Surprising Impact to Range

[TW14 9LF]

Yesterday we went from our home in the San Gabriel Valley (Los Angeles) to Edwards Air Force Base to attend the open house / air show. According to Google, it was 113 miles one way. So, figured my 2018 Long Range RWD would make it there and back without much trouble. So, the morning before, I made sure to top up the battery to 100% (I typically only charge to 80%). My first surprise was that we only had 47% remaining when we arrived at Edwards. When we were ready to come home and I plugged in my address, the car told me I wasn't going to make it without recharging. I really expected that I would be able to make this round-trip without having to recharge. Good news was, there was a 250 kw charger in Hesperia, only about a mile off of my route. We arrived at that charger with 11% remaining. 10 minutes (and $10) and we were on our way again. Actually worked out well, as my wife needed me to stop so that she could go to the restroom, so we would have stopped anyway.

My reason for posting this is to point out that, even though you have a EV that has a 300 mile range (my car still shows 300+ miles range, even after 37,000+ miles), you won't get that mileage for a "real" trip. My normal driving of this car is me only, and my normal route is pretty flat. Since I've owned the car, I've averaged 243 kw-hr / mile. On this trip, that increased to 380+!!! Why? Well, there were four adults in the car, plus lawn chairs, a small cooler, and a few other things. To get to Edwards AFB, you have to go over the Cajon Pass, which is a bit over 4000 ft elevation. I drove at 75 mph, with the A/C on. So I knew I wouldn't get 250 kw-hr/mi, but I didn't expect a drop to 380!

Details of my car....2018 LR RWD, 18" wheels, no aero covers, Michelin Pilot Sport A/S tires, 37,000+ miles.

Good part of this trip? The airshow was AWESOME!!! I got to drive my car on Rogers Dry Lake Bed, which was kind of cool. And I was once again reminded of why Tesla is so far ahead of the rest with respect to EVs; being able to find a high speed charging station almost anywhere, and know that it will be operational is key to owning an electric car. Down side.....took me nearly 3 hours to clean the car, that dust went literally everywhere. Didn't help that we ran into a rain shower on the way home, made the car even more of a mess.

Thanks for reading.

Keith

 

[jjrandorin]

I am a bit confused about what the "surprising impact to range" was. Are you saying that its surprising that you got less range because you had the car loaded up with 4 adults and stuff (and drove over some elavation) vs when you drive alone?

 

[Tronguy]

I am a bit confused about what the "surprising impact to range" was. Are you saying that its surprising that you got less range because you had the car loaded up with 4 adults and stuff (and drove over some elavation) vs when you drive alone?

Yah. That. But, I'm betting our man did 70+ mph the whole way there and back.

I'm in NJ. There's sections of the Garden State Parkway down near the southern part of the state where, based upon experience, the minimum speed is 70 mph and people go much faster. But most of the state is far too congested for that kind of thing, unless one has a death wish. As a result (and I'm not a crazy driver), I really do get that 250 W-hr/mile range on my 2018 M3 LR; sometimes less, sometimes more.

I've driven around CA. When the roads open up, so do the drivers . To the OP: Just how fast were you going, sir?

 

[3sr+buyer]

Yah. That. But, I'm betting our man did 70+ mph the whole way there and back.

Yes, the first post says that they drove 75mph with the AC on (didn't say what the outside temperature was like).

 

[3sr+buyer]

Not sure if it is a big surprise that economy is much worse than rated when the following are true:

• Driving at 75mph.
• Going up significant elevation.
• No aero covers on the 18" wheels.
• Tires are probably not a LRR or T0/T1 version.
• Fully loaded with passengers and cargo.
• AC on (what outside temperature?).

 

[Tam]

...you won't get that mileage for a "real" trip...

That's no secret. I expected it. Nevertheless, when it first happened to me in 2012 with my Model S, it's still quite a shock.

Some don't think EVs need more range but I take that any day.

 

[TW14 9LF]

I knew I was going to take a range hit, but I really did expect to make a 226 mile round trip without charging. I expected to get home with about 10% charge remaining....not have to recharge 50 miles short of home. So that's the surprising part.

Yep, was going 75 on I-15, a bit slower on Hwy 395 (due to traffic). BTW temp outside was mid 60s until we got to the desert, then high 70s, low 80s. So, nothing extreme.

Keith

 

[Tam]

...expect...

Now that I experienced the reality in 2012, I won't leave until I have 100 extra miles for the next stop.

