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Percentage or Miles/Kilometers : which do you use and why?

So which do you use or how do you decide and why?

  • Miles/kilometers Only

    Votes: 96 32.1%
  • Percentage Only

    Votes: 128 42.8%
  • Switch back and forth often

    Votes: 12 4.0%
  • Mostly Miles/kilometers & some Percentage

    Votes: 26 8.7%
  • Mostly Percentage & some Miles/kilometers

    Votes: 32 10.7%
  • Never gave it any thought and is the way it was delivered

    Votes: 5 1.7%

  • Total voters
    299

JulienW

Active Member
Jul 7, 2018
2,565
2,794
Atlanta
I have been using percentage (so far) since the Miles/Kilometers is displayed as an absolute and not relative to actual Miles/Kilometers driving. Had an ELR and it was relative so milage estimate range changed based on driving habits and made more sense. However percentage means different things for a Performance/AWD, LRRWD, MR, SR+ and SR. Trying Miles/Kilometers now but kinda prefer percentage since it seems more like a real measurement. Also this is the way most other lit-ion devices display so it is more consistent. Plus in Navigation it gives you the end of route estimate in percentage, even if you have Miles/Kilometers selected. Seems Miles/Kilometers might be a better indicator when at a low charge level or it may create more range anxiety. Still they are 2 sides of the same coin. Using Miles/Kilometers also gives you more increments since 100% is only 100 and Miles/Kilometers can be over 300 increments.

So which do you use or how do you decide and why? Have a felling Miles/kilometers Only will be the most selected.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
9,733
11,725
San Diego
I use miles because:

1) Miles directly displays best estimate of available energy, so battery capacity issues (imbalance, degradation) can be readily seen when using miles. Not the case with % - 90% is always 90%, but it could represent a wide range of available energy.

2) Along the same lines, miles represent a constant quantity of energy, while each % is a variable quantity, depending on the battery condition. So % is less predictable quantity; could be an issue when pushing the limits of range.

3) 3x better resolution with miles, if I want to track exactly how much of the battery I use for whatever reason.
 

Missile Toad

Member
Aug 30, 2016
616
593
Houston
I like miles. If I have 100 on the Instrument Cluster, and my destination is 84 miles to go and I'm traveling with the same levels of precipitation, wind and terrain, then I should feel confident to reach my destination if at 50 miles (when the Instrument Cluster changes the battery logo to amber), I am 42 miles or closer to my destination.

Incidentally, the car will coast at least a mile from 65 MPH, so there is a hidden 'buffer' of an extra mile, in kinetic energy, when at highway speeds.
 
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darth_vad3r

Well-Known Sith
May 6, 2019
1,574
1,123
Canada
I use miles because:

1) Miles directly displays best estimate of available energy, so battery capacity issues (imbalance, degradation) can be readily seen when using miles. Not the case with % - 90% is always 90%, but it could represent a wide range of available energy.

2) Along the same lines, miles represent a constant quantity of energy, while each % is a variable quantity, depending on the battery condition. So % is less predictable quantity; could be an issue when pushing the limits of range.

3) 3x better resolution with miles, if I want to track exactly how much of the battery I use for whatever reason.

You should switch to km to get 1.6x better resolution ;)
 

gilscales

Active Member
Jul 16, 2016
1,684
1,904
Long Beach, CA
I switched to percentage and immediately my wife asked that I change it back to miles, she feels better about seeing how many miles are remaining even though we only average 80 to 85% efficiency
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
9,733
11,725
San Diego
You should switch to km to get 1.6x better resolution ;)

This is true. I should do this. Thanks for the suggestion!

Sadly, it is going to convert everything over including things that actually do have units of km, rather than just energy. And the US just isn’t ready for that yet!
 
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TT97

Active Member
Aug 6, 2017
2,173
2,909
Los Angeles
I switched to percentage and immediately my wife asked that I change it back to miles, she feels better about seeing how many miles are remaining even though we only average 80 to 85% efficiency

Funny, I switched to percentage because of my wife. Every time the remaining range got even close to 100 she would start getting range anxiety (even though we may be less than 5 miles from home). With percentage, she doesn't fret.

