Stated Battery Capacity / EPA Economy / Mileage Does Not Add Up

[Nate977p]

Ok, I have to question how y'all are driving. I'm in New England, and I commute from NH to Boston. I did 100 miles today round trip for my commute and my car read 195Wh/mi for the trip. Ambient temp was 30F in the morning and 52F in the afternoon. I had the windows cracked on the way home because it was actually hot in the cabin from the sun. Most of my commute is on I-93, half of which is at 65-70mph and the other half in traffic. I rely on EAP heavily for this stretch.

My efficiency number is only going to drop as the weather outside warms up more. Today, I was still regen limited at the start. In May, this commute will drop to around 165Wh/mi.

These are readings from the car and doesn't factor charging losses. But I can't imagine how people are over 300Wh/mi. Are you flooring it at every light and going 90mph on the highway? Even my S is slightly below 300Wh/mi this time of year.

-edit-
grabbed a photo:

View attachment 393000

I probably pass you on the highway often! Can I ask where in NH you are; seen you frequent the forum and think I've passed you on the highway, back when you were one of the few 3s in NE! I live in Boston and commute all over NE for clients (see my last post).

But my lifetime is 330 Wh/mi. Today was 340 Wh/mi. Driving in the exact same temps as you, with warm battery to start.....

 

[ewoodrick]

EPA numbers are based on the electricity going through the wall outlet. In other words charging losses are factored in (about 20%)

Huh? Not only am I pretty sure that this is incorrect, but it also suggest that the Wh/mi should be 20% higher than it is.

If the numbers take charging losses into consideration (which I believe are well below 5%) then if the car needs 250 Wh/mi, then it would take about 300 Wh/mi to run. Or if 20% is calculated in the equation, then the car would actually be getting 200 Wh/mi.

I didn't think that Tesla had ever specifically stated the battery capacity, but that there are a lot of educated guesses out there.

The EPA numbers aren't real, they are actually negotiated numbers between Tesla and the EPA. The actual numbers for the LR RWD are higher. The EPA does publish the real numbers, just search around for actual test results. Non of the models have the same numbers, but Tesla/EPA originally listed them as the same.

In general, 250 wH/mi is the consumption at which you will make the 310 mile range. This only works for a LR AWD with aero covers on, standard driving under 70 mph. and factory tires at full air and, temperatures over 60F.

Since you are in NE and an AWD, your will not reach that range. Current low temps and the extra motor decrease your range. Warmer temps will definitely help, but not much you can do about the extra motor. I think that the EPA numbers go up to about 255 Wh/mi for your car.

But in any case, it's easy to beat the number, stay below 70 mph, and in the performance, WELL below 70 mph. And with bigger wheels, you have to go even slower to reach 250 Wh/mi and hit 310 mile range in the LR battery.

Since so many folks have bought their first EV in the last 6 months, few have gotten to understand range when the temps are warm. I've had a Leaf for 5 years and 250 Wh/mi or better comes in the summer, while 330 Wh/mi is what I get in the winter in Atlanta.

So, just chill out for a few weeks until the temps hit the 70s and then stop being chilly and see what the real numbers start to be.

 

[Daniel in SD]

Huh? Not only am I pretty sure that this is incorrect, but it also suggest that the Wh/mi should be 20% higher than it is.

If the numbers take charging losses into consideration (which I believe are well below 5%) then if the car needs 250 Wh/mi, then it would take about 300 Wh/mi to run. Or if 20% is calculated in the equation, then the car would actually be getting 200 Wh/mi.

I didn't think that Tesla had ever specifically stated the battery capacity, but that there are a lot of educated guesses out there.

The EPA numbers aren't real, they are actually negotiated numbers between Tesla and the EPA. The actual numbers for the LR RWD are higher. The EPA does publish the real numbers, just search around for actual test results. Non of the models have the same numbers, but Tesla/EPA originally listed them as the same.

In general, 250 wH/mi is the consumption at which you will make the 310 mile range. This only works for a LR AWD with aero covers on, standard driving under 70 mph. and factory tires at full air and, temperatures over 60F.

