Extreme over predicted range!

[MidAtlanticLightningClub]

What could be causing this extreme difference in range?

How fast were you driving?

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[PreservedSwine]

I get 1.8mi/kw going 80 mph. At 70 its 2.2-2.3mi/kw. With heavier traffic, I can achieve 2.6-2.8mi/kw. I think if you keep it around 70mph aka 110-115km/hr you will see a 20% increase in range.

The air is a bit more humid in S Florida. 80 mph is 1.5mi/kw. Lucky to get 2.0 mi/kw @70

At 40-45 mph with no stoplights- over 3.0 mi/kw.

At any rate- the range is based on previous behavior. The OP averaged roughly 1.9kw/hr per mile. That's about right for a mix of 80mph and 40mph.

 

[Firn]

The air is a bit more humid in S Florida. 80 mph is 1.5mi/kw. Lucky to get 2.0 mi/kw @70

At 40-45 mph with no stoplights- over 3.0 mi/kw.

At any rate- the range is based on previous behavior. The OP averaged roughly 1.9kw/hr per mile. That's about right for a mix of 80mph and 40mph.

Yeah, 2.2 @70mph is really really good.

 

[flyct]

The air is a bit more humid in S Florida. 80 mph is 1.5mi/kw. Lucky to get 2.0 mi/kw @70

At 40-45 mph with no stoplights- over 3.0 mi/kw.

At any rate- the range is based on previous behavior. The OP averaged roughly 1.9kw/hr per mile. That's about right for a mix of 80mph and 40mph.

Tires can affect range pretty significantly. That‘s primarily why a Platinum gets 7% less EPA range compared to a Lariat ER.

i went from a 23 Lightning ER to a 24 Platinum and I can confirm I “burn” at least 7% more kWh to go from my home to my cabin. With my Lariat it would take an average of 60 kWh to replenish the trip. Now with the Platinum it takes an average of 66 kWh as logged with my Tesla Wall Connector.

This is on a 125 mile trip in flat land Florida, at 62-65 mph 98% of the time.

 

[NW Ontario Ford Lightning]

My experience with my SR Lightning:
The Guess-O-meter always goes to 384km range when I charge to 100%. It doesn't chage to any other value no matter how I have been driving it. The 384km range is exactly the claimed range.

To actually get that range from the truck on the hwy, I must drive on stock tires 108km/hr (67.5mph) or a touch under, and no zippy passing the slow pokes along the way. ie the scoreboard on the truck that tells you how your doing with acceleration/braking/speed - you need to be in the 95% + in all three scales. Gradual acceleration, re-gen braking, moderate top speed.

Elevation changes - long grades are a killer, and if you set the speed control to a steady value on these types of grades you lose some range compared with allowing the truck to drop slowly 10% of your speed as you crest the grade, and then speed back up down the other side of a hill.

I have a 320km run that I do once a month that has a lot of steep hills. I have played with setting the cruise for an entire trip, compared with using the pedal to allow slowing up a grade, and speeding up on the other side. I can gain 10% difference (ie from 27kW/100km to 30kW/100km) just by 'riding the rollercoaster effect". I have also tried letting the truck slow a bit extra up a long grade, but then speed up above my target 108km/hr speed on the down hill side, to averge my net speed and gain momentum for the next hill. This works even better, as long as I am all alone on that stretch of hwy.

Note: these Hwys I have in my area are all posted as 90km/hr (56mph) and we are 'allowed' 10mph over (16km/hr) so most people drive 105-110km/h (65mph) on these hwys. No 75mph hwy in NW Ontario area.

 

[Adventureboy]

The faster you drive, the faster the SOC will disappear per mile. Much faster. Speed will kill range faster than anything else. Our trucks push lots of wind and wind power/drag is exponential. If you drive 130kph, you need 2.2 times the power to overcome the wind resistance than driving 100kph. Wind resistance is only part of the equation, but it is the biggest factor. Add that to the brick factor, and it adds up pretty quickly for our Lightnings.

