but I love the acceleration, so...

 

[RickKeen]

Accelerating slower also reduces your average speed. And most importantly, the amount of time you spend at the peak speeds where the V-squared air-drag factor kills your efficiency.
For example, if you accelerate in 5 seconds to 60 MPH and then drive 60 seconds to the next stoplight and brake hard, stopping within 10 seconds.
Compare to slowly accelerating to over 15 or 20 seconds to 60 MPH, cruising at 60 MPH for 40 seconds, then decel over 20 seconds, you have spent somewhat less time at 60 MPH (not sure if those made-up numbers integrate to the exact same distance, but illustrates the point).

Note that air-resistance at high speeds is energy lost regardless if you are accelerating, coasting, or decelerating. Coasting is not free (but it might be more efficient than using heavy regen).

Additionally as pointed out, regen is not perfectly efficient. You don't get all the energy back from decelerating the mass. And at higher accelerations and brakings, a higher percentage of heat loss is generated.

 

[K6CCC]

Now I know that some folks just can’t come to grips with changing the terrible way they are used to driving . But an EV is the only car that will reward that change in behavior with big gains in efficiency and dividends in savings. The change of mindset leads to a new kind of driving satisfaction that far exceeds making lots of noise and blowing a lots black smoke and generally stupid, rude and mindless driving.

The "HyperMilers" years ago demonstrated what CAN be achieved. Granted that was with ICE cars, but the concepts are the similar for an EV. However in a real world situation, most people HATE to have any of those HyperMilers on the same piece of road that they are driving because they have a horrible impact on traffic flow. That and obviously time has no value to them. I have watched people spend several blocks getting to 30 mph (with a 35 -45 mph speed limit) and then several more blocks slowing back down from 30 to stopped. Meanwhile everyone around them is having to lane change to get around them.

 

[HOTAS]

Extreme Hypermiling involves exploiting momentum with extreme speed fluctuations.
Reasonable, efficient EV driving techniques exploit momentum and declines (hills) to maintain speed and minimize noticeable speed changes, with a ”0 energy“ state on the power guage.
I drive this truck at less than ⅓ the fuel cost to drive an equivalent gas F150. Then Consider basically 0 maintenance costs (no oil changes, tuneups, brake jobs or service) and its significantly less overall cost than that. Love this truck.

 

[Henry Ford]

This is simply not true. The two biggest range killers in an EV are acceleration rate and speed. Always have been.
Limiting both will allow anyone to exceed the EPA rating .
And any notion that regen on the backend somehow balances rapid acceleration on the front end is false also.
Regen is a terribly inefficient recapture of unnecessarily used energy.
When stopping or slowing are necessary and unavoidable, regen is a Fantastic feature, but it’s much more efficient to have never
used the energy to begin with.
If everyone would limit their initial acceleration rate to no more than ’bottom of the Lightning bolt’ on the power guage, and begin to tapper back as the truck gains speeds, then consciously exploit “0 power” Glides as much as possible, you would all exceed the EPA rating.
And of course limit your highway/interstate speed to no more than 70mph (or less, is better) and Inflating your tire to at least 40psi.

Now I know that some folks just can’t come to grips with changing the terrible way they are used to driving . But an EV is the only car that will reward that change in behavior with big gains in efficiency and dividends in savings. The change of mindset leads to a new kind of driving satisfaction that far exceeds making lots of noise and blowing a lots black smoke and generally stupid, rude and mindless driving.

I was talking specifically about acceleration in the real world. If more energy is required to accelerate quickly to the same speed, where does the extra energy go. I suppose there could be a little friction loss if you break traction and maybe a tiny amount of heat loss but these aren't meaningful losses which is why I used the qualifier "little to no." If there is some other energy loss please fill me in.

 

[Henry Ford]

Exactly. I regularly get 2.5 miles/kWh on the freeway and can easily reach 4-5 miles/kWh around town with stops, traffic, etc. When I decide to floor it, I get <2 miles/kWh. When I can stay at 35 mph in town for long distances, I can get up to 8 miles/kWh (1000 miles range).

Physics supports this too, obviously.

Work is the energy expended to move an object.
Work (energy) = Force * distance.
Force = mass * acceleration.