Since you are in NE and an AWD, your will not reach that range. Current low temps and the extra motor decrease your range. Warmer temps will definitely help, but not much you can do about the extra motor. I think that the EPA numbers go up to about 255 Wh/mi for your car.

But in any case, it's easy to beat the number, stay below 70 mph, and in the performance, WELL below 70 mph. And with bigger wheels, you have to go even slower to reach 250 Wh/mi and hit 310 mile range in the LR battery.

Since so many folks have bought their first EV in the last 6 months, few have gotten to understand range when the temps are warm. I've had a Leaf for 5 years and 250 Wh/mi or better comes in the summer, while 330 Wh/mi is what I get in the winter in Atlanta.

So, just chill out for a few weeks until the temps hit the 70s and then stop being chilly and see what the real numbers start to be.

This is incorrect. The EPA Wh/mi numbers are based on the EPA test procedure (which is conducted by the manufacturer). The LR gets 270Wh/mi, the AWD gets 290Wh/mi, it's right on the window sticker. You're thinking of the range number which is allowed to be downgraded by the manufacturer .

 

[Ejl80]

Huh? Not only am I pretty sure that this is incorrect, but it also suggest that the Wh/mi should be 20% higher than it is.

If the numbers take charging losses into consideration (which I believe are well below 5%) then if the car needs 250 Wh/mi, then it would take about 300 Wh/mi to run. Or if 20% is calculated in the equation, then the car would actually be getting 200 Wh/mi.

https://www.fueleconomy.gov/feg/pdfs/EPA test procedure for EVs-PHEVs-7-5-2012.pdf

EPA numbers on the window sticker (290 Wh/m) are based on electricity to fill the battery / miles. So, no it doesn't suggest the Wh/mile should be 20% higher than it is.

 

[Ejl80]

Ok, I have to question how y'all are driving. I'm in New England, and I commute from NH to Boston. I did 100 miles today round trip for my commute and my car read 195Wh/mi for the trip. Ambient temp was 30F in the morning and 52F in the afternoon. I had the windows cracked on the way home because it was actually hot in the cabin from the sun. Most of my commute is on I-93, half of which is at 65-70mph and the other half in traffic. I rely on EAP heavily for this stretch.

My efficiency number is only going to drop as the weather outside warms up more. Today, I was still regen limited at the start. In May, this commute will drop to around 165Wh/mi.

These are readings from the car and doesn't factor charging losses. But I can't imagine how people are over 300Wh/mi. Are you flooring it at every light and going 90mph on the highway? Even my S is slightly below 300Wh/mi this time of year.

]

Not everyone's commute is mostly highway. Mine is about 20 miles, mostly stop and go, with a dash of highway. Also, shorter trips have worse fuel economy since more fo the trip is spent with cold batteries/engines for ICE and you have to warm up the cabin instead of just keep it warm for a larger percentage of the journey. In some parts fo the country driving 65 would get you run off the road haha. And... like others have mentioned... Sticky tires.

 

[Dana1]

Really? Oof. Yeah, I've had the car since the week before Christmas, so it's been cold since I've had the car (average temp since I've had it is definitely below freezing). I think last I looked my lifetime average was about 270 Wh/mi.

Maybe I drive more grandmotherly than you?

I’m 232, lol

 

[ewoodrick]

This is incorrect. The EPA Wh/mi numbers are based on the EPA test procedure (which is conducted by the manufacturer). The LR gets 270Wh/mi, the AWD gets 290Wh/mi, it's right on the window sticker. You're thinking of the range number which is allowed to be downgraded by the manufacturer .

My mistake, but looking around at some Monroney stickers, I have seen both 26 and 27 for the LR RWD. and since they are listed as 27 kWh/100 miles, we would assume that the real number would be between 265 and 274 Wh/mi. And yes, there does seem to be some losses built in, but only about 7% (270-250)/270, not 20%.

