Trying to Understand Efficiency

[Nate977p]

Hello All!

So I have had my P3D for about 13.5k miles now and get efficiency much worse than rated; obviously that is old news.

The part I am confused on is the displayed usage in the car. My understanding is that it does not take into effect heating/cooling when not driving, but does while driving. Take my commute to work this morning.

Starting indicated range: 72.
Ending indicated range: 46.
Drive distance: 18.1 miles (per car).
Temperature: about 25° and sunny.

Commute info: car started 3 stories down in a garage that was 50-60° warm and had been plugged in on 110 (I got the lucky spot!), Thus was not cold soaked. No meaningful elevation change.

Thus with my math, I used 26 miles to go 18.1. Meaning my efficiency was about 69% (quick math, think I did that right). But my car only indicated 316 Wh/mi. If the baseline efficiency for the car at rated range is 250 Wh/mi, wouldn't 69% efficiency be about 362 Wh/mi?

During all this the car did not sit on with the heat on at any point. All this data is from me unplugging the 110, getting right in, driving, and getting out.

Am I messing up the math or missing something?

Thanks!

 

[Runebane]

If you're talking about the miles left, that's a fuel tank. If it helps, switch it to % instead. It's estimating based solely on EPA rating how many miles you have left, but seriously it's just the fuel (energy) tank.

Navigation is supposed to take current temperature and other factors to better estimate how much energy will be used.

 

[BobbyKings]

Not to discredit this topic in any way or fashion, but after driving for about 100k miles (Model S) I have long stopped being worried about efficiency and range. I just don't bother anymore.

In an ICE you fill up when you have to. In an EV you charge when you can. And that turns out to be very convenient.

Enjoy!

 

[Oldschool496]

Not to discredit this topic in any way or fashion, but after driving for about 100k miles (Model S) I have long stopped being worried about efficiency and range. I just don't bother anymore.

In an ICE you fill up when you have to. In an EV you charge when you can. And that turns out to be very convenient.

Enjoy!

My most recent revelation.
I agree being with my S for 2.5 years now. There is so much availability of energy/charging network traveling or otherwise, arrive empty as smart enough to charge quickly and move along quickly. At home/destination speaks for itself.

All my worry is trying to arrive as empty as possible, that's a whole other math problem I never thought I would be concerned about when I bought my EV. Arriving last to charge and leaving before others who arrived before I did. Now thats efficient to me.

 

[Peteski]

If you're talking about the miles left, that's a fuel tank. If it helps, switch it to % instead. It's estimating based solely on EPA rating how many miles you have left, but seriously it's just the fuel (energy) tank.

Navigation is supposed to take current temperature and other factors to better estimate how much energy will be used.

+1
You can also get a pretty accurate projected range figure from the energy page based on the last 5,15 or 30 miles driven. The range figure next to the battery icon is better switched to a simple percentage display otherwise it just causes confusion.

 

[ewoodrick]

Stop looking at the range indicator. It is pretty much like a stopped watch that is right twice a day. Look at the energy usage graph for a better indication of what your current utilization is.

And as other have set, just stop worrying about it. It WILL start to change dramatically in a few months as the temps start to go up.

In the winter, you will loose about 30% of your range, get used to it. 72-46 = 26 miles used 26*70%= 18.2 mile actual range.

Heck, I was pretty darn close!!!

 

[ac_power]

Power meter should show both background drain and driving style overhead.
Everything else will be battery capacity drop, as 50..60 F is still fairly low for Li-Ion which likes 100 F much better.
Miles or % - it's still an abstract number not attached to driving conditions.

 

[SageBrush]

Arithmetic looks correct to me, I cannot explain the discrepancy

 

[Nate977p]

I was hoping the thread didn't go this path, but on retrospect my question wasn't as clear as it could be and I may have misplaced terms.