Work = mass * acceleration * distance.

Compare acceleration at 0.25 g over a km to acceleration at 1 g over that same km. Assume wind resistance is negligible:

W1 = m * 0.25 * 1 km
W2 = m * 1.0 * 1 km

W1/W2 = (m * 0.25 * 1) / (m * 1.0 * 1 )
mass is the same so m/m = 1.
W1/W2 = 0.25.

It costs 25% of the energy to accelerate at 0.25g compared with accelerating at 1g over the same distance. To put it another way, it costs 4x the energy to accelerate at 1g vs 0.25g for the same distance. Hard acceleration means more work, which means more energy expended to move the vehicle.

People often get confused because of the common claim that mass doesn’t really matter for range. What is often not included in that statement is that mass doesn’t matter much when velocity is constant. But velocity is *never* constant. And especially when in traffic and driving around town.


Slow down.
Ease off on accelerations.
Try to keep a constant speed whenever possible and you’ll see much better range numbers.

You "proved" your point by demonstrating a faster vehicle is less efficient. Accelerating at 1g for 1km puts you at like 300mph. Not useful information. Do the math to a reasonable speed instead of a distance and report back your findings.

To be clear, we are all in agreement speed kills efficiency. What seems to be in dispute is that acceleration hurts efficiency in any meaningful way. I'm not saying is zero, but it's so close to zero as to not factor in real world driving.

 

[RickKeen]

To be clear, we are all in agreement speed kills efficiency. What seems to be in dispute is that acceleration hurts efficiency in any meaningful way. I'm not saying is zero, but it's so close to zero as to not factor in real world driving.

Disagree for multiple reasons:
1. Electric motors do not have their max efficiency at max power. This difference can be as much as 20%-30% from the peak efficiency point.
2. Batteries do not have their max efficiency when being discharged (or charged) at max power. Hardly a "non factor"
(1 &2) also apply to regen.
3. Battery state of charge can dramatically impact efficiency during regen. A 90% charged battery will not charge (regen) efficiently.
4. Battery and motor temps can impact efficiency. There is a peak temp that they both work at their most efficient. Too hot and battery efficiency goes down as does the motors.
5. Whenever the cooling system has to work to actively remove heat, you are losing efficiency (as compared to only needing air cooling). Aggressive driving that causes the cooling compressor and fan to kick in will burn more juice.
6. With more aggressive driving, you run the risk of accidentally or necessarily using the friction brakes more often.

And speed and acceleration are inter-related. We all agree that higher speeds mean less efficiency. When you accelerate quicker, you spend more of your time and distance at higher speeds. Not so much an issue on the freeway, but for stoplight to stoplight driving on an urban road, this will be more than a "non-factor".

 

[inchman254]

I would add:

Mountains uphill = < 1 KW/mi (for non flat lander trucks)

I just happened to do a test this morning. In a continuous climb (no ups and downs on the way) I lost 18 km (11 miles) per 1000 ft of elevation. [Range at bottom minus range at top minus distance travelled]. That works out to about 4. 5kWh or 3.5% in an ER. To keep it simple, since we all drive differently, 20 km/10 miles/5kWh per 1000 ft.

Of course, if there are up and downs, you don't get as much back on the downs as you spend on the ups.

 

[Firn]

Exactly. I regularly get 2.5 miles/kWh on the freeway and can easily reach 4-5 miles/kWh around town with stops, traffic, etc. When I decide to floor it, I get <2 miles/kWh. When I can stay at 35 mph in town for long distances, I can get up to 8 miles/kWh (1000 miles range).

Physics supports this too, obviously.

Work is the energy expended to move an object.
Work (energy) = Force * distance.
Force = mass * acceleration.

Work = mass * acceleration * distance.

Compare acceleration at 0.25 g over a km to acceleration at 1 g over that same km. Assume wind resistance is negligible:

W1 = m * 0.25 * 1 km
W2 = m * 1.0 * 1 km

W1/W2 = (m * 0.25 * 1) / (m * 1.0 * 1 )
mass is the same so m/m = 1.
W1/W2 = 0.25.

