Chevy Bolt EV Forum banner
1 - 20 of 29 Posts

·
Registered
Joined
·
41 Posts
Discussion Starter · #1 · (Edited)
I was alarmed to see my Bolt consume excessive battery range (all figures based on middle LCD screen figure).

This was a 60 mi. trip that was 90% freeway driving on flat road with cruise control in 'L' mode used both times.

Driving to destination at 80 mph on cruise resulted in 80 mi. of battery consumption.

Driving back home at 65 mph on cruise resulted in 49 mi. of battery consumption.

I am shocked to see how dramatically only a 25% increase in speed (65 to 80 mph) caused 40% more power consumption (49 mi. E vs 80 mi. E)!


Would a multi-speed automatic instead of a 1-speed direct drive unit prevent major efficiency losses like this?
 

·
Registered
Joined
·
643 Posts
No this is a problem with all cars - both aero dynamic loads and HP requirement increase as a square/cube of speed - it is quite a bit more expensive to go 80 vs 65 (and illegal in the US except on a few roads) - and it’s way more expensive to go 65 vs. 40 mph...

After 40 mph the vast majority of incremental power required to maintain speed is to counter aero-dynamic drag which increases with a velocity-squared component in the equation - so it gets expensive energy wise very quickly

At 55 mph the Bolt can easily go over 320 miles on a charge...
 

·
Registered
Joined
·
390 Posts
This was a 60 mi. trip that was 90% freeway driving on flat road with cruise control in 'L' mode used both times.

Driving to destination at 80 mph on cruise resulted in 80 mi. of battery consumption.

Driving back home at 65 mph on cruise resulted in 49 mi. of battery consumption.
These numbers do not mean 40% more power consumption.

While driving, the car constantly re-estimates remaining range based on 'recent' efficiency. So, the 80 mi. of range 'lost' during the first half of the trip is partly due to actual energy consumption and partly due to the car re-estimating how far the remaining energy will take you. The 49 miles of lost range on the way back, would have been more if the car had not re-estimated how far the remaining energy would take you.
I am shocked to see how dramatically only a 25% increase in speed (65 to 80 mph) caused 40% more power consumption (49 mi. E vs 80 mi. E)!
Why? When going 25% faster, aero drag (which is the biggest of the energy consumers) is increased by 56% (1.25 * 1.25 = 1.56). So, an overal increase of consumption of 40% would not even seem so odd.

Would a multi-speed automatic instead of a 1-speed direct drive unit prevent major efficiency losses like this?
A very hypothetical question, but no. Speed kills range. Nothing in the world can change that.
 

·
Registered
Joined
·
390 Posts
...both aero dynamic loads and HP requirement increase as a square/cube of speed
Not as bad as it sounds, as the second is a consequence of the first. They don't double up.

it is quite a bit more expensive to go 80 vs 65 (and illegal in the US except on a few roads) - and it’s way more expensive to go 65 vs. 40 mph...
In relative terms, yes. In absolute terms, I think not really ;-)
 

·
Registered
Joined
·
643 Posts
what I still hate about all this is the "head wind" effect - which has tanked my range on more than one occasion even when I was 'being good' and driving responsibility - EV's still require a bit too much "paying attention" when trying to maximize long distance driving - and most people are un aware of the effects of external factors on their EV range - and are severely disappointed when the car does not meet their expectations…

witness the:

a) 2017/2018 winter range discussions for the Bolt forums
b) anyone who's set out with a plan to drive near the limit of the Bolt's range and found one or two minor external factors screw up their plans

EV's still take too much work - you can't just get in and drive them if you're trying to go some distance - we and the car industry still have a lot of work to do…
 

·
Registered
Joined
·
1,046 Posts
At 55 mph the Bolt can easily go over 320 miles on a charge...
In a mild climate....
At a constant 55 mph, not quite 320 miles. Unless the Bolt is at an altitude of around 7,000 feet. But there’s no flat road at 7,000 feet that goes for 320 miles.

One would need regeneration in order to achieve 320 miles. But then it’s not a constant 55 mph.

At Toronto elevation a constant 55 mph range is about 275.6 miles. With one skinny driver aboard, at 72°F ambient temperature, on a totally flat road, with no wind at all, and stock low rolling resistance tires.
 

