Thoughts on Anticipating Range

[OCJoe]

Been driving my new M3 for about a month and enjoying it very much.

I do have a suggestion/question though. Why does range display only in Miles or Percent? I don't find either of these particularly useful. Miles are inaccurate because, well, I indulge in rapid acceleration (NOT complaining, I understand that leadfoot drivers should expect less range.) Similarly, percent of battery remaining isn't very helpful in tracking how far I can expect to go before exhausting the battery.

I'd like to see KWh remaining. That way I can just divide remaining KWh by MY OWN typical KWh per mile and have an accurate sense of range. Anybody know if this is possible?

Also... why does the car display Wh per mile? Anybody who is accustomed to ICE cars thinks in Miles per Gallon, not Gallons per mile. So Miles per KwH seems like a more natural way to express efficiency. (Yes, I understand that one is the reciprocal of the other)

Your thoughts?

 

[JulienW]

....I'd like to see KWh remaining. That way I can just divide remaining KWh by MY OWN typical KWh per mile and have an accurate sense of range. Anybody know if this is possible?....

Your thoughts?

Just take 75 (LR) x Percentage (75x50%=37.5kWh) and you have your kWh remaining. You can then adjust the absolute (75kWh) as you get degradation by charging to 100% and dividing current range by EPA published.

So 300 miles at 100% gives you about 72.75kWh of usable battery.

 

[PianoAl]

Also, you can view the Energy graph, which takes into account your driving style, averaged over the last 30 miles:

 

[PianoAl]

>Miles per KwH seems like a more natural way to express efficiency.

I agree. Humans are weird.

I'd actually like to see the above estimate of projected range and the percent on the main display.

 

[ewoodrick]

Been driving my new M3 for about a month and enjoying it very much.

I do have a suggestion/question though. Why does range display only in Miles or Percent? I don't find either of these particularly useful. Miles are inaccurate because, well, I indulge in rapid acceleration (NOT complaining, I understand that leadfoot drivers should expect less range.) Similarly, percent of battery remaining isn't very helpful in tracking how far I can expect to go before exhausting the battery.

I'd like to see KWh remaining. That way I can just divide remaining KWh by MY OWN typical KWh per mile and have an accurate sense of range. Anybody know if this is possible?

Also... why does the car display Wh per mile? Anybody who is accustomed to ICE cars thinks in Miles per Gallon, not Gallons per mile. So Miles per KwH seems like a more natural way to express efficiency. (Yes, I understand that one is the reciprocal of the other)

Your thoughts?

Switch to percent and you can think of it as a classic gas gauge, 0, 1/2, 1/2, 3/4, F. But much more accurate.

KWh remaining is a little bit of issue, since there is some slight of hand going on. Plus, it is just way to weird for most people to understand.

Wh/mi is probably because it is a bigger number than mi/Wh. My Leaf uses the latter and it show between 4 and 3. It also makes more since, 4 is better than 3. I just personally invert, knowing that 250 is 4 and 333 is 3.

But then again, you think that you know how big the battery is. That number isn't really published. And unlike a fuel tank, it changes.

 

[woodguyatl]

Been driving my new M3 for about a month and enjoying it very much.

I do have a suggestion/question though. Why does range display only in Miles or Percent? I don't find either of these particularly useful. Miles are inaccurate because, well, I indulge in rapid acceleration (NOT complaining, I understand that leadfoot drivers should expect less range.) Similarly, percent of battery remaining isn't very helpful in tracking how far I can expect to go before exhausting the battery.

I'd like to see KWh remaining. That way I can just divide remaining KWh by MY OWN typical KWh per mile and have an accurate sense of range. Anybody know if this is possible?

Also... why does the car display Wh per mile? Anybody who is accustomed to ICE cars thinks in Miles per Gallon, not Gallons per mile. So Miles per KwH seems like a more natural way to express efficiency. (Yes, I understand that one is the reciprocal of the other)

Your thoughts?

Regarding % you don't just like an ICE car with a traditional gas tank gauge. Try it for a while and it will become second nature.

 

[coconutboy84]

I didnt think i would miss the GOM from my 2016 volt, but i really do. it was surprisingly accurate and gave me a good sense of my range day to day. wish tesla would give the option to use the energy graph number where the battery icon is...

 

[AlanSubie4Life]

Wh/mi and gallons per mile make it easier to see how much you are saving, and compare consumption between vehicles.

For example, you save more gas by going from a car that gets 15mpg to one that gets 20mpg than you do going from a car that gets 30mpg to a Prius that gets 50mpg. It’s hard to see that when looking at those numbers!

From a practical standpoint, it also avoids the problem of the mileage value becoming undefined or extremely large when the consumption drops to zero, and deals better with the issue of crossing over to negative values which commonly occur with EVs.

I think some people would be up in arms wanting the other display if your mileage started showing -50 miles/kWh as you started driving down a hill. -20Wh/mi is easier to understand.

That being said, my Spark EV displays miles/kWh...

 

[OCJoe]

Just take 75 (LR) x Percentage (75x50%=37.5kWh) and you have your kWh remaining. You can then adjust the absolute (75kWh) as you get degradation by charging to 100% and dividing current range by EPA published.

So 300 miles at 100% gives you about 72.75kWh of usable battery.

Hi Julien, This is helpful, thanks. I can follow your steps and get to the right answer.

