Lifetime Average Wh/mi

[Brass Guy]

In a charge cycle for example, my car's battery depleted from 90% to 21% after driving 141.5 miles and the car's computer indicated that 50.2 kWh had been used, with an average 355 Wh/mi. Now the calculation is correct by doing the math 50,200/141.5, but in reality, my depletion dropped by 69% or 69kWh of a 100kWh battery!

Was the 141.5 miles driven in one driving session? The 50.2 kwh used shown on the display does not include energy consumed while not driving; such as so called vampire losses, Keep Climate On, Cabin Overheat Protection, etc.

 

[T100d-]

 

[T100d-]

This photo was taken after the car has been charged to 90% a few days earlier. During this cycle, i was very careful to go light on accelerator, almost no AC, no wakeup with the app, and trying to extract much mileage. But i did drive 80mph on highway. Imho, parasitic or vampire loses should be included in energy used 'since last charge' because I'm reality that energy was actually used

 

[Brass Guy]

The number listed under "Since last charge" does not count energy losses. It's really "energy used while driving" since last charge.

Everybody loses at least 2 miles per day (say 1%?), some lose more than 10 (3% to 4%?); just from the car sitting. None of that energy is included in the 50.2 kwh shown in your picture.
Also if you used the phone app to pre-cool (or heat) the cabin, that energy is not included.

 

[wdolson]

This didn't involve a supercharger. My battery level went from 90% to 21% of a 100kWh capacity, so that's where i got the 69 kWh. If i were to recharge my battery from 21% to 90%, one might think that my wall charger will supply 69 kWh of energy (barring loses in the wall charger and in the wire from my electrical panel)

So much for my theory.

Something is off with your car. For a P100D of your vintage, 100 KWH battery and 325 miles of range, you should be seeing about 308 Wh/Mi if you're getting the EPA range. 355 is a bit high for EPA rating, but if you have different tires that can cause more energy usage. There is also a learning effect, as I said I thought I was pretty efficient when I bought the car, but I've become more efficient over time.

I've found the instruments to be a little off, but no more than 5-10% and how much it's off varies depending on conditions. Jason Hughes who has published a lot of information he's gleaned from taking apart Tesla's and examining the firmware has said that the energy calculations are not linear. On short trips the MCU fudges the numbers a bit but on longer trips the numbers should be accurate.

 

[T100d-]

Was the 141.5 miles driven in one driving session? The 50.2 kwh used shown on the display does not include energy consumed while not driving; such as so called vampire losses, Keep Climate On, Cabin Overheat Protection, et

 

[T100d-]

The miles were driven in a couple of days, and no preconditioning or remote access during that time. AC (climate) was in completely off position, and i did not race anyone at all. I have a suspicion that maybe i have a dragging brake pad that might explain the high energy usage per mile. But my argument is that approx 19kWh were lost in a couple of days, and vampire/parasitic loses I'm sure didn't account for that much energy.

Even if the battery is 100kWh, and only part of it is reserved for locomotion (akin to a Windows pc with advertised memory, but the operating system occupies a portion) the energy not accounted for is very significant and I'm reality i used 488 w/mi. Now that's alarming!

 

[WhiteWi]

If it was in couple of days your whole calculation is wrong. Also your average efficiency very high. My 2016 S 75 average is 276

 

[T100d-]

I've taken three long road trips in five years. I've found the range used per leg to be very close to what is reported. Less than 10% inaccuracy. How are you measuring the real energy you claim the car used? If you are going by how much energy the car took on at the supercharger, it may be you got a supercharger with a problem and there was high resistance loss while supercharging. ie your car actually took on about 50 KWH of energy while supercharging, but the supercharger put out 69 KWH and 19 was lost in the equipment. That is a problem with that one supercharger and not a problem with your car or anything endemic to supercharging.

Tesla is better with their superchargers now, but back in 2016 I spoke with a tech at a supercharger when I had problems with slow charge rates on my trip. He said they were having problems with superchargers aging too quickly and he spent most of his time replacing parts that were wearing out from excessive heat. As they broke down, one of the failure modes was they tended to develop higher electrical resistance, the cables and handles would get very hot (I ran into this) because of resistive heating.

Every model of Tesla needs to go through EPA testing where they put the car through a standardized testing regime. Other countries have their own testing regime for determining real gas mileage/range. Most manufacturers base their range/gas mileage claims on the results from the testing agency. Occasionally a car maker may sandbag and claim less range or poorer gas mileage than the tests, which I believe has been the case with some EVs. However I believe there are laws against claiming more than the testing agency reports.

Most cars sold in both Europe and the US have better claimed range/gas mileage in Europe because the European agency's tests are not as close to real world conditions as the EPA and they come up with better numbers. In most cases the difference is around 20% if I remember right, though I know it differs from car to car.

On the highway EVs tend to do worse than their EPA rating because the EPA test focuses more on how people tend to drive in cities than on highways and EVs get their worst efficiency when driving at high speeds, whereas ICE tend to get their worst efficiencies in stop and go traffic (than regen for that).