My question was: the Wh/mi average seems much lower than what it should be. In my test, I used 26 miles to go 18.1 miles with no idling. The car should have showed a consumption much more than the average that was displayed of 316, closer to 360 should have been actual. Am I missing something?

As for the other points, replied to quotes:

If you're talking about the miles left, that's a fuel tank. If it helps, switch it to % instead. It's estimating based solely on EPA rating how many miles you have left, but seriously it's just the fuel (energy) tank.

Navigation is supposed to take current temperature and other factors to better estimate how much energy will be used.

I agree with your perspective and do not trust the EPA. At fill charge, I assume I have 160-200 of real range. I have driven 13.5k since last week of September, and have no reliable home or work charging. I am very aware of the losses (although did not anticipate them being so bad). The navigation is constantly off; typically a few % for every 20-30 min.

[QUOTE"BobbyKings, post: 3412115, member: 39827"]Not to discredit this topic in any way or fashion, but after driving for about 100k miles (Model S) I have long stopped being worried about efficiency and range. I just don't bother anymore.

In an ICE you fill up when you have to. In an EV you charge when you can. And that turns out to be very convenient.

Enjoy![/QUOTE]

As replied to quote above, I am constantly planning ahead. I love the car, but driving nearly 1000 miles a week with no reliable charging means I am always planning ahead! Having accurate data is important to that planning

My most recent revelation.
I agree being with my S for 2.5 years now. There is so much availability of energy/charging network traveling or otherwise, arrive empty as smart enough to charge quickly and move along quickly. At home/destination speaks for itself.

All my worry is trying to arrive as empty as possible, that's a whole other math problem I never thought I would be concerned about when I bought my EV. Arriving last to charge and leaving before others who arrived before I did. Now thats efficient to me.

I'm always on the hunt for electrons! Yesterday I hit 0 miles indicated and still had about half a mile to go!

+1
You can also get a pretty accurate projected range figure from the energy page based on the last 5,15 or 30 miles driven. The range figure next to the battery icon is better switched to a simple percentage display otherwise it just causes confusion.

Yes, I tend to default to the 30 miles, but on my longer drives, would like to see the Wh/mi average for more accurate planning

Stop looking at the range indicator. It is pretty much like a stopped watch that is right twice a day. Look at the energy usage graph for a better indication of what your current utilization is.

And as other have set, just stop worrying about it. It WILL start to change dramatically in a few months as the temps start to go up.

In the winter, you will loose about 30% of your range, get used to it. 72-46 = 26 miles used 26*70%= 18.2 mile actual range.

Heck, I was pretty darn close!!!

I have had car since end of September and have seen the temperature hit. I don't trust rated, in fact I assume about 1/2 of rated is my actual + 20 mile buffer to be safe. I am specifically talking about the Wh/Mi gauge.

Power meter should show both background drain and driving style overhead.
Everything else will be battery capacity drop, as 50..60 F is still fairly low for Li-Ion which likes 100 F much better.
Miles or % - it's still an abstract number not attached to driving conditions.

Agreed 50-60 is still low, but it's not fully cold soaked and was plugged in. Regardless my point is not being surprised by efficiency losses. It's that my Wh/Mi gauge seems very off.

On a side note, I don't get everyone saying use % vs miles. May just be how my brain works, but I divide indicated range by half, and that is fairly accurate, plus some safety buffer (about 20 miles on 80% charge). Using percent, I would have to multiply by 1.5. I think my brain just works better at division than multiplication? Or I'm stubborn!

 

[ac_power]

On a side note, I don't get everyone saying use % vs miles. May just be how my brain works, but I divide indicated range by half, and that is fairly accurate, plus some safety buffer (about 20 miles on 80% charge).