I offer 250 Wh/mi as the consumption to hit the 310 range, since I've seen it in the energy graphs and seen the driving numbers match it.
But that doesn't answer the actual battery size, which I'm pretty sure isn't known to be a specific answer, lots of speculation. Initial EPA filings indicated 80.5 kWh, some other suggestion from Tesla at 78 kWh, and Elon mentioning 75 kWh.

In my book, moral of story.

• Battery capacities vary between batteries, definitely between battery packs.
• Tesla really hasn't said what the exact number is, for a couple of reasons, including the fact that they vary. also because they possibly have some buffers built in, and also because it's the range that is specified.
• Stop worrying about the battery. Did you care about every ounce of gas that you used? Enjoy the car, get over the battery anxiety.

 

[nvx1977]

I probably pass you on the highway often! Can I ask where in NH you are; seen you frequent the forum and think I've passed you on the highway, back when you were one of the few 3s in NE! I live in Boston and commute all over NE for clients (see my last post).

But my lifetime is 330 Wh/mi. Today was 340 Wh/mi. Driving in the exact same temps as you, with warm battery to start.....

If you ever see an ≡ badged Midnight Silver Model 3, that's me.

Still having a hard time understanding why under exact weather conditions and very similar highway conditions, that our efficiencies are so far apart.....

 

[Ejl80]

If you ever see an ≡ badged Midnight Silver Model 3, that's me.


Still having a hard time understanding why under exact weather conditions and very similar highway conditions, that our efficiencies are so far apart.....

Tires, wheels, use of heat, changes in elevation, acceleration techniques, speed traveled, and ability to use regenerative braking would be my guesses.

 

[BobAbooey]

LOL. I got a sticker, it just wasn't stuck.

When my car was delivered my sticker (the standard one which I'm pretty sure every new car sold in the U.S. is required by law to come with?) was sitting, unpeeled from its adhesive backing, on the area behind the rear seats under the rear window. It included all the standard sticker info, including options, pricing, EPA mileage info, gov't safety ratings, location of origin, etc.

I seriously thought Tesla’s did not come with window stickers I have never seen a photo of one

 

[lukex4]

You can check the real range of all Tesla models here: Tesla Range Table - Teslike.com

 

[nvx1977]

interesting... all the 19" configs (and the 20") are getting hit hard.

 

[Twiglett]

Not sure I’ve seen anything from Tesla saying it is 75k

 

[3laine]

IMHO the EPA numbers should be much worse than they are since they do not account for idle drain, vampire drain, or climate control.

Technically, the EPA test procedure accounts for some vampire drain as the procedure is to charge the car fully and then leave it overnight and do the test the next day.

But I agree with your point. In real life, people may experience 5-10+ days worth of vampire drain per equivalent full charge, not just 1 day's worth.

As a result, my i3 is actually more efficient than my Model 3. Both cars use 4-5 kWh per day on my commute, but the Model 3 also loses ~1kWh/day to vampire drain and the i3 loses almost none.

Not a big deal, but bolsters your point that EPA numbers mostly ignore vampire drain, so they significantly underestimate Model 3 electric usage.

 

[Daniel in SD]

Technically, the EPA test procedure accounts for some vampire drain as the procedure is to charge the car fully and then leave it overnight and do the test the next day.

Interesting! Didn’t know that. It annoys me that it lists the cost per year assuming 15k of driving but doesn’t include the real vampire drain for that mileage. It would be interesting to know the true energy consumption of the fleet. I’m sure Tesla has the numbers given that all our cars are very connected.

 

[Watts_Up]

Don't EPA also include Regenerative braking?

See video at 8:03

 

[AlanSubie4Life]

And yes, there does seem to be some losses built in, but only about 7% (270-250)/270, not 20%.