For example, if my next stop is 226, I won't leave until my battery gauge says 326.

However, you stop in between so my 326 won't work for my practice.

That means for the next stop at 113 miles away in Edwards Air Base, I won't leave until I got 213 on my battery gauge.

From Edwards AB, I will make sure I got 213 on the gauge just for the 113 mile trip home.

You just need to figure out what numbers work for you so you won't be surprised.

 

[AlanSubie4Life]

I knew I was going to take a range hit, but I really did expect to make a 226 mile round trip without charging. I expected to get home with about 10% charge remaining....not have to recharge 50 miles short of home. So that's the surprising part.

Yep, was going 75 on I-15, a bit slower on Hwy 395 (due to traffic). BTW temp outside was mid 60s until we got to the desert, then high 70s, low 80s. So, nothing extreme.

Keith

Seems like you should have made it, with 47% on arrival with the uphill (perhaps 1500 feet net). Barring unusual tailwinds/headwinds. What was your departure % from Edwards? (Would definitely have needed to turn off Sentry!)

With the aero covers and high inflation pressures (you did not mention what you run, ~40-45psi would be good) you would likely have made it (would probably have been tight)!

Arriving in Hesperia (3100’) at 11% (>33 rated miles) with all that downhill (7 rated miles per thousand feet - with your heavy load you might have got 8 - I assume you live at around 800'-1000' in San Gabriel Valley)…might have been able to make it another 50 miles…though definitely the right call, and you probably would not have (you certainly would have pushed into the buffer and might have been pushing the car). It's a good spot other than the length of the walk to Target, and Chop Stop has good bowls.

Anyway yeah it’s a stretch but with a bit of drafting and other measures on this specific trip I think it is possible.

Fortunately Superchargers are plentiful, and as long as they are not full (a problem on that route on Fridays and Sundays and even Saturdays get busy), it is good.

Tesla needs many more Superchargers.

I haven’t found that having a heavy load in the car significantly impacts range. Not sure exactly how much it matters… has some impact on rolling resistance but not sure exactly how to work that out. Has no effect on aero, and elevation doesn’t matter - as long as it nets to zero.

On this trip, that increased to 380+!!!

Something doesn't add up here. If this was the top of the pass, it probably makes sense (I think it is the only thing that makes sense). But I assumed you meant on arrival at Edwards.

Anyway 380Wh/mi * 113 miles = 43kWh, and 43kWh / (0.955*76kWh/325rmi) = 192rmi (best case 59% of your battery if it had no capacity loss). So that doesn't work; you used 53%.

Anyway about 320Wh/mi seems more likely for arrival at Edwards. 71kWh battery, this would use about 53% of it (0.53*71kWh*0.955/113mi = 318Wh/mi). The net elevation gain of ~1300 feet would have added 20Wh/mi, so the elevation-corrected 300Wh/mi is still a bit high.

Pomona to Cajon Pass is 35miles and 2700 feet gain so that would add 4.6kWh, meaning 130Wh/mi, so 380Wh/mi very conceivable at that point, but not really reflective of poor efficiency (elevation corrected would be 250Wh/mi).

 

[oreobbq]

Fortunately Superchargers are plentiful, and as long as they are not full (a problem on that route on Fridays and Sundays and even Saturdays get busy), it is good.

Tesla needs many more Superchargers.

I'd rather poop my pants or get stung by a hornet than wait in line to charge at a supercharger.

 

[TW14 9LF]

Seems like you should have made it, with 47% on arrival with the uphill (perhaps 1500 feet net). Barring unusual tailwinds/headwinds. What was your departure % from Edwards? (Would definitely have needed to turn off Sentry!)

With the aero covers and high inflation pressures (you did not mention what you run, ~40-45psi would be good) you would likely have made it (would probably have been tight)!

Arriving in Hesperia (3100’) at 11% (>33 rated miles) with all that downhill (7 rated miles per thousand feet - with your heavy load you might have got 8 - I assume you live at around 800'-1000' in San Gabriel Valley)…might have been able to make it another 50 miles…though definitely the right call, and you probably would not have (you certainly would have pushed into the buffer and might have been pushing the car). It's a good spot other than the length of the walk to Target, and Chop Stop has good bowls.

Anyway yeah it’s a stretch but with a bit of drafting and other measures on this specific trip I think it is possible.

Fortunately Superchargers are plentiful, and as long as they are not full (a problem on that route on Fridays and Sundays and even Saturdays get busy), it is good.