Also, the navigation uses percentage so this way the displays match.
 

Leafdriver333

Somewhat Active Member
Mar 21, 2019
1,070
824
usa
I use percentage for commuting. Since I don't plug in daily I pay attention to the percentage and plug in when it is near 20%. This happens every 3 days or so.

When I travel long distance I like to see miles remaining. Supercharger is mapped out before I leave the house for the trip
 

clostridium

Member
Mar 6, 2017
316
291
NE Ohio
I like miles. If I have 100 on the Instrument Cluster, and my destination is 84 miles to go and I'm traveling with the same levels of precipitation, wind and terrain, then I should feel confident to reach my destination if at 50 miles (when the Instrument Cluster changes the battery logo to amber), I am 42 miles or closer to my destination.

Incidentally, the car will coast at least a mile from 65 MPH, so there is a hidden 'buffer' of an extra mile, in kinetic energy, when at highway speeds.

You are only confident to reach your destination if you are getting rated efficiency or better. If I lived in a place where the temperature was 60+ most of the time and it didn't rain much I'd put my car on miles too. The reality is that I don't live in that place so I find percentage more useful. I know in good weather I get 3 miles per percentage point (250 Wh/mi) and in crappy winter weather or really heavy rain I could get as bad as 2 miles per percentage point (375 Wh/mi). Practically speaking I'd prefer if it would report both percentage and actual kWh remaining.

Craig
 

darth_vad3r

Well-Known Sith
May 6, 2019
1,574
1,123
Canada
You are only confident to reach your destination if you are getting rated efficiency or better. If I lived in a place where the temperature was 60+ most of the time and it didn't rain much I'd put my car on miles too. The reality is that I don't live in that place so I find percentage more useful. I know in good weather I get 3 miles per percentage point (250 Wh/mi) and in crappy winter weather or really heavy rain I could get as bad as 2 miles per percentage point (375 Wh/mi). Practically speaking I'd prefer if it would report both percentage and actual kWh remaining.

Craig

Re-read what they wrote. If 84 miles away with “100” remaining, and then later in the same trip at “50” remaining but 42 or less to destination it’s a safe bet to make it to destination if conditions are equivalent.

This example is specifically WORSE than rated efficiency.
 
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FlyinLow

Enjoy the journey
Feb 5, 2018
335
328
29036
1. I see people that are using “miles” occasionally telling stories about how they were seeing only a couple miles remaining before charging.

1a. This is how a person can be stranded. Windshield wipers, HVAC and everything else uses “miles” too. People report going from 10 miles to 3 miles remaining in seconds as the car updates its estimate.

2. Getting down to 5% is low, but if I were displaying miles it might show 13 miles. Unless I’m being careful and not using the HVAC there’s no way I’m going 13 miles.

3. For me % is an energy thing. Remember when we used to drive our gasoline cars down to 1/8th of a tank or so, then fill up? Some filled up at a 1/4 tank. 20% is below a 1/4 tank (1/5).

4. Things are different now because I fuel my car every night, but only partially (80%). On a road trip I don’t even fill up when I stop. Totally different than my gasoline car.

5. Battery life and care are tied to % not miles in my mind. Daily use the way I understand it should be between 80 and 20%, so I bought the size battery that would do that for my family (S85).

Truth be told, one can interpret “%” by looking at the green portion of the battery icon while displaying miles.
 

Snow Drift

[Off-Road Assist] Activated
Feb 10, 2016
1,968
1,497
Long Island
Percent is the only reliable value. The battery actually has that much remaining charge.

Miles is an assumption based on the EPA rating. It does not change based on your driving habits. This would give you a false sense of range since your habits, elevation, temperature, wind, etc, will all impact the range lower.