I encourage you to check this number yourself if you don’t believe the 10-12%. In the end it may make some assumptions about battery size, if you are not doing the test over a short interval (because...vampire...)
For anyone interested in actually measuring it, it’s not that complicated:

1) charge to a certain percentage/ rated miles
2) immediately drive a significant distance (100 miles would be fine). Do not use preheat and do not spend any time in park.
3) immediately charge the car up again to the same % and miles at a location where you can meter the kWh added, preferably at the same temperature as step 1) (use a Chargepoint, or a separate meter at your house if you have one). Do not use a Supercharger - they will have significantly better efficiency due to lack of conversion losses - and I don’t know actually, but Tesla may only meter energy actually delivered to the battery at SuChrgs (seems likely). (Means maybe you can discount Supercharger prices by perhaps 10% when comparing them to home charging costs...more bang per kWh)

Then take kWh added and divide by miles driven.

If you want, you can compare to the in-car meter for your trip

If you don’t do this test all in one shot (leave it overnight, do multiple drives, etc.) it is significantly more complicated to actually determine the charging efficiency (though you can still calculate your true wall-to-wheel Wh/mi). In the end, calculating the charging efficiency always depends on the accuracy of the in-car meter, and there are several issues with that:
1) it doesn’t count a lot of use. None while in park, specifically.
2) it may not be exactly accurate - I have noted that it seems to read a few % low, but this is with the assumption of 75kWh being available - which may not be the case.

So you really have to do the charging efficiency experiment carefully in one shot. I’ve done it before and I end up with charging efficiency around 88-90%. So 10-12% losses. You can check for yourself if desired.

 

[AlanSubie4Life]

Ok, I have to question how y'all are driving. I'm in New England, and I commute from NH to Boston. I did 100 miles today round trip for my commute and my car read 195Wh/mi for the trip. Ambient temp was 30F in the morning and 52F in the afternoon. I had the windows cracked on the way home because it was actually hot in the cabin from the sun. Most of my commute is on I-93, half of which is at 65-70mph and the other half in traffic. I rely on EAP heavily for this stretch.

My efficiency number is only going to drop as the weather outside warms up more. Today, I was still regen limited at the start. In May, this commute will drop to around 165Wh/mi.

These are readings from the car and doesn't factor charging losses. But I can't imagine how people are over 300Wh/mi. Are you flooring it at every light and going 90mph on the highway? Even my S is slightly below 300Wh/mi this time of year.

-edit-
grabbed a photo:

View attachment 393000

This is an excellent result. The RWD is fantastically efficient. In decently heavy traffic, all the cars will fare quite well though.

I have a P3D+, so it’s kind of a different ball game. Lifetime is 290Wh/mi. But for trips at average speed of 45mph I can get 260Wh/mi, and for steady freeway speed (80-85mph on freeway, average speed for trip 60mph)), I seem to get 330-340Wh/mi.

Yes I floor it fairly frequently, but not from every stop. I rarely use the brakes. I know how to drive efficiently, but whether I do depends on my mood.

Would be cool to know your walls-to-wheel result, but it is pretty annoying to do so, or even impossible to determine.

 

[3laine]

Interesting! Didn’t know that. It annoys me that it lists the cost per year assuming 15k of driving but doesn’t include the real vampire drain for that mileage. It would be interesting to know the true energy consumption of the fleet. I’m sure Tesla has the numbers given that all our cars are very connected.

Yeah, that would be very interesting! However, since it would definitely be lower than the EPA rating due to daily vampire drain (rather than just one day of vampire drain per full battery) and people who like to take advantage of the car's performance capabilities, I'm sure they'll never share that info.

It would take way too much effort, but it would also be interesting for the EPA to test using the average daily mileage. Charge the car up, then drive it just ~30 miles/day until the range is exhausted.

 

[Colgate2004]

Funny hearing everybody's (wildly divergent ) efficiency numbers... yeah, I'm hoping to get my 270 average right now (based on *only* winter driving) down substantially this summer.

(FWIW, I drive almost exclusively on the highway, and I always have the TACC set at 79mph. But I almost never use the heater, seat heaters, A/C, etc., and I've made a point since I got my driver's license as a kid to learn how to drive as efficiently as possible. I pretty much never use the brakes even when regen is basically off due to the cold. )

I'm planning to leave one of the tripometers going forever to get a true lifetime average. Now that it's warming up though maybe I'll reset one of the other ones to start to get a non-winter measure. I wonder how low I'll be able to get it to go?