Tesla needs many more Superchargers.

I haven’t found that having a heavy load in the car significantly impacts range. Not sure exactly how much it matters… has some impact on rolling resistance but not sure exactly how to work that out. Has no effect on aero, and elevation doesn’t matter - as long as it nets to zero.


Something doesn't add up here. If this was the top of the pass, it probably makes sense (I think it is the only thing that makes sense). But I assumed you meant on arrival at Edwards.

Anyway 380Wh/mi * 113 miles = 43kWh, and 43kWh / (0.955*76kWh/325rmi) = 192rmi (best case 59% of your battery if it had no capacity loss). So that doesn't work; you used 53%.

Anyway about 320Wh/mi seems more likely for arrival at Edwards. 71kWh battery, this would use about 53% of it (0.53*71kWh*0.955/113mi = 318Wh/mi). The net elevation gain of ~1300 feet would have added 20Wh/mi, so the elevation-corrected 300Wh/mi is still a bit high.

Pomona to Cajon Pass is 35miles and 2700 feet gain so that would add 4.6kWh, meaning 130Wh/mi, so 380Wh/mi very conceivable at that point, but not really reflective of poor efficiency (elevation corrected would be 250Wh/mi).

Appreciate the analysis, this is really good. The 380 was when we were about to go through the gate at Edwards, and I noticed we were at about 47%. Going home, the downhill really made a difference, we actually got under 200 whr/mi (186 if I remember correctly). Whatever the case, made it fine, thanks to the Supercharger network. It wasn't busy at all, even at 5:00 PM on a Saturday, only about 8 or 10 other cars there, so was able to drive right up and plug in. Was funny, we added enough charge in less time than it took my wife to walk across the parking lot to use the facilities in Target; she was surprised when I picked her up at the door!!

BTW, hope nobody is taking this post as anything negative. Just wasn't expecting that type of range reduction for this trip. I truly thought this was a reasonable expectation to be able to make this trip without a recharge, and was surprised when I wasn't able to. Will definitely take that into consideration the next time we do a fully loaded longer trip. Meanwhile, back to my solo 86 mile round trip work commute, and my 243 wh/mi average.

And, I'll say it again....the airshow was really amazing, definitely worth the drive out there and back.

Keith

 

[AlanSubie4Life]

The 380 was when we were about to go through the gate at Edwards

Did you take a picture (just so recall cannot be an issue)? Really can’t make sense of that since it means 43kWh, so 47% remaining would not make sense. Either it 1) Wasn’t 380Wh/mi 2) Was for a shorter segment (not since last charge), or 3) something else I can’t think of.

Worst case would be brand new battery, 345Wh/mi, arrive 47%.

Anyway it doesn’t matter.

 

[KenC]

ABRP says a 2018LR, you could go over Cajon from San Gab to Edwards and back, with 800lbs extra weight at 113% of speed limit and your efficiency for the trip would be 307Wh/mile. Not sure why your numbers were so much worse.

 

[3sr+buyer]

ABRP says a 2018LR, you could go over Cajon from San Gab to Edwards and back, with 800lbs extra weight at 113% of speed limit and your efficiency for the trip would be 307Wh/mile. Not sure why your numbers were so much worse.

Higher rolling resistance tires and no aero covers on the wheels?

 

[dfwatt]

I knew I was going to take a range hit, but I really did expect to make a 226 mile round trip without charging. I expected to get home with about 10% charge remaining....not have to recharge 50 miles short of home. So that's the surprising part.

Yep, was going 75 on I-15, a bit slower on Hwy 395 (due to traffic). BTW temp outside was mid 60s until we got to the desert, then high 70s, low 80s. So, nothing extreme.

Keith

If you're concerned enough about range to post then you should definitely put your aero covers back on the wheels. They make a big difference especially at highway speeds

 

[AlanSubie4Life]

Not sure why your numbers were so much worse.

Partly for the reasons mentioned.

But also 380Wh/mi over 113 miles is literally impossible for this vehicle, if arriving at 47%.

Assume a typical 72kWh (308 rated miles for 2018 LR RWD) remaining pack.

68.8kWh available above 0%.

53% (47% arrival charge) of that is 36.4kWh.

Over 113 miles that would be 322Wh/mi. (Actually 319Wh/mi since there is a ~1% loss factor here…)

So something in that ballpark had to be what was displayed (or maybe arrival % was not 47%). Or it was the display for just a segment of the drive. Or something.