 

[Newfoundland]

Man, just went on a trip with my extended range. About 50% hwy driving. Had very light AC on. And I was only able to achieve approx 380km…

I have approx 80,000km on the truck. Two cells have been replaced.

I drive on Toyo At4’s. so obviously I’m going to lose a small percentage of range with those. But leaving the house it’s said I had 520km of range.

What could be causing this extreme difference in range?

Consider doing a test and only driving with perfect techniques for a few days and reset the trip meter 1 or 2 to track this. The people that drove my 2024 Standard range xlt for 2700 miles before I bought it, averaged 2.3 miles per KW. I average 2.7 by having a really soft foot on the pedal and not exceeding 60mph on the highway. It makes a difference if you want range and not in too much of a hurry. The guess meter for miles that the truck shows always predicts low since I drive this way. On a longer trip last week, it predicted 223 MILES range and I got the equivalent of about 260! Soft foot versus lead foot for starts and stops, and speeds on the highway make this difference almost 20% between the previous driver of this truck, and my driving.

 

[inchman254]

Air resistance is the biggest factor in range difference between the GOM at the beginning of a trip and actual usage enroute. The GOM seems to adjust range for temperature, but seems to revert to spec for other factors. That's how it can guess the ~400 km range in the winter even if you park in a warm garage. Once you're underway, it starts recalculating.

If you're not a geek, stop reading here.

I'm a bit of a geek so I made up a little spreadsheet that I made up where I can put in truck speed, wind speed, temperature, and a hill factor. (It's just a bit more detailed than the excellent table that has been posted on the forum).

One of the primary, but constant, factors is rolling resistance. In a no-wind, relatively low speed/wind scenario, rolling resistance can take up more than 1/2 of your burn. It works out to about 11 kWh/100 km (1.2 mi/kWh) regardless as to your speed. (I don't like the conversion on this one because it's a constant, but it kinda works.)

If we assume a perfect temperature of about 24c (76f) and flat terrain, no wind, 100 km/hr (~60 mph), your burn will be 28 kWh/100 km (~2.2 mi/kwh). That gives you your 520 km range.
With just a 20 km/hr (12 mi/hr) headwind (not much more than a moderate breeze... enough to extend a light flag), your range drops to 380 km. The same would apply if you increased your speed by that same 20 km/hr in a zero wind condition.

If that was a 20 km/hr tailwind, your range would have increased to 600 km. Notice you only gain 80 km in a tailwind but it costs you 120 km in a headwind.

If your total airspeed was 150 km/hr (90 mi/hr) your burn would go up to 48 kWh/100km (~1.25 mi/kWh) and your range would drop to 270 km (~160 mi).

Adding in hills or temperature off ideal also has some effect.

Of course, any of us in northern climes knows that big temperature drops makes a large difference, too. A combination of very low temps, wind and truck speed can be devastating on range.

Lifting a 7000 lb truck up 1000 ft takes just under 3 kWh, plus the normal burn for the distance. Regardless as to what some people think, you only get just over 1/2 of the energy back in regen, but you're still burning for the distance when you go downhill.

So, even if you eventually go downhill that 1000 ft on the same trip, you will still burn 1.5 kWh because of that hill. And, if it's ten 100 ft hills or one 1000 ft hill or if it is over 10 miles or 200 miles, its still the same net 1.5 kWh ... about 4 miles (6 km). Just over 1% per thousand... but it adds up if you're in hilly territory. A steep hill probably burns a bit more just due to electrical heat losses at higher power, just like high acceleration burns more. A higher speed going up a hill may create this same effect because the motor is working harder, generating more heat, but saving energy by slowing down as you approach the crest is just a factor of this and lower airspeed, IMO. If you slow down anywhere on the hill (or on flat ground for that matter), you're going to save some electrons. (Edited to correct a misunderstanding.... maintaining full speed to the top of a descent means that you would have to brake (or regen) going downhill to avoid overspeed. Even regen doesn't get everything back so there would be some benefit to this.

