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Discussion Starter #1
Today, Chevrolet Program Engineering Manager Rob Mantinan said, "Sometimes driving slower gets you there faster." Meaning that driving slower extends your range and might possibly allow you to skip a charging stop.

How can I determine what the optimal speeds and charging stops are for a particular trip?
 

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How can I determine what the optimal speeds and charging stops are for a particular trip?
A Better Route Planner is one tool. An a energy assist tool in the Chevy app. When running the numbers, sometimes it's better to drive as fast as you can. The battery charges faster when at a lower level of charge. All depends on the spacing of the chargers.
 

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How significant can the time savings be on an 8-hour trip?
 

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Today, Chevrolet Program Engineering Manager Rob Mantinan said, "Sometimes driving slower gets you there faster." Meaning that driving slower extends your range and might possibly allow you to skip a charging stop.

How can I determine what the optimal speeds and charging stops are for a particular trip?
Technically, what Rob said is correct: "Sometimes." But you can find a corner case for anything. However, under normal and reasonable conditions, what he said is untrue. On long trips, driving makes up the lion's share of time, so a 10% reduction in time spent driving (i.e., driving faster) will outweigh a 20% to 30% reduction in time spent charging.

As an extreme example, Hyundai recently did a publicity stunt where they drove a couple of Hyundai Kona Electric's over 600 miles on a single battery charge, bringing their time spent charging down to zero. The only catch? It took them 35 hours of driving to do. By contrast, I could drive my Bolt EV 300 miles on a battery charge at 45 to 50 mph, stop and L2 charge up over night, and drive another 300 miles at 45 to 50 mph. When it's all said and done, I would have driven the same distance in half the time.
 

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Discussion Starter #7
So basically what I'm wondering is whether there is any possibility of time savings on a trip from Athens, GA to Danville, KY and vice versa. I have done that trip in about 9 hours, driving about 9 mph over the speed limit, and stopping at the EA stations in Kennesaw, Chattanooga, Knoxville and Willamsburg. Could I possibly save any time overall by driving slower and/or stopping at slower chargers? What if I do the trip through South and North Carolina, stopping at the EA stations in Commerce, Greenville, and Asheville instead of Kennesaw and Chattanooga?
 

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So basically what I'm wondering is whether there is any possibility of time savings on a trip from Athens, GA to Danville, KY and vice versa. I have done that trip in about 9 hours, driving about 9 mph over the speed limit, and stopping at the EA stations in Kennesaw, Chattanooga, Knoxville and Willamsburg. Could I possibly save any time overall by driving slower and/or stopping at slower chargers? What if I do the trip through South and North Carolina, stopping at the EA stations in Commerce, Greenville, and Asheville instead of Kennesaw and Chattanooga?
I suppose it depends, but that seems like an awfully long time to complete that trip. It should be less than 7 hours driving time when going the speed limit, and it's less than 400 miles, meaning the Bolt EV should need two 30 to 40 minute charging sessions at most to complete the drive.
 

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ABRP shows the trip is 355 miles, 8 hours and 15 minutes including 2 charging stops, 26 minutes and 23 minutes.
 

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I did a while ago some math for 500e.
Turned out it is better for me to drive faster on highway speed (70 mph) than going via city/suburbs 50 mph.
However, that applied to WINTER condition. I did not take charging into consideration. It was only due to the fact the cabin heater must pump energy into the car. So going faster I use more energy per minute, but over time and energy spent is more when driving slower.
 

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I did the math once based on a questionable chart that plotted energy consumption at various speeds, and concluded 75 MPH was the optimal speed, but that assumed charging locations exactly where you needed them...

I'd say if you will be close to being able to skip a charging session, then slowing down will probably overall be faster, but if you can't skip a charging session, just drive faster.

*all of this is theoretical since I don't own an EV. Newscoulomb is experienced in this regard.
 

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I'd say if you will be close to being able to skip a charging session, then slowing down will probably overall be faster, but if you can't skip a charging session, just drive faster.
This is a good summary, and generally true in my experience. Today, we only have a sparse network of chargers. I am able to get anywhere I want to go using DCFCs, but that is not the case for everyone. And I often have to hit certain chargers to make it. In those cases, driving faster (but not so fast that I cannot make it) actually saves times.

It's a moot point for me, since I drive at the posted speed limit anyway. But I don't begrudge those who want to drive faster; that's what the left lane is for. (I do begrudge those who want to drive faster but refuse to pass and just tailgate instead).
 

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(I do begrudge those who want to drive faster but refuse to pass and just tailgate instead).
How many times I had to go to the left lane for them to pass me... :D
 

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I understand where the idea comes from, but in "normal" conditions, driving the speed limit and adding charge stops is generally going to get you there faster.

I recently did a 236 mile each way trip in the CO Rockies. The return trip was done without a charge stop and I arrived home with 7% SOC, 4.8 miles/kWh.