I have read the criteria of the EPA test and for EVs they take into account the losses while charging the car (though they only charge the cars on AC), so they look at how much energy the car drew from the power mains, not how much went into the battery.

AC charging and DC charging do have different losses. If you charged a Tesla at the same rate as you do with AC charging, it would be more efficient than AC because the electricity goes directly into the battery and bypasses the AC charging equipment which has some losses (though the latest generations of AC chargers are way up in the 90%s for efficiency). DC charging has losses from electrical resistance anywhere along the line. Supercharger cables are thicker than AC charging cables in an attempt to keep I^2R losses down.

Copper has the lowest resistance of anything we know of in the temperature range we humans live in. There are superconductors that have zero resistance, but the best superconductors quit working above the temperature of liquid nitrogen. Kind of useless for everyday uses. So we use a lot of copper for electrical uses. Copper still has resistance though and it mounts up when you put a lot of current through it, the power loss goes up with the square of the current.

Batteries also get hot when you charge them fast due to their own internal resistances. If you've hung around a Tesla while supercharging the cooling fans and coolant pumps start going nuts after about 10-15 minutes because they are pumping coolant through the battery pack to cool the batteries.

Relatively low power DC charging is very efficient, but at the sorts of powers you draw from a supercharger, there are losses. Though losing 19 KWH to get 50 is excessively high and tells me that something was probably wrong with the individual supercharger you used.

I have free supercharging, so I've never had any indication how much energy was used to put energy in my battery pack. I would not be surprised to see 5-10% equipment loss while supercharging, but over 30 tells me something was wrong with the charger. I would try and contact Tesla because you were overcharged for their faulty equipment.



I thought I was a pretty efficient driver when I got my car. The first year my Wh/Mi was around 320, but since my MCU upgrade it's under 270 (it bounces around in the high 260s).

wdolson, thank you for the detailed response. I'm guessing you're an engineer. I'm an electrical engineer, and understand I^2R loses, and truthfully no one really calculates the voltage drop from their electrical panel. I use 50' of 6awg and drop about 5 volts at 48 amps, so there's another 240w of loss in the charging. For 6+ hours that's about 1.5kWh of wasted energy per charge. Not a big deal, but reality is reality. My question is that the car depletes more energy that the instruments indicate, and that's where my dilemma comes in. Is this related to internal resistive loses within the cells themselves, or there's energy being used without the energy management system being aware. A lead acid battery will discharge sitting on a shelf due to it's internal loses. Wondering if i have a case of this nature. Regardless, is a pleasure chatting with you, and I'll do some more analysis to see if this issue pertains to my car exclusively, or if it's common to all/most owners. Best regards

 

[T100d-]

If it was in couple of days your whole calculation is wrong. Also your average efficiency very high. My 2016 S 75 average is 276

Wrong? Not sure how my calculation is wrong. The car depleted the battery from 90% to 21%, so that's 69% difference. 69% of a 100kWh battery is 69kWh. The energy management system indicated 50.2kWh for a discrepancy of 18.8kWh. Now i don't think that this energy is due to vampire loses

 

[wdolson]

wdolson, thank you for the detailed response. I'm guessing you're an engineer. I'm an electrical engineer, and understand I^2R loses, and truthfully no one really calculates the voltage drop from their electrical panel. I use 50' of 6awg and drop about 5 volts at 48 amps, so there's another 240w of loss in the charging. For 6+ hours that's about 1.5kWh of wasted energy per charge. Not a big deal, but reality is reality. My question is that the car depletes more energy that the instruments indicate, and that's where my dilemma comes in. Is this related to internal resistive loses within the cells themselves, or there's energy being used without the energy management system being aware. A lead acid battery will discharge sitting on a shelf due to it's internal loses. Wondering if i have a case of this nature. Regardless, is a pleasure chatting with you, and I'll do some more analysis to see if this issue pertains to my car exclusively, or if it's common to all/most owners. Best regards

Yes, I have a degree in Electronic Engineering.

It looks like you discharged the car over a few days. The reported electricity used since the last charge only accounts for the energy used while the car is "on" (in driving mode). When the car is unplugged and sitting, it consumes energy, but that isn't counted in the energy used. I display estimated range remaining instead of percent and I've found when I'm running errands that the car can lost a few miles of range if it sits in a parking lot for an hour or so. It's always done this and it's more common in warm weather. I haven't noticed a difference since they introduced cabin overheat protection, so I don't think it's that. I suspect when the batteries are a little warm the coolant system runs on low for a while after you park to cool the batteries back down to ambient temperature.

Healthy li-ion cells should have very low internal resistance. They have some, but it's among the lowest of all battery types. I believe non-rechargable lithium batteries are the only type that have lower internal resistance.