ABRP does take all of these factors into account when it calculates a trip, which makes it a great planner provided that conditions when planning a trip (if in advance) match the conditions on the day you drive.

 

[NW Ontario Ford Lightning]

One of the primary, but constant, factors is rolling resistance. In a no-wind, relatively low speed/wind scenario, rolling resistance can take up more than 1/2 of your burn. It works out to about 11 kWh/100 km (1.2 mi/kWh) regardless as to your speed.

I am curious about this one - the max possible range and what speed to achieve it:
I had to take 'the back road home' a week ago due to an accident blocking my main hwy. The alternate route was low speed back road, but paved, and I was wondering what the effect would be on my range - turns out driving 70km/h (45mph) resulted in 16kWh / 100km - in therory this would mean 90% SOC could travel 560km ? (but would be 8 hours of driving time).

I only had 100km trip so I am not sure if the numbers would pan out like the math suggests over a much longer trek.

 

[Newfoundland]

I am curious about this one - the max possible range and what speed to achieve it:
I had to take 'the back road home' a week ago due to an accident blocking my main hwy. The alternate route was low speed back road, but paved, and I was wondering what the effect would be on my range - turns out driving 70km/h (45mph) resulted in 16kWh / 100km - in therory this would mean 90% SOC could travel 560km ? (but would be 8 hours of driving time).

I only had 100km trip so I am not sure if the numbers would pan out like the math suggests over a much longer trek.

I've found the same in my first 2 weeks driving the truck. In the range of what you described in speed is likely a sweet spot for efficiency in mileage when considering the beginning effects of increase wind resistance at higher speeds in most vehicles.

 

[inchman254]

I am curious about this one - the max possible range and what speed to achieve it:
I had to take 'the back road home' a week ago due to an accident blocking my main hwy. The alternate route was low speed back road, but paved, and I was wondering what the effect would be on my range - turns out driving 70km/h (45mph) resulted in 16kWh / 100km - in therory this would mean 90% SOC could travel 560km ? (but would be 8 hours of driving time).

I only had 100km trip so I am not sure if the numbers would pan out like the math suggests over a much longer trek.

Interesting... my model would have predicted 19 kWh/100 at 70 so I probably need to tweak a bit. ... assuming you kept your speed constant, the variable factors are wind, hilly-ness and start-to-end elevation change. If you had a 20 km/hr tailwind, that would directly explain the difference but it's pretty hilly up there as I recall and that would hurt a bit unless the overall elevation change is downhill.

 

[NW Ontario Ford Lightning]

Interesting... my model would have predicted 19 kWh/100 at 70 so I probably need to tweak a bit. ... assuming you kept your speed constant, the variable factors are wind, hilly-ness and start-to-end elevation change. If you had a 20 km/hr tailwind, that would directly explain the difference but it's pretty hilly up there as I recall and that would hurt a bit unless the overall elevation change is downhill.

yes, actually it would have been +/- 150m /500 foot drop from start to finish, with lots of small hills during the drive. Not windy at the time.

From your model, what is the max range speed? is there a point where going slower uses more energy per 100km?

 

[Firn]

yes, actually it would have been +/- 150m /500 foot drop from start to finish, with lots of small hills during the drive. Not windy at the time.

From your model, what is the max range speed? is there a point where going slower uses more energy per 100km?

There was a website, that i now struggle to find, that averaged out its EV fleet. Iirc across their fleet the highest range was achieved at 18mph...

 

[inchman254]

yes, actually it would have been +/- 150m /500 foot drop from start to finish, with lots of small hills during the drive. Not windy at the time.

From your model, what is the max range speed? is there a point where going slower uses more energy per 100km?