That's funny - when learning to fly cross-country in a glider, you do about same calculations on the safe gliding range. I thought EVs are a little safer.
The point of miles vs % is that in either case it's an abstract number not attached to the driving conditions. % is just clearly abstract, while miles may be misinterpreted as practical range.
EV makers took questionable practice of making an accent on EPA numbers, so the dashboard indicator has to follow that, otherwise will be some confusion on new owners. Now the correct range estimate is on power meter graph, and it's completely different number most of the time.
Would be better to switch battery meter into KWh, so it's still fairly abstract like it should be, but (unlike %) would directly correlate with charging, and still show battery aging / degradation when full.

 

[Nate977p]

Not to discredit this topic in any way or fashion, but after driving for about 100k miles (Model S) I have long stopped being worried about efficiency and range. I just don't bother anymore.

In an ICE you fill up when you have to. In an EV you charge when you can. And that turns out to be very convenient.

Enjoy!

Bump as my last reply did not quote you properly

 

[Nate977p]

That's funny - when learning to fly cross-country in a glider, you do about same calculations on the safe gliding range. I thought EVs are a little safer.
The point of miles vs % is that in either case it's an abstract number not attached to the driving conditions. % is just clearly abstract, while miles may be misinterpreted as practical range.
EV makers took questionable practice of making an accent on EPA numbers, so the dashboard indicator has to follow that, otherwise will be some confusion on new owners. Now the correct range estimate is on power meter graph, and it's completely different number most of the time.
Would be better to switch battery meter into KWh, so it's still fairly abstract like it should be, but (unlike %) would directly correlate with charging, and still show battery aging / degradation when full.

Great points and interesting on gliding!

The miles also gives me more granularity than %, maybe that is why I gravitate to it more? But regardless same concept as I apply a divider or multiple to an inaccurate base #.

 

[Peteski]

On a side note, I don't get everyone saying use % vs miles. May just be how my brain works, but I divide indicated range by half, and that is fairly accurate, plus some safety buffer (about 20 miles on 80% charge). Using percent, I would have to multiply by 1.5. I think my brain just works better at division than multiplication? Or I'm stubborn!

It's whatever reference works best for you.

In the UK we don't have EPA range, we have a choice of the even more inaccurate NEDC range or a "typical" range, neither of which are helpful. As it happens I get roughly 200 miles on a 100% charge, so that's an easier conversion to make than attempting to factor the other two range based options I have. A lot of UK owners switch the display to battery percentage for this same reason.

When I need to know an accurate projected range I head for the energy page and the navigation. I find both of those pretty solid, maybe slightly optimistic, but only a few percent out and I can adjust my driving style accordingly if I see that I'm sliding off the projected consumption line.

 

[Oldschool496]

I'm always on the hunt for electrons! Yesterday I hit 0 miles indicated and still had about half a mile to go!

I assume you plugged in or did you try to go further?

You are really cutting it close, either your thrifty, have no access, this is some experiment or just like to live on the wild side. Your not going to have these same results all the time every time again and again and I'm afraid you'll be riding in the passenger seat of a flat bed tow truck shortly after a long wait some day. I don't allow my car to ever get that low by choice 0% or 0 range. Think, wow I just made it with 1/2 mile left. Nobody does that by choice and dare I say more then likely not good for the Battery either. There are factors at play with these batteries, the car may shut down at 15 miles of range showing or 5% or lower.

Even your first post you went from 72 down to 46. Sounds like your in town. This is not an experiment, as I feel your experimenting with your car, instead of using it for reliable transportation. You at least have a LR bat or Mid and I tend to think the former. It says Boston, it must be cold on and off surely, real cold.

Model 3 uses significant energy in cold (as reported by friends who travel into cold areas with their TM3 from Florida), just to heat the cabin if thats what you are doing. It not calculable the same everyday.

A real experiment would be not using the heat, wearing layers and using only the drivers seat heating maybe. Set all other setting so no vampire drain(stop reporting to Tesla via settings if thats possible in Model 3) and see what the results really are.

Slow down and stop punching it off the line. If you want 72 to be 72 try 52MPH, you might get that range in that car. Stop and go forget it, never happen.

 

[Nate977p]

It's whatever reference works best for you.