The primary factor than enabled me to get such a high MPK was the typical weekend traffic returning to Denver. From Silverthorn, you climb up to ~11K feet elevation at the Eisenhower tunnel, then it is all downhill to Denver, roughly 5000-6000 feet elevation drop, averaging about 30MPH with traffic. My range entering the tunnel was 58, and reached 110 when it got to the Denver metro area. I regenerated about 3-4kWh on that 40 mile stretch, enough to get me home at 55-65 MPH.

Had this leg not been congested (rare on weekends), I surely would have needed a stop somewhere in the Denver area, and that might have been a 15-20 minute stop. But, I probably would have cut 30-45 minutes on the trip due to the higher speeds.
 

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Discussion Starter #16
I suppose it depends, but that seems like an awfully long time to complete that trip. It should be less than 7 hours driving time when going the speed limit, and it's less than 400 miles, meaning the Bolt EV should need two 30 to 40 minute charging sessions at most to complete the drive.
Oops, I didn't mean just driving time, I meant total trip time including a meal and charging sessions. But maybe I have been making one too many charging stops. I've been making 3 stops per trip. Being risk averse, I pay more attention to the lower number on the GOM than to the middle one. I sure would hate to run out of juice. Decades ago I ran out of gas on the interstate and the experience cured me of that sort of stupidity.

Now I'm wondering about staying off the interstate in Georgia and going up US 441 where there are no EA chargers between Commerce and Knoxville. I'd be going 64 mph at most, and in the mountains as slow as 25 mph, but the total distance is shorter.
 

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Being risk averse, I pay more attention to the lower number on the GOM than to the middle one. I sure would hate to run out of juice. Decades ago I ran out of gas on the interstate and the experience cured me of that sort of stupidity.
So that is the beauty of BEV.
If you are running out of juice at highway, take slower roads, or just drive slower, and you will gain 30-50% of your remaining range.
Something that cannot be really done in ICE.

While the low number is the guide for me as well, on days when I know I overdone it, I just go slower and steady speed avoiding any regen at all.
I found on a 60 mile trip (round trip) at steady speed of 50 mph you get about 5.0 mil/kWh.
However, in city, when regen is used, and speeds are between 40-45 - I cannot get to this number despite slower driving. While no regen would bring it even lower, still being at 70% efficient of returning the energy, the number gets to 4.7 or so.
 

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Oops, I didn't mean just driving time, I meant total trip time including a meal and charging sessions. But maybe I have been making one too many charging stops. I've been making 3 stops per trip. Being risk averse, I pay more attention to the lower number on the GOM than to the middle one. I sure would hate to run out of juice. Decades ago I ran out of gas on the interstate and the experience cured me of that sort of stupidity.

Now I'm wondering about staying off the interstate in Georgia and going up US 441 where there are no EA chargers between Commerce and Knoxville. I'd be going 64 mph at most, and in the mountains as slow as 25 mph, but the total distance is shorter.
Assuming meals or restroom breaks (which you would take in any car) can be combined with charging, reduce the charging time by the time spent doing these other activities to calculate trip time difference ICE vs EV.

Example, 30 minute charge stop, with 20 minute meal, you added 10 minutes to the trip waiting for the charging. Assuming the same speeds you would drive in an ICE, that trip is just 10 minutes longer. Restroom break with 20 minute charging, if it would have been 10 minutes in ICE, add 10 minutes to elapsed time.

Slower speed will result in better efficiency. The sweet spot may be 45MPH or so, but 65MPH will be more efficient than 75MPH. If the slower speed route is shorter, this could wash out, if it eliminates a charge stop.

It really takes some math to work these things out. ABRP does a decent job of estimating things for you, so use it on the alternate routes to compare.
 

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Assuming meals or restroom breaks (which you would take in any car) can be combined with charging, reduce the charging time by the time spent doing these other activities to calculate trip time difference ICE vs EV.

Example, 30 minute charge stop, with 20 minute meal, you added 10 minutes to the trip waiting for the charging. Assuming the same speeds you would drive in an ICE, that trip is just 10 minutes longer. Restroom break with 20 minute charging, if it would have been 10 minutes in ICE, add 10 minutes to elapsed time.

Slower speed will result in better efficiency. The sweet spot may be 45MPH or so, but 65MPH will be more efficient than 75MPH. If the slower speed route is shorter, this could wash out, if it eliminates a charge stop.