It costs 25% of the energy to accelerate at 0.25g compared with accelerating at 1g over the same distance. To put it another way, it costs 4x the energy to accelerate at 1g vs 0.25g for the same distance. Hard acceleration means more work, which means more energy expended to move the vehicle.

People often get confused because of the common claim that mass doesn’t really matter for range. What is often not included in that statement is that mass doesn’t matter much when velocity is constant. But velocity is *never* constant. And especially when in traffic and driving around town.


Slow down.
Ease off on accelerations.
Try to keep a constant speed whenever possible and you’ll see much better range numbers.

That isnt quite the same though.

Its not acceleration for a certain distance, that would have different speeds.
Its also not acceleration for a certain time, that would also have different speeds.

Accelerate at 4m/s^2 for 10 seconds and you are going 40m/s, or about 90mph. But to achieve the same 90mph you would accelerate at 2m/s^2 for 20 seconds, or 8m/s^2 for 5. In driving we typically achieve the same speed, its how fast, and how long, we accelerate to get there.

 

[RickLightning]

I just happened to do a test this morning. In a continuous climb (no ups and downs on the way) I lost 18 km (11 miles) per 1000 ft of elevation. [Range at bottom minus range at top minus distance travelled]. That works out to about 4. 5kWh or 3.5% in an ER. To keep it simple, since we all drive differently, 20 km/10 miles/5kWh per 1000 ft.

Of course, if there are up and downs, you don't get as much back on the downs as you spend on the ups.

Using the GOM is useless. The right way to do that is with an OBD reader and CarScanner. You would know the exact kWh used.

 

[RickLightning]

One of the realities is that efficiency is heavily dictated by topography and climate. On the Mach-E forum, a bunch of owners reported very high efficiencies while many of us struggled to, reach 3.0. The common factor for most of them was flat roads (think Florida) and warm temps.

We have driven to/from Florida probably a half dozen times with the Mach-E, and each time noticed our efficiency on This Trip (reset each charging stop) climbing as we approach Florida. In Florida, cruising at 73 to 75mph, I might see low 3.Xs. Here in Michigan, I never see 3.0. People think where they live is flat, and it isn't. Except Florida, Arizona, Kansas, ...

 

[inchman254]

Using the GOM is useless. The right way to do that is with an OBD reader and CarScanner. You would know the exact kWh used.

Carscanner would tell me the total kWh used but that would include the kWh used to travel the horizontal distance, too. My calc was just for the kWh cost for the elevation change.

 

[Henry Ford]

Disagree for multiple reasons:
1. Electric motors do not have their max efficiency at max power. This difference can be as much as 20%-30% from the peak efficiency point.
2. Batteries do not have their max efficiency when being discharged (or charged) at max power. Hardly a "non factor"
(1 &2) also apply to regen.
3. Battery state of charge can dramatically impact efficiency during regen. A 90% charged battery will not charge (regen) efficiently.
4. Battery and motor temps can impact efficiency. There is a peak temp that they both work at their most efficient. Too hot and battery efficiency goes down as does the motors.
5. Whenever the cooling system has to work to actively remove heat, you are losing efficiency (as compared to only needing air cooling). Aggressive driving that causes the cooling compressor and fan to kick in will burn more juice.
6. With more aggressive driving, you run the risk of accidentally or necessarily using the friction brakes more often.

And speed and acceleration are inter-related. We all agree that higher speeds mean less efficiency. When you accelerate quicker, you spend more of your time and distance at higher speeds. Not so much an issue on the freeway, but for stoplight to stoplight driving on an urban road, this will be more than a "non-factor".

I'm not talking about regen, aggressive driving, using friction brakes, or driving faster. I'm making a simple point. Accelerating quickly has little impact on REAL WORLD driving efficiency.

There's a misconception that rapid acceleration in an EV has significant affect on efficiency. This is probably a relic of gas engines which need to run richer to accelerate quicker. Most of the excess fuel is turned into heat out the exhaust. This is obviously very inefficient. EVs might create a little bit more heat under hard acceleration but it's not on the same scale as ICE vehicles. Again, I'm talking about real world driving. Not race course driving. Or going faster. Or factoring in regen...

 

[K6CCC]

People think where they live is flat, and it isn't. Except Florida, Arizona, Kansas, ...

Arizona is NOT flat.

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