 

[T100d-]

Thanks for your reply. Admittedly, the 'vampire' loses are indeed there, but in the experiment i posted, i had approx 19kWh of energy discrepancy in a couple of days. Granted that there is cooling of the cells, but i purposely did this in the spring (Connecticut) so that ambient temps are not too much of a factor. 19kWh is a lot of energy. That's about the amount of energy used to move my ~2.5 ton car 50 miles! I seriously doubt that these communication, cooling, parasitic loses should amount to that level. I have requested to speak to an engineer at Tesla, but it's not allowed... I'd like a conversation engineer to engineer, so that it may be technically explained how a 'comprehensive test' on my battery and car, according to service, resulted with no issues. Regards

If it was in couple of days your whole calculation is wrong. Also your average efficiency very high. My 2016 S 75 average is 276

I think mine might have a bit more loses, since it contains performance motors front and back. But regardless, the factory claimed usage is 100,000Wh/315mi= 318Wh/mi. Which seems logical. In reality, i consume 69000Wh/141.5mi=488Wh/mi! Even if I'm off a bit, this value is absurd

 

[nvilletele]

I haven't gone through the entire 108 pages of this thread, but I would be curious to hear what sort of Wh/m do people who live in extremely flat areas get.

When I am driving straight on flat roads, it seems there is really little power usage. Of course, living in San Diego, one cannot go very far on flat roads. Lots of hills and canyons and so forth.

 

[Snerruc]

I live in Florida, which is pretty flat. My Raven is averaging 267 watts/ mi for 24000 miles of mixed driving. I usually drive 5 over the limit. Around town I’m in the 240s. On the road about 80% of rated unless I have a strong head or tail wind. Thats at 75 mph.

 

[BioSci]

I live in New England, near Boston. I've had my MS for 9 months now. At 5821 miles on the odometer, the lifetime average is 277 wh /mi. This includes driving in the winter, with typical New England winter temperatures.

I just completed my first cross-country drive in this car. Driving mostly at highway speeds over mostly level ground with average temperatures around 85F running the A/C all the time, I averaged 266 wh/mi. This comes acceptably close (within 6%) to the promised 250 wh/mi. When I drive around town at suburban speeds during warm weather, I usually get about 220 wh/mi, and that's on fairly hilly terrain.

 

[Jasper7821]

I bought a 2014 P85+ 21" rims 90k miles two months ago. 90% city driving. After a few thousand miles, I'm averaging 328 wh/mi

 

[SeminoleFSU]

I haven't gone through the entire 108 pages of this thread, but I would be curious to hear what sort of Wh/m do people who live in extremely flat areas get.

When I am driving straight on flat roads, it seems there is really little power usage. Of course, living in San Diego, one cannot go very far on flat roads. Lots of hills and canyons and so forth.

This will depend on a lot of things. How fast do you drive? What's temp outside? what's the cabin temp set to? Do you use seat and steering wheel heaters over cabin heat in cold climates? What year is the vehicle? Tesla made constant improvements making cars more efficient over time. What size is your battery? Larger batteries weigh more and are less efficient. What size tire are you running? Stock wheels or aftermarket? Do you have aux equipment running like a dashcam? Regen turned to standard or low? On and on.
I've owned two model S's a 2013 P85 and now a 2018 100D. The 100D is slightly more efficient because of 19" vs 21" wheels and probably slightly more efficient motors. I avg 325Wh/Mile mostly highway driving 70-75ish MPH

 

[Hayseed_MS]

I am now at approx. 15k miles (refresh LR with 21" wheels). Drive spirited but not very aggressive - more defensive than offensive. Mostly flat midwest driving but have logged a couple thousand miles through hills in KY, TN, WV, NC, and SC. Probably 70% highway driving 70-75mph. Temps as high as 105F down to 40F. Average is in the 70-80F range. Use HVAC at whatever makes me comfy. I drive it like I do any vehicle - ICE or EV.

According to my trip comp - my overall average is 291wh/mile.

 

[aerodyne]

I am now at approx. 15k miles (refresh LR with 21" wheels). Drive spirited but not very aggressive - more defensive than offensive. Mostly flat midwest driving but have logged a couple thousand miles through hills in KY, TN, WV, NC, and SC. Probably 70% highway driving 70-75mph. Temps as high as 105F down to 40F. Average is in the 70-80F range. Use HVAC at whatever makes me comfy. I drive it like I do any vehicle - ICE or EV.

According to my trip comp - my overall average is 291wh/mile.

Sounds good...I drive conservatively under 75, and I am getting 277 YTD on my 85D with EPA rated consumption of 290...

Good to have a data point and I am planning to upgrade to LR.

 

[VM0412]

I am now at approx. 15k miles (refresh LR with 21" wheels). Drive spirited but not very aggressive - more defensive than offensive. Mostly flat midwest driving but have logged a couple thousand miles through hills in KY, TN, WV, NC, and SC. Probably 70% highway driving 70-75mph. Temps as high as 105F down to 40F. Average is in the 70-80F range. Use HVAC at whatever makes me comfy. I drive it like I do any vehicle - ICE or EV.

According to my trip comp - my overall average is 291wh/mile.

@Hayseed_MS what is your estimated 100% charge in miles on any given day (range over several days)?

I’ve heard it’s normal for there to be a 5% drop in the first 6k miles