[PLP]

I have been wondering on my daily for BEV.
I know which one is better all ICE - of course 45-50 mph, but for EV - well, not so sure.
While one would say lower speed less energy use, holds true, it is not so good anymore when you use regen often.
Regen is, what, about 60% efficient? Give or take a few, or a dozen% as it depends how you are slowing down.

The trip is flat.
Option 1: 11 miles, 27 minutes (stop and go, 25-35 mph)
Option 2: 13 miles, 27 minutes (much more steady speed, 45-50 mph)

If I could roll, without frequent stopping, I would always opt for the shorter one, but that is not the case.


So, any science supported answers?
I tried to do some math, but I gave up - too many variables and I did not have enough data to account for braking (regen), meaning time, distance, and power of braking.

 

[GJETSON]

The trip is flat.
Option 1: 11 miles, 27 minutes (stop and go, 25-35 mph)
Option 2: 13 miles, 27 minutes (much more steady speed, 45-50 mph)

[Edit] Hard to say. Will depend on how fast you have to travel between stops, and how long the stops are. If you are stopped for 50% of the cross town time, and actually average 50 mph-70 mph moving average, then option 2 is definitely better.

 

[MisterJJ]

Like you said... too many variables. Best to just make a few trips one way and a few trips the other way, noting the usage, and compare.

I'm betting option 1 will be best. Just to be contrary to GJETSON.
Just kidding, but I do think 1 would probably be best, based on experience. But if you have to hit the real brakes occasionally with the stop and go, that'll make it a loser.

 

[Voldar]

The one with steady speed is always the best. The car doesn’t use more energy at a steady speed than in a traffic stop-and-go. The regen doesn’t offset the losses due to constant acceleration/deceleration. Especially in winter time, you will be a lot better with a steady speed than stop&go, even if higher speeds.
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I don’t know about other EV, but here is how I drive my Bolt EV:
- I always try to arrive at the charging DCFC station with about 10% SOC and I drive at the speed that allows me to get there with that SOC.

So, if I have to drive 170 miles and to get there with 10% SOC I need to drive 60 mph, I will do just that. If I have to drive 140 miles and to get there with 10% SOC I need to drive 75 mph, I will do that.

I try to maximize the 10%-60% SOC charging speed bracket that’s the optimal time spend at a charger for the Bolt EV.

 

[Martin D]

I’m with mister JJ on this one. Two miles less is going to be hard to make up from less stops.

 

[jefro]

I'd drive 45 if I could set cruise control.

I keep saying that regen doesn't provide as much as people think. It is something but no where near what you used to get up to speed. My magic ratio is 1/5 return.

 

[redpoint5]

Driving the average speed of traffic minimizes braking, but it's unclear if that method is feasible where you are. When I do this in my Acura TSX in the parking lot that is Portland rush hour, I get better fuel economy than steady 70 MPH cruising. You'd think that letting a huge gap develop when traffic mashes the accelerator, only to slow a few yards down the road would have people jumping into that gap and you'd never get anywhere. The thing is, those people that are constantly changing lanes will move into your gap, and later move out.

I counted how many vehicles moved into the gap I allowed to form, and subtracted each time they moved out. Over the course of an hour of gridlock, only an additional 14 cars occupied that gap. In other words, that strategy over an hour duration added 14 car lengths to my commute, or maybe a minute or 2.

I've only tested this method in Portland, however.

Back to your question, this is a totally testable scenario, and my hunch is the shorter route is more efficient. Personally, I'd take whichever route got me to the destination quickest, if even it was only a few seconds difference. Those seconds add up over the course of 500 trips in a year.

 

[Voldar]

Back to your question, this is a totally testable scenario, and my hunch is the shorter route is more efficient. Personally, I'd take whichever route got me to the destination quickest, if even it was only a few seconds difference. Those seconds add up over the course of 500 trips in a year.

Scenario A : 11 miles @ 25 mph : T = 11 / 25 = 0.44 h ; @ 35 mph : T = 0.31 h
Scenario B : 13 miles @ 45 mph : T = 13 / 45 = 0.28 h ; @ 50 mph : T= 0.26 h
So, there is a 0.2 h (12 mins) [or 0.05 h = 3 mins] difference between the two and in fact the time difference is bigger being that the scenario A is a stop&go traffic and not a steady speed.

In the scenarios presented by the OP, both are done in the same amount of time.
This means only one thing : in stop and go traffic, the OP is accelerating a lot faster and he brakes a lot harsher to make up for the 1.8 mins (sic) difference (minimum). This means a lot more power needed to accelerate and a lot less recuperated power in deceleration. In the end, a lot more power used in stop&go vs steady speed. Add winter in the mix with slippery roads and the power needed to accelerate to the posted speed from a full stop is even more important. With the multiple stops, your energy usage will be a lot more than what you think. Facts based on my experience.

 

[atc98092]

Seems strange that driving significantly faster with fewer stops doesn't show at least some reduction in travel time. But as mentioned, too many variables to state for certain which would be "better". But here's something else to consider: while driving in stop/go traffic, your stress level is liable to be increased, even if you're not aware of it. Driving at a steady pace will likely find you more refreshed and alert when you reach your destination. And that might make it the better drive, even if the slower one is slightly more efficient (but I don't think it is).

 

[Brad]

Like others, I would say option 1 is better. Why not make it scientific? Test both routes by driving a week on one route, and then the next week on the other route? And report back your findings!

 

[cwerdna]

^^^
Yep.

Reset your miles per kWh display. Make a note of your efficiency at the end of each roundtrip then reset. Also, either make a note of how many kWh were consumed for each trip or your begin and end % SoC (you will need to use the My Chevrolet app to see the 1% increment SoC).