I believe navigation range at destination adjusts with driving (or at least your avg kWh/mi), and the Energy Consumption screen for a trip will show expected vs. EPA range.
 

darth_vad3r

Well-Known Sith
May 6, 2019
1,574
1,123
Canada
Percent is the only reliable value. The battery actually has that much remaining charge.

Miles is an assumption based on the EPA rating.

% is actually different over time as your battery degrades. So it’s not as reliable as miles (to determine remaining charge), since miles is a *calculation* (not an assumption) based on remaining charge estimate and rated efficiency.
 
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  • Informative
Reactions: Rocky_H

jerry33

(S85-3/2/13 traded in) X LR: F2611##-3/27/20
Mar 8, 2012
19,724
22,767
Texas
The percent I use is the percent on the Nav, which generally increases as I drive. That is, if I start at 5%, after a short time, it's usually 15% and might go as high as 25% by the time I reach the next charging stop.
 

derotam

Member
Oct 31, 2018
825
701
Oak Hill, VA
So for all those who use % remaining because they feel that is more reliable....When your battery degrades do you think that the car will degrade in % when you charge? Meaning, if your car's battery has degraded 10% do you think when you do a full charge it will say 90%? If it does, then great, but if it doesn't then it is just a useless.

Would be great to hear from someone who has measurable degradation(by actual drive testing) to share what % and miles shows.
 

Snow Drift

[Off-Road Assist] Activated
Feb 10, 2016
1,968
1,497
Long Island
% is actually different over time as your battery degrades. So it’s not as reliable as miles which is a *calculation* based on remaining charge estimate and rated efficiency.
But the calculation is based on 310 miles of range. If the battery degrades, you can't go 310 miles, so how is that more reliable?

So for all those who use % remaining because they feel that is more reliable....When your battery degrades do you think that the car will degrade in % when you charge? Meaning, if your car's battery has degraded 10% do you think when you do a full charge it will say 90%? If it does, then great, but if it doesn't then it is just a useless.

Would be great to hear from someone who has measurable degradation(by actual drive testing) to share what % and miles shows.
Miles is based on EPA, so if the battery degrades your miles won't adjust either. At least while the battery is new the % value is accurate, while miles is an assumption based on lab results, which we also know are provided by the OEM and can be +/-.

Battery degredation seems to be pretty low. -10% in 160k (https://electrek.co/2018/04/14/tesla-battery-degradation-data/)
 
Last edited:
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Reactions: karn101 and Rocky_H

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
9,733
11,725
San Diego
Miles is based on EPA, so if the battery degrades your miles won't adjust either

Yes they do. That is because miles are not based on EPA - they are based on the energy the car thinks is available. We see people discussing how they don’t have the full 310/325 miles all the time here.

But the calculation is based on 310 miles of range. If the battery degrades, you can't go 310 miles, so how is that more reliable?

Because when it degrades or is imbalanced it will display a smaller number for a full charge.
 

darth_vad3r

Well-Known Sith
May 6, 2019
1,574
1,123
Canada
But the calculation is based on 310 miles of range. If the battery degrades, you can't go 310 miles, so how is that more reliable?


Miles is based on EPA, so if the battery degrades your miles won't adjust either. At least while the battery is new the % value is accurate, while miles is an assumption based on lab results, which we also know are provided by the OEM and can be +/-.

Battery degredation seems to be pretty low. -10% in 160k (Tesla battery degradation at less than 10% after over 160,000 miles, according to latest data - Electrek)

The degradation issue is exactly why miles is more reliable to use!

You quoted me before I edited to clarify a bit, but what’s more reliable?

(a) “155 miles remains” means half of your original capacity for the life of the car, or
(b) “50%” mean’s half of your current capacity, which could be same as above on day 1, or 45% of original capacity if you have -10% degradation.

They don’t tell you what “100%” is equivalent to unless you display miles and back-calculate from current % to extrapolate or charge to 100%. If you display miles or km, you know how much energy the pack thinks it has. If you display %, you know it thinks it has x% of some other number you don’t know.
 

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