It really takes some math to work these things out. ABRP does a decent job of estimating things for you, so use it on the alternate routes to compare.
Maybe we should set up a basic heuristic for people to better understand the actual differences in travel time. The following is based on my experiences in my 2017 Chevy Bolt EV and my travel preferences, assuming the final destination is the primary goal (i.e., not a road trip):
  • A 200-mile trip takes the same time in a Bolt EV as it does in an ICE car (assuming no stops in either vehicle).
  • A 300-mile trip takes 15 minutes longer in a Bolt EV than it does in an ICE car (assuming a single bathroom stop in both vehicles).
  • A 400-mile trip takes 15 minutes longer in a Bolt EV than it does in an ICE car (assuming a typical meal stop in both vehicles).
  • A 500-mile trip takes 45 minutes longer in a Bolt EV than it does in an ICE car (assuming a typical meal stop, a bathroom stop, and a fueling stop for the ICE car).
  • A 600-mile trip takes 1 hour longer in the Bolt EV than it does in an ICE car (assuming a typical meal stop, two bathroom stops, and a fueling stop for the ICE car).
  • A 700-mile trip takes 1 hour 30 minutes longer in the Bolt EV than it does in an ICE car (assuming a typical meal stop, two bathroom stops, and a fueling stop for the ICE car).
  • An 800-mile trip takes 1 hour 30 minutes longer in the Bolt EV than it does in an ICE car (assuming two typical meal stops, two bathroom stops, and a fueling stop for the ICE car).
It's important to remember that toward the end, we're talking about 11 to 12 hours just driving. Yes, a one and a half hour difference is significant at that point, but if you're not taking regular breaks including meal stops after that much driving, I really wouldn't want to be sharing the road with you anyway, and there are often ways to maximize that additional down time in the Bolt EV.

This is also the type of assessment I use to determine what an EV's capabilities would need to be in order to replace an ICE vehicle without compromise. On a basic level, to match an ICE car's convenience on long trips, it would be a minimum of 300 miles of freeway speed range (close to 400 mile EPA-rated range) and roughly double the Bolt EV's effective charging speed (400 mi/hr average charging speed). To exceed an ICE car's convenience on long trips, it would need 400 miles of freeway speed range (close to 500 mile EPA-rated range) and (maybe ironically) roughly double the Bolt EV's effective charging speed (or 400 mi/hr average).
 

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Maybe we should set up a basic heuristic for people to better understand the actual differences in travel time. The following is based on my experiences in my 2017 Chevy Bolt EV and my travel preferences, assuming the final destination is the primary goal (i.e., not a road trip):
  • A 200-mile trip takes the same time in a Bolt EV as it does in an ICE car (assuming no stops in either vehicle).
  • A 300-mile trip takes 15 minutes longer in a Bolt EV than it does in an ICE car (assuming a single bathroom stop in both vehicles).
  • A 400-mile trip takes 15 minutes longer in a Bolt EV than it does in an ICE car (assuming a typical meal stop in both vehicles).
  • A 500-mile trip takes 45 minutes longer in a Bolt EV than it does in an ICE car (assuming a typical meal stop, a bathroom stop, and a fueling stop for the ICE car).
  • A 600-mile trip takes 1 hour longer in the Bolt EV than it does in an ICE car (assuming a typical meal stop, two bathroom stops, and a fueling stop for the ICE car).
  • A 700-mile trip takes 1 hour 30 minutes longer in the Bolt EV than it does in an ICE car (assuming a typical meal stop, two bathroom stops, and a fueling stop for the ICE car).
  • An 800-mile trip takes 1 hour 30 minutes longer in the Bolt EV than it does in an ICE car (assuming two typical meal stops, two bathroom stops, and a fueling stop for the ICE car).
It's important to remember that toward the end, we're talking about 11 to 12 hours just driving. Yes, a one and a half hour difference is significant at that point, but if you're not taking regular breaks including meal stops after that much driving, I really wouldn't want to be sharing the road with you anyway, and there are often ways to maximize that additional down time in the Bolt EV.

This is also the type of assessment I use to determine what an EV's capabilities would need to be in order to replace an ICE vehicle without compromise. On a basic level, to match an ICE car's convenience on long trips, it would be a minimum of 300 miles of freeway speed range (close to 400 mile EPA-rated range) and roughly double the Bolt EV's effective charging speed (400 mi/hr average charging speed). To exceed an ICE car's convenience on long trips, it would need 400 miles of freeway speed range (close to 500 mile EPA-rated range) and (maybe ironically) roughly double the Bolt EV's effective charging speed (or 400 mi/hr average).
Sounds about right. A Tesla won't do a while lot better, maybe 15-20 minutes less on the 500-600 mile stretches? Didn't you do an LA <> LVG run with a Bolt vs Model 3? I seem to recall the time difference was not too large.

At my advanced age (62), 500-600 miles in a day is about the max I can do in an ICE. The extra 45-60 minutes of elapsed time isn't as relevant as the fatigue from road time. In fact, my expectation is I would be slightly less fatigued due to longer breaks mid-route.

But, this assumes adequate charging too, which we are getting closer to, but in some areas, not there yet.
 
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