Anyway, these calculations are nearly always perfect, so something got lost in translation here (pretty easy to misremember or whatever, without pictures; I always take pictures if I want to track, since I can’t remember anything any other way).

 

[Tronguy]

Um. 2018 M3 LR is rated at 250 W-hr/mile or a little less. With a 75 kW-hr battery, that's where 75e3/250 = 300 miles range comes from.

During the summer months and doing commuting/driving around the landscape, I really do get 250 W-hr/mile. But most of that isn't at 75 mph, it's 70, max, and local roads.

Winter time is a different story. Heat in this car isn't generated by any old heat pump, it's by an electrical heater and/or the heat coming off the motors/batteries. It's not at all unusual to get 350 W-hr/mile in January when it's 15F outside.

Range drop is simple: 300miles * 250W-hr/350W-hr = 214 miles.

And now you know why later Teslas that incorporate heat pumps get much better mileage in the cold.

Just a comment about the EPA. Everybody likes to diss the EPA on how their mileage numbers don't match up with reality. This may sound weird, but in all the years I've been driving cars around, I've always found that the EPA numbers were pretty close to reality. Admittedly, my driving's on the East Coast; we don't get 75 mph limits here. As those of a mathematical bent will tell you, air resistance goes up as the cube of velocity. And our idea of Mountains barely touches the idea of foothills out west.

Finally: If you think the EPA is 'way off, you should check out the EU entity that does mileage numbers. They overestimate things by so much it's silly. Did you know that that EU body allows manufacturers to (a) do their own testing all the time and (b) allows manufacturers to put tape over door handles and panel gaps?

 

[AlanSubie4Life]

air resistance goes up as the cube of velocity.

Power to overcome drag yes.
And Wh/mi efficiency (of the aero component) increases with the square of velocity (one way to realize this is that efficiency has units of force…or just realize you have to put out the speed-ratio-cubed increase in power for less time to travel a given distance).

2018 M3 LR is rated at 250 W-hr/mile or a little less

This is LR RWD:

234 Wh/mi rated. (Line on the energy screen should be at 239Wh/mi so that matches exactly.)

So, each displayed rated mile contains 223-224Wh. (95.5%)

With a 75 kW-hr battery, that's where 75e3/250 = 300 miles range comes from.

Started at 78kWh, 74.5kWh not including the buffer. Starting range was 325 rated miles (it did more in EPA testing and was initially sold with 310rmi), which used all 78kWh.

 

[TW14 9LF]

Partly for the reasons mentioned.

But also 380Wh/mi over 113 miles is literally impossible for this vehicle, if arriving at 47%.

Assume a typical 72kWh (308 rated miles for 2018 LR RWD) remaining pack.

68.8kWh available above 0%.

53% (47% arrival charge) of that is 36.4kWh.

Over 113 miles that would be 322Wh/mi. (Actually 319Wh/mi since there is a ~1% loss factor here…)

So something in that ballpark had to be what was displayed (or maybe arrival % was not 47%). Or it was the display for just a segment of the drive. Or something.

Anyway, these calculations are nearly always perfect, so something got lost in translation here (pretty easy to misremember or whatever, without pictures; I always take pictures if I want to track, since I can’t remember anything any other way).

I did not take a picture....should have done that. And maybe I did read the screen wrong, I am on the other side of needing reading glasses, so maybe I got the numbers wrong. But, still a bit surprised (again, not disappointed) that I had to stop for a short recharge on a 226 mile round trip.

I do track my mileage / energy usage every week. Last week, I drove 464 miles (inc the trip to Edwards), used 127 kWh, at a rate of 274 Wh/mi.

Anyway, did my normal 88 mile roundtrip to work today, a combination of 75-80 when no traffic (about 1/2 the time), and some creeping when it was stop and go. Elevation change is about 850 feet (I live at about 950, my office is right next to LAX, so probably about 50-100). I started at 81%, arrived back home at 47%. Average energy use was 242 Wh/mi, using 21 kWh of electricity. This fits right in with my lifetime useage of 243 Wh/mi.

Appreciate all of the insight and comments. Again, not unhappy by any stretch, just curious and surprised. And, no, the aero covers aren't going back on, they are way too ugly!!!

Keith

 

[Destiny1701]

So essentially when we pay $15 at the SC for say 200 miles, in reality one is getting 120-140.
Cost per mile is much higher than what we actually receive.

It’s like paying $60 for say 400 miles on an ice vehicle but receiving 250 actual.

That’s insane if you think abt it.