In the UK we don't have EPA range, we have a choice of the even more inaccurate NEDC range or a "typical" range, neither of which are helpful. As it happens I get roughly 200 miles on a 100% charge, so that's an easier conversion to make than attempting to factor the other two range based options I have. A lot of UK owners switch the display to battery percentage for this same reason.

When I need to know an accurate projected range I head for the energy page and the navigation. I find both of those pretty solid, maybe slightly optimistic, but only a few percent out and I can adjust my driving style accordingly if I see that I'm sliding off the projected consumption line.

I can't imagine having to go by NEDC, thank goodness that WLPT is standardizing (still not perfect but way better). I just might be weird and prefer to divide the miles than multiple the percent.

But this is still my point, the trip energy Wh/Mi seems largely off. Agreed on Nav and energy, but energy only does last 30 miles and I prefer bigger data than that sometimes.

 

[Nate977p]

I assume you plugged in or did you try to go further?

You are really cutting it close, either your thrifty, have no access, this is some experiment or just like to live on the wild side. Your not going to have these same results all the time every time again and again and I'm afraid you'll be riding in the passenger seat of a flat bed tow truck shortly after a long wait some day. I don't allow my car to ever get that low by choice 0% or 0 range. Think, wow I just made it with 1/2 mile left. Nobody does that by choice and dare I say more then likely not good for the Battery either. There are factors at play with these batteries, the car may shut down at 15 miles of range showing or 5% or lower.

Even your first post you went from 72 down to 46. Sounds like your in town. This is not an experiment, as I feel your experimenting with your car, instead of using it for reliable transportation. You at least have a LR bat or Mid and I tend to think the former. It says Boston, it must be cold on and off surely, real cold.

Model 3 uses significant energy in cold (as reported by friends who travel into cold areas with their TM3 from Florida), just to heat the cabin if thats what you are doing. It not calculable the same everyday.

A real experiment would be not using the heat, wearing layers and using only the drivers seat heating maybe. Set all other setting so no vampire drain(stop reporting to Tesla via settings if thats possible in Model 3) and see what the results really are.

Slow down and stop punching it off the line. If you want 72 to be 72 try 52MPH, you might get that range in that car. Stop and go forget it, never happen.

I hit 0 miles about 1/2 mile from a family home. Made it there, plugged in, and had them drive me to the office...

I hit 1-5 miles indicated range probably every other week or every week. Under 20 probably every other day. I do hope the % is accurate shutting down at 5% is not going to be good...

This is not intentional or living on the wild side. I drive about 1000 miles a week with no reliable home or work charging. My parking garage has a 110 outlet I can sometimes get if the parking spot is open near it (50/50). But still that's only 60 miles (rated) a night. My daily commute to our close office is about 40 miles round trip, our other office is about 110 miles. And I travel to clients constantly.

The night I left with 72, I got home late and my option was either drive and sit at a SC till past probably 10pm, then have dinner when I get home, or cut it close the next AM .

Everyone has different situations, mine is just more on the extreme.

Back to my point thoigh, is the Wh/Mi trip gauge just wildly inaccurate?

 

[Nate977p]

A real experiment would be not using the heat, wearing layers and using only the drivers seat heating maybe. Set all other setting so no vampire drain(stop reporting to Tesla via settings if thats possible in Model 3) and see what the results really are.

Slow down and stop punching it off the line. If you want 72 to be 72 try 52MPH, you might get that range in that car. Stop and go forget it, never happen.

Also on these two points, they really grind my gears. I bought this car as a car. I'm not going to not use heat or dress up heavily. I also am not going to blast the heat at 72. And for the speed, try 52 on a highway in the Boston area, you have a great chance of being in an accident or cause one

I am not complaining about efficiency loss. I was surprised it's so severe, but I live with it. Just surprised the trip Wh is so off.

 

[Oldschool496]

Everyone has different situations, mine is just more on the extreme.

