Optimal Cruising Speed to Minimize Time

[SSonnentag]

Bjørn Nyland did some testing and posted a video, comparing the Wh/(k)m at various speeds for the S, X and I-Pace. He then did more testing to find the optimal driving speed to minimize time driving and charging. I took his data and made a couple of graphs, extending the trend lines a bit in either direction to fill in a bit more data. I used a 2nd order polynomial fit.

Anyway, I thought the data was interesting, although probably not too useful. Have a look.

 

[David29]

Just want to verify what you mean by "effective speed." It sounds as if you mean, what is the net speed you can travel, accounting for charging time. So, if I read you right, you are saying that the optimal speed to minimize time is something around 110 mph, at which the "effective speed" is about 65 mph. Do I have that right? Certainly seems counter-intuitive, and as you say, not very practical!

By the way, I think the convention is to title a graph as "Y variable as a function of [or "Vs"] X variable," so the upper graph would be Wh/mi vs. Speed (mi/hr), etc.

 

[SSonnentag]

Just want to verify what you mean by "effective speed." It sounds as if you mean, what is the net speed you can travel, accounting for charging time. So, if I read you right, you are saying that the optimal speed to minimize time is something around 110 mph, at which the "effective speed" is about 65 mph. Do I have that right? Certainly seems counter-intuitive, and as you say, not very practical!

By the way, I think the convention is to title a graph as "Y variable as a function of [or "Vs"] X variable," so the upper graph would be Wh/mi vs. Speed (mi/hr), etc.

Yep, you've got it.

X vs Y is what I've always been taught and seen. ???

 

[SSonnentag]

It looks like you are correct.

Dependant variable vs Independent variable

In my cases, the Y axis in the dependant variable. Thanks! It's good to learn new things.

 

[csanders90D]

His numbers for the charging time are assuming a constant charge rate of 99 kW. I'm not sure how he came up with that rate, but I think it's biasing the results towards higher speed driving. Not only are some cars (and some superchargers) not able to handle that much power, but in order to drive faster you'll have to charge the battery to a higher % and waste more time in the slow tapered charge curve.

 

[dbldwn02]

His numbers for the charging time are assuming a constant charge rate of 99 kW. I'm not sure how he came up with that rate, but I think it's biasing the results towards higher speed driving. Not only are some cars (and some superchargers) not able to handle that much power, but in order to drive faster you'll have to charge the battery to a higher % and waste more time in the slow tapered charge curve.

Yea...my car doesn't charge over 60kw for more than a few minutes. I would really like to know this information for road trips.

 

[JohnnyG]

Bjørn Nyland seems like a really nice guy, and his videos are quite entertaining, no doubt about it. But I would use his data with a grain of salt... I've seen way too much misinformation or guesswork out of that channel. His tests usually lack much control and miss many large pertinent factors.