So the overall elevation drop would have helped bring your results closer to my prediction by just under a kWh/100 but the hills would have hurt... and it doesn't have to be "windy". A light breeze can have an effect. At 70 km/hr (40) a 5 km/hr (3 mph) (most people would say calm) tailwind changes the predicted burn from 19.3kWh/100 km to 18.3 kWh/100 km.

As for max range speed, I have run numbers right down to 20 km/hr (12 mph) and range continues to increase, which makes sense.

But...

While I do consider temp for raw battery range, my numbers don't didn't consider accessories (including the heat pump). Accessories run per unit time, not distance, so as you slow and time increases, their negative influence on range would kick in.

An extreme example is if you were stuck in traffic going 1 km/hr (or 1 mile/hr) (units don't really matter for this paragraph). Without any accessories, your burn would be simply rolling resistance.... 11 kWh/100. But if you had the A/C on and it was burning 2 kW, your burn would now be 200 kWh/100 for the A/C plus 11 kWh/100 for the rolling resistance... 211 kWh/100. So, if you're stuck in traffic for a long time... say during a hurricane evac ... use the A/C sparingly!

Because of your question, I decided to add in a factor for use of the heat pump. It's just an initial guess based on what information I could get online about heat pump consumption. The calculation basically uses 15c (60f) as a neutral point and adds some hourly usage based on how much the temperature diverges from that. It doesn't take into account the effect of seat heating or cooling, driver focused temperature control or the effect of speed on cooling the envelope (wind chill).

At -18c (0f) the prediction is that the max range speed is at about 45km/hr (28mph) with the heat pump predicted to burn 3.3 kW. At the other end of the spectrum... at hot day at 30c (85f), the max range speed is about 35 km/hr (22 mph) with the heat pump burning 1.5 kW. This 1.5 kW seems a bit low, especially on a sunny day, but sun would be a factor on the cold side, too.

Of course, with all accessories and heat pump off, the slower you go the lower the burn would be.

 

[NW Ontario Ford Lightning]

Very interesting,
I was going the right direction to be down wind, so that may be the missing bit.

ok geek out alert - some TLDR stuff follows. and some math.

Now I want to consider two scenarios - slower and no stop, vs faster but adding a stop to charge.
We lose travel distance while sitting charging, but this is a trade off with overall time to travel a route. Let's consider a 600km trip (375 miles) in my SR:

At low speed say 50km/hr the time to go 600km is 12 hours. But 'could' be done with one charge.

At 70km/hr the 600km drops to 8.57 hours but a SR would need to stop and charge:
say 70km/hr is 19kwh/100km: this means a stop to charge is required for a SR, 6 x 19 =114kWh required from 98kWh battery - 16kWh needed.
say the driver stops part way, after 300km, to charge up the required 16kWh they will need if they started with 100%.
on a 50kW charger this is 19.2 minutes of charging, let's call it 30-minutes including time to connect and get going again. Now the 600km trip is: 600km/70 = 8.57hrs plus 1/2 hr = just over 9 hours insteadd of 12 hours.

I find my target 108km/hr runs between 28-30 kWh/100, so now considering 600km trip:
6 x 30 = 180kWh required (98 +82) to charge 82kWh using a crappy 50kWh charger is 1.64hrs of charging time. And the driving time is now 6 hours for a total trip time of 7.64 hours. better than 9hours.

We should be able to calculate an optimal speed where total trip time is minimized (charging plus driving) assuming charging facilities are available. We can refine this for the speed of the charging facility - although DCFC are not constant charging speed due to thermal effects, making the math a bit more involved.

My last trip to Winnipeg I recall going about 120km/hr, 33kWh / 100km (as best I can recall).
at 120km/hr a 600km trip is now 5hrs but will take a total of 33 x 6 = 198kWh and two stops will be needed in a SR to charge up the extra 100kWh needed. 2 hours of 50kW charger time so 7 hours for the total trip. ie 38 minutes less than the 7.64 hours that it would take at 108km/hr.

With DCFC the total trip time will be less driving faster, as long as the chargers are available along the route. cost of the trip will be more though.

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