Yours is real extreme, while not putting you down at all, this car is probably not the best option for you asking family members to finish your commute or trips. Hopefully you can find a way to mitigate getting others involved in your travels.

Also on these two points, they really grind my gears. I bought this car as a car. I'm not going to not use heat or dress up heavily. I also am not going to blast the heat at 72. And for the speed, try 52 on a highway in the Boston area, you have a great chance of being in an accident or cause one

I am not complaining about efficiency loss. I was surprised it's so severe, but I live with it. Just surprised the trip Wh is so off.

Believe me, I at least if not all, found the system not keeping track of every electron a bit surprising.

On those two points above in your words, now at least you understand fully, run anything outside of driving, there is a cost and thats range, while I agree traveling below 70 on a clear, bright sunny day on a highway, might not be good anywhere. Down here 80+ is the new norm.

How you get started and execute during your travel has impacts. Your keenly aware now.

IF your not experimenting then your certainly increasing your heart rate without the help of illegal substances. Your the poster child for range anxiety, of which, as I stated have moved beyond myself and my anxiety is how quick can I get into the charger and out before others. Arrive as empty as practicable.

Difference, I guess here, is I have options/ you have few it sounds like. Not undoable, just with a few tweaks maybe it could be better?
A little better?

Beyond all this I'm guessing you really love this car, I mean really love it. Thats why we are all here.

 

[Nate977p]

Yours is real extreme, while not putting you down at all, this car is probably not the best option for you asking family members to finish your commute or trips. Hopefully you can find a way to mitigate getting others involved in your travels.



Believe me, I at least if not all, found the system not keeping track of every electron a bit surprising.

On those two points above in your words, now at least you understand fully, run anything outside of driving, there is a cost and thats range, while I agree traveling below 70 on a clear, bright sunny day on a highway, might not be good anywhere. Down here 80+ is the new norm.

How you get started and execute during your travel has impacts. Your keenly aware now.

IF your not experimenting then your certainly increasing your heart rate without the help of illegal substances. Your the poster child for range anxiety, of which, as I stated have moved beyond myself and my anxiety is how quick can I get into the charger and out before others. Arrive as empty as practicable.

Difference, I guess here, is I have options/ you have few it sounds like. Not undoable, just with a few tweaks maybe it could be better?
A little better?

Beyond all this I'm guessing you really love this car, I mean really love it. Thats why we are all here.

On the family members, we are a close family and the office is only 10 min away, so wasn't a big deal, but appreciated!

In my ICE the rated mpg was always very close to actual (few % off at most) thus I am so surprised the Wh/mi is so off.

Actually ironically, I have only had range anxiety once or twice. Getting this close doesn't bother me as I plan far ahead. I don't get somewhere with 40 miles left and no plan on what to do. I always am planning charging a day or two ahead and that's why accurate data is so critical!

And yes I love this car. It's funny, to me it's such a paradigm shift in transit. Not as great as horse and buggy to cars, as that change the global landscape and connected the world. But it makes ICE feel so silly now.

• You are not tied to one fuel source.
• If you want to go fast, you don't lose any real efficiency, compared to ICE where you have to lug a larger or boosted engine around all the time.
• The quiet, lack of emissions, and instant acceleration.
• The OTA updates. Honestly this feels very underrated. The car keeps getting better; that's never been done before to this capacity!

 

[dsvick]

My question was: the Wh/mi average seems much lower than what it should be. In my test, I used 26 miles to go 18.1 miles with no idling. The car should have showed a consumption much more than the average that was displayed of 316, closer to 360 should have been actual. Am I missing something?

I don't know if you'll ever get your numbers to match up the way you want them to. Efficiency is the work produced divided by the work input, so your mileage efficiency is right, 18.1 / 26 = 69.6% you'll always be able to calculate that. But, for your Wh/mi displayed, all it is doing is taking your kWh used and dividing it by the miles driven, it's not taking into account climate control, radio, or anything else.