·
Registered
Joined
·
643 Posts
I'll stand corrected by Cehjun- still far in excess of the stated 236 mile range…13.9% greater than the stated 236 mile range for example ;-)

speed is the range killer make no doubt.
 

·
Premium Member
Joined
·
2,385 Posts
I drove 313 miles nonstop at highway (55 mainly) speeds last summer. Still could have gone another 10 miles or so if I had stretched the battery all the way. There was an overall elevation drop of about 3,000 feet, so that helped the range some, but even if the entire drive was flat, I would have still easily cleared 300 miles.
 

·
Registered
Joined
·
7,024 Posts
what I still hate about all this is the "head wind" effect...
I find that paying attention to the trend indicator (the little "tongues" that go up or down on the left side of the battery level display) is useful to keep on top of this. When I see it doing something I don't expect I say "Hey Google .... what's the wind?" to see if I'm battling a headwind or not.
 

·
Registered
Joined
·
269 Posts
I was alarmed to see my Bolt consume excessive battery range (all figures based on middle LCD screen figure).

This was a 60 mi. trip that was 90% freeway driving on flat road with cruise control in 'L' mode used both times.

Driving to destination at 80 mph on cruise resulted in 80 mi. of battery consumption.

Driving back home at 65 mph on cruise resulted in 49 mi. of battery consumption.

I am shocked to see how dramatically only a 25% increase in speed (65 to 80 mph) caused 40% more power consumption (49 mi. E vs 80 mi. E)!


Would a multi-speed automatic instead of a 1-speed direct drive unit prevent major efficiency losses like this?
Know this is an older post, but using cruise control does not always relate to better efficiency. CC does not anticipate inclines or declines and wastes efficiency trying to maintain a constant speed. Most humans will slightly depress the accelerator to maintain uphill speed and then start letting up as you approach the summit. The CC will realize you are loosing speed on a hill then overpower to compensate the climb, wasting energy. Even the modern adaptive CC will over compensate. Which is why often you will see brake lights followed by a surge of speed. Like a 14 year old learning to drive..
 

·
Registered
Joined
·
2,952 Posts
using cruise control does not always relate to better efficiency
While probably true, I think CC is more efficient in the vast majority of conditions. Even with an ICE it is usually more efficient and an ICE has a built-in inefficiency of using a disproportionally higher amount of fuel for acceleration or maintaining speed on in incline, especially if it has to downshift to do so. So, without any real evidence, I suspect that CC is best with the Bolt nearly always. Unless you're going to be one of those annoying traffic cloggers that slows down 20 MPH just because you're going uphill, but that's just equivalent to slowing down in general.
 

·
Registered
Joined
·
10,126 Posts
Know this is an older post, but using cruise control does not always relate to better efficiency. CC does not anticipate inclines or declines and wastes efficiency trying to maintain a constant speed. Most humans will slightly depress the accelerator to maintain uphill speed and then start letting up as you approach the summit. The CC will realize you are loosing speed on a hill then overpower to compensate the climb, wasting energy. Even the modern adaptive CC will over compensate. Which is why often you will see brake lights followed by a surge of speed. Like a 14 year old learning to drive..
Not correct.. The CC on the Bolt does not overshoot or undershoot. It maintains your set speed to plus or minus 1 mph, far better than an ICE vehicle. It does a far better job of conserving energy than all but the most alert hypemiler.
 

·
Registered
2020 Bolt LT
Joined
·
362 Posts
... Even the modern adaptive CC will over compensate. Which is why often you will see brake lights followed by a surge of speed. Like a 14 year old learning to drive..
Can't speak for other ICE cars, but my previous car Honda civic 1.5l turbo with CVT had the best adaptive cruise. Our toll roads and Hwys in Texas have 80mph speed limit. The civic in Eco mode tamed the ACC's need to keep exact speed. It allowed it to dip 2-3 mph below the set speed on uphills but never went over set speed. And because of the CVT, never any jerking or shifting was noticed. Direct-injected + turbo engine = low RPM torque. @85mph set cruise control it was humming in a 2400 RPM range. I Loved that car! The bolt can drop -1 mph speed on the cruise control. I wish it would have a similar ECO mode.
 