But I guess what I'm looking for is a more direct path to the same info. For example, I have SR+ not LR so need to plug in a smaller number than the 75kWh you propose. Also, I'd rather not have to do a full charge to figure out how much usable battery I have left. Is it unreasonable to ask for a direct indication of remaining usable KWh from the console? If I had that, I could just multiply by 4 (if I'm driving conservatively - 250Wh/mi) or 3 (if I'm driving aggressively - 333Wh/mi) to get a good range estimate. As an aside, I can multiply by 3 or 4 in my head. Unfortunately, the longer list of steps in your proposed method is beyond my limited mental math ability

 

[OCJoe]

Also, you can view the Energy graph, which takes into account your driving style, averaged over the last 30 miles:

Hi Piano Al,

Thank for the reply this is helpful. I have looked at this graph and it's good but it jumps straight to an answer based on the last 5/15/30 miles. Sometimes this is good enough, but what I'm aiming for is a way to apply my own Wh/mi factor to remaining energy. This graph assumes you will continue driving the same way over the same terrain as you were for the past 30 miles. When that's not the case I'd like to be able to apply my own judgement for upcoming Wh/mi.

 

[OCJoe]

Wh/mi and gallons per mile make it easier to see how much you are saving, and compare consumption between vehicles.

For example, you save more gas by going from a car that gets 15mpg to one that gets 20mpg than you do going from a car that gets 30mpg to a Prius that gets 50mpg. It’s hard to see that when looking at those numbers!

Hadn't thought of this - good point.

From a practical standpoint, it also avoids the problem of the mileage value becoming undefined or extremely large when the consumption drops to zero, and deals better with the issue of crossing over to negative values which commonly occur with EVs.

I think some people would be up in arms wanting the other display if your mileage started showing -50 miles/kWh as you started driving down a hill. -20Wh/mi is easier to understand.

Your point is valid for instantaneous Wh/m. I can wrap my head around it either way but I see how it could cause confusion

What I'm seeking is an indication of true usable KWh left in the battery. This would always be a positive value that could be multiplied by my own personal forecasted mi/KWh (something between 3 and 4) to arrive at a much more useful and accurate estimate of range. I'd find this much more useful than the existing range indicators (range in miles, battery percent, and Energy Graph)

 

[OCJoe]

I didnt think i would miss the GOM from my 2016 volt, but i really do. it was surprisingly accurate and gave me a good sense of my range day to day. wish tesla would give the option to use the energy graph number where the battery icon is...

What is GOM?

 

[coconutboy84]

What is GOM?

“Guess-O-meter”

 

[OCJoe]

Regarding % you don't just like an ICE car with a traditional gas tank gauge. Try it for a while and it will become second nature.

Hi Woodguy,

Agree, as I gain experience I'll develop intuition about "X% battery remaining" means "you need to charge in about Y miles." This is similar to the way I intuitively know "1/2, 1/4, 1/8 of a tank of gas left" implies a certain amount range.

While I'm building up that experience I'd like to be able to do a quick-and-dirty mental calculation and I've found it difficult without knowing remaining KWh.

Not saying this in a derogatory way, but EV power consumption per mile seems to be a lot more variable than ICE mpg. Best ever MPG on my old ICE car was 30 and worst ever was 23. I've had some Tesla trips with 260Wh/mi and some with over 500Wh/mi. If I knew the remaining KWhs and then multiplied by my own anticipated mi/KWh, it would give me data to ease range anxiety.

Perhaps this is not right for everyone. But for me, it would be cool to have the ability to monitor remaining KWh directly.

 

[Uncle Paul]

An interesting observation. Some agressive Tesla owners drive like crazy people when their batteries are pretty full, but when they get almost empty they drive like angels

 

[OCJoe]

An interesting observation. Some agressive Tesla owners drive like crazy people when their batteries are pretty full, but when they get almost empty they drive like angels

Guilty as charged, sir.

 

[woodguyatl]

Hi Woodguy,

Agree, as I gain experience I'll develop intuition about "X% battery remaining" means "you need to charge in about Y miles." This is similar to the way I intuitively know "1/2, 1/4, 1/8 of a tank of gas left" implies a certain amount range.

While I'm building up that experience I'd like to be able to do a quick-and-dirty mental calculation and I've found it difficult without knowing remaining KWh.

Not saying this in a derogatory way, but EV power consumption per mile seems to be a lot more variable than ICE mpg. Best ever MPG on my old ICE car was 30 and worst ever was 23. I've had some Tesla trips with 260Wh/mi and some with over 500Wh/mi. If I knew the remaining KWhs and then multiplied by my own anticipated mi/KWh, it would give me data to ease range anxiety.

Perhaps this is not right for everyone. But for me, it would be cool to have the ability to monitor remaining KWh directly.

It does take a little practice an experience. I don't have a good estimate tool for you. Like some many things driving related, I just acquired a "feel" for it over time. I will note though that even ICE cars lose about 20% efficiency on short trips in cold weather. Most people just don't pay attention.

 

[Rocky_H]

Also... why does the car display Wh per mile? Anybody who is accustomed to ICE cars thinks in Miles per Gallon, not Gallons per mile. So Miles per KwH seems like a more natural way to express efficiency. (Yes, I understand that one is the reciprocal of the other)

How very American-centric of you!!
I don't suppose you realize that efficiency figures in the European standards use a different figure than miles per gallon. They are liters per 100 km, so it is fuel per distance, just like the Tesla system is showing, where the lower number is more efficient.