 

[jefro]

Tell us what went better.

 

[PLP]

Guys,
thanks a lot for so many responses.

I will not quote each individual, as that would be too messy, so I will recap some points here.

Testing.
I would love to test it. However, Bolt's system is not so clever to allow me for easy testing. See attached - Fiat 500e trip summary. Great info.
The 5-mile bar in Bolt - yeah... kind of useful for maybe overall driving, but not from trip to trip.

As for the trips.
The times are by Google maps. I did not measure, although it seems the shorter one is actually faster overall. I did not measure anything to make a justified decision.

Trip 1.
Oh yeah, all of you you said or thought that I will push the pedal were darn right. It always seems that the time is running crazy fast and you are loosing minutes when stopped in traffic. Like atc98092 said, the shorter trip is more stressful.
And yes, I must hit the friction brakes to stop the car.

Trip 2.
The very big unknown is the train crossing. Then, traffic lights are not synchronised (actually in none of the trips), so I cannot really time it.


I personally lean towards the steady trip.
I moved to a new house, so the route to work was altered. Previously, about 2 miles from the house, I would hit the section of the road where the lights are timed and I learnt that "if I hit an early green here, by doing 47 mph steady I will go through all of them, until I may or may not need to stop about 6 miles down the road, where the timing ends".

 

[GJETSON]

I would love to test it. However, Bolt's system is not so clever to allow me for easy testing

Zero the trip odo, average speed, and center screen energy use, before each run. At start of run, set the timer too. At the end of the run, you can record your total time, moving average, mi/kWh, and mi/ kWh for each 5 mile segment. Not as convenient as if the car did it for you, but all the info is there.

I vaguely recall using the Torque pro trip recording feature a few times, four years ago. It logged a map of my drive, time, speeds , etc. Fascinating, but way more info than I would ever want to see....more than once.

 

[PLP]

Zero the trip odo, average speed, and center screen energy use, before each run. At start of run, set the timer too. At the end of the run, you can record your total time, moving average, mi/kWh, and mi/ kWh for each 5 mile segment. Not as convenient as if the car did it for you, but all the info is there.

I vaguely recall using the Torque pro trip recording feature a few times, four years ago. It logged a map of my drive, time, speeds , etc. Fascinating, but way more info than I would ever want to see....more than once.

1. Zero the trip odo
2. average speed
3. center screen energy use, before each run
4. At start of run, set the timer too
5. At the end of the run

you can record your total time, moving average, mi/kWh, and mi/ kWh for each 5 mile segment. Not as convenient as if the car did it for you, but all the info is there.


You see how many steps there are? I lost count
Yeah, I could do screen shots of using Torque, but again - I would have to remember and do calculations each time. I am too lazy for that.
I got 4 cars to take care of

 

[Voldar]

1. Zero the trip odo
2. average speed
3. center screen energy use, before each run
4. At start of run, set the timer too
5. At the end of the run

you can record your total time, moving average, mi/kWh, and mi/ kWh for each 5 mile segment. Not as convenient as if the car did it for you, but all the info is there.


You see how many steps there are? I lost count
Yeah, I could do screen shots of using Torque, but again - I would have to remember and do calculations each time. I am too lazy for that.
I got 4 cars to take care of

Then, if I'd be a smartarse, I would say, why ask in the first place ?
It's true though, you have everything in the DIC if you want to do the testing by yourself. And the Infotainment to show you how many kWh used. I still have a feeling that the steady speed would be the best option, but for now it's only a "gut feeling". You can prove me wrong though. I dare you !

I know for a fact that on a stop&go vs steady speed commute of the same speed "limit", the steady speed commute wins. What I don't know is what would be the speed difference between the two commutes that would make the stop&go a winner.

 

[GJETSON]

Yeah, I could do screen shots of using Torque,

You don't have to do screen shots. You can set up your Torque Pro to automatically start recording a log every time the car starts. You can preselect what you want recorded. I don't care enough to do it.

 

[MisterJJ]

I personally lean towards the steady trip.

I'd say got with this then.

I used to have a commute where I could take a left and follow a main road with a few lights the rest of the way to work or I could go straight and then make a few turns through a neighborhood which would be slightly faster. I would always make the left down the less complicated route and take a minute or two longer.

 

[redpoint5]

Wait a minute, you have Torque? That should make it simple to find efficiency then since it has any number of gauges, some of which can be reset with the "Trip Reset" button in a single press.

I've got it in my truck, and every trip I see distance traveled, trip time, MPG average, fuel used, average speed...

 

[PLP]

Then, if I'd be a smartarse, I would say, why ask in the first place ?

Because I can. Folks on NextDoor write about their dogs smiling at them or that deer just ate tulips, or that someone broke into a car...

I don't care enough to do it.

that's how I feel.


Generally speaking.

Trip 1 - 27+ traffic lights (those I could count and remember), speed limit up to 35 mph, some places 25 mph. If there was no traffic, or very limited - I would take this one, as I could time the lights, relax, and drive gently. With many cars, and most of them take off when the car in front of them clears off for like two lengths, the anxiety of making it on the green spikes to the roof.

Trip 2 - 15+ traffic lights (as above), speed limit 45 mph with places at 35 mph. Much less traffic.


As for the comment of steady vs stop and go. Well, of course steady is much better. If that was the case - I would not even ask.
However, steady 45-50 mph vs 25-35 mph, shorter trip, but stop and go... that is more splitting hair like situation. I need to drive for 2 miles further at the steady speed. Do I gain overall? Or I buy the comfort of not cursing on the guy who was checking out his crotch, aka looking on the phone, and missed the green light?