·
Registered
Joined
·
269 Posts
Not correct.. The CC on the Bolt does not overshoot or undershoot. It maintains your set speed to plus or minus 1 mph, far better than an ICE vehicle. It does a far better job of conserving energy than all but the most alert hypemiler.
Still in the learning stage of my Bolt, so haven't got around to utilizing the CC.
But I have always been able out hyper mile the CC on all my ICE vehicles, adaptive or not.
Since the Bolt provides instant torque, I can see it maintaining set speed without drama. Also, since fuel usage is no longer a factor, an extra KW or two is no big thing.
Being new to the EV scene, I still have a bit of gas station avoidance guilt.😐
 

·
Registered
Joined
·
10,126 Posts
Still in the learning stage of my Bolt, so haven't got around to utilizing the CC.
But I have always been able out hyper mile the CC on all my ICE vehicles, adaptive or not.
Since the Bolt provides instant torque, I can see it maintaining set speed without drama. Also, since fuel usage is no longer a factor, an extra KW or two is no big thing.
Being new to the EV scene, I still have a bit of gas station avoidance guilt.😐
Didn't mean to jump on you. This is just one of my hobbyhorses. The fact that an electric drivetrain can maintain the selected speed with great efficiency, and precision, while recouping more than half of the kinetic energy on downhills, makes it very challenging to beat by hypermiling. Say you want to go from point A to point B at 65 mph average. If you hypermile, you need to let the car coast downhill to recoup any of the kinetic energy, since you can't regen (unless it is a hybrid) You will not recoup 100% because you will inevitable go downhill faster than the average speed you are trying to maintain, and aero drag goes up exponentially. As you slow down after the decent you must match your throttle position exactly to your intended average speed. If you hit the throttle too soon, or too late, you are using extra energy.

Unless this is a hobby, the added stress from the attention required to match CC is not worth the percent or two you may gain, over CC. Never had adaptive CC so can't say for sure, but since the advantages of electric drive, and regen would still apply, I suspect the adaptive software would have to be pretty bad to not match a human for judging when to change speed.

As for fuel usage no long being a factor, you have it just backwards. Your Bolt is a hot hatch, with a two gallon fuel tank, and unless you live near a megalopolis, the fueling stations are rare, and often broken.
 

·
Registered
Joined
·
269 Posts
Didn't mean to jump on you. This is just one of my hobbyhorses. The fact that an electric drivetrain can maintain the selected speed with great efficiency, and precision, while recouping more than half of the kinetic energy on downhills, makes it very challenging to beat by hypermiling. Say you want to go from point A to point B at 65 mph average. If you hypermile, you need to let the car coast downhill to recoup any of the kinetic energy, since you can't regen (unless it is a hybrid) You will not recoup 100% because you will inevitable go downhill faster than the average speed you are trying to maintain, and aero drag goes up exponentially. As you slow down after the decent you must match your throttle position exactly to your intended average speed. If you hit the throttle too soon, or too late, you are using extra energy.

Unless this is a hobby, the added stress from the attention required to match CC is not worth the percent or two you may gain, over CC. Never had adaptive CC so can't say for sure, but since the advantages of electric drive, and regen would still apply, I suspect the adaptive software would have to be pretty bad to not match a human for judging when to change speed.

As for fuel usage no long being a factor, you have it just backwards. Your Bolt is a hot hatch, with a two gallon fuel tank, and unless you live near a megalopolis, the fueling stations are rare, and often broken.
Just took my first trip. A roundtrip 150 miler (2x75). First leg using headlights, defroster, some heat, heated steering wheel and one bar seat produced a sad 3.6 kwh avg. Coming back using some ac in the daylight averaged almost 5 kwh. Speed was 60-75 80% highway. No cruise control either way only because I haven't got there yet.
One thing I noticed that the trip seemed to fly by effortlessly. Some of which I credit the one pedal operation. Never touched the brake except to startup and shutoff.
Found the seat comfortable all the way. (2020 Premier).
Seeing gas up to $2.92 (Fl) sure helps justify my EV purchase.
 
1 - 20 of 29 Posts
Top