Lifetime Average Wh/mi

[AllElect2015]

Just joined and would appreciate some insight. Received my 85 Model S about 3 months ago (2015 lease return). Since then put on 1225 miles using 400 kWh so the rate is 326 Wh/mile. I'm good with the math there. What I am trying to understand is I charged to 245 miles but when I had driven 154 miles battery said I only had 31 miles left. Usage rate since my last charge was 354 Wh/mile during this last time so a little higher than average. But the way I calculate it, if I charge to 245 miles of a 265 miles stated range for car then I am at 92% (245/265) of the battery which is 85K so I would estimate I was at 92% of 85K or 78,2K of energy to use. If I drove 154 miles at 354 Wh/mile then I used 54.5K of energy and I should have had the difference 78.2-54.5 or 23.7 K left of charge. At 354Wh/mile the 23.7K of remaining charge should have allowed me to drive another 66.9 miles not the 31 miles the car reflected. Where is the error in my logic? Thanks

 

[Brass Guy]

Several things come to mind.

• First, sorry to be the one to inform you that you do not have a battery pack with 85kWh of energy storage. 85 really was a misnomer from the start, but that's how Tesla badged it. IIRC, the 85 has 81kWh of storage, and about 77kWh of that is usable. (There is always a buffer at the bottom to prevent permanent damage that happens to Li- batteries when the voltage gets too low.)
• Due to inevitable degradation, you can't assume 100% is 265 miles or 77kWh usable. My 2013 S85 gets about 247 at 100% now. You'd have to do a 100% charge and note what the rated miles are when it finishes. (Always remember that >90% and <10% puts greater stress on the battery. Try to avoid leaving the SOC at these extremes for long periods.)
• Energy used for pre-heat, pre-cool, cabin overheat, computers, wi-fi receivers, and other energy use (aka vampire loss) is not factored into your Wh/m display. If you drove 154 miles but not in one stretch, every time you parked for a while some energy was used and not counted.
• There are a number of calculations that do not seem to sync up. I've often noticed that when I drive 5 miles, the Wh/m in the "since last charge" does not match Wh/m in the energy app "last 5 miles." Thus I conclude there is some fuzzy math going on anyway.
• The displayed rated range is often referred to as a guess-o-meter. There is apparently a very complicated algorithm the car uses to calculate it based on a number of undisclosed factors; likely including battery module voltages, change in voltage under various loads, overall pack temperature, energy used from or replenished to the pack, probably a bunch more. It is suspected that updates occasionally modify this algorithm.

For some people (me included) the math gets annoying, so learn to ignore it. Many drivers have stopped using rated range and changed their display to the "Energy" setting, displaying %SOC instead of distance. Others insist (I still doubt) that Tesla is "playing games" with the displayed range as you drive; if true you'll never figure out the math. The best you can do is to just drive and enjoy it. Do the math if you must, but don't let it bother you when it doesn't work out.

 

[AllElect2015]

That clears up a lot of things for me. Thanks for taking the time to write it all out. I suspected the radio and a/c power, heating, headlights, were not calculated in the number but now I know they are not. Love the ride and will just let the numbers be what they are. Thanks again for the info.

 

[Brass Guy]

Actually I think all power used is factored while you're driving, but not while the car is in "off" mode. For example, if you forget to pre-cool/pre-heat then crank it up and start driving right away, you'll have a much higher Wh/m for the trip; especially if it's a short trip. However if you leave "Keep climate on" for half a day, that energy won't be counted. Extensive use of pre-conditioning is how I keep my average down.

On that note, back on topic:
130,000 miles 290 Wh/m
Latest 6000 miles 272

 

[AllElect2015]

I assume you pre-condition due to colder weather/ hotter weather. As I live in San Diego (pretty temperate climate) and garage the vehicle would I still need to pre-condition? Thanks

 

[jerry33]

I assume you pre-condition due to colder weather/ hotter weather. As I live in San Diego (pretty temperate climate) and garage the vehicle would I still need to pre-condition? Thanks

Preconditioning is worthwhile anytime the temperature is colder than you are comfortable being in without a coat on. 10 C or colder is what I use, but mine is outside. It would need to be colder if it was garaged. Another criteria is any time it cold enough that you have reduced regen when starting to drive.

 

[huzz1970]

We have about 83000 miles on our 2014 S 85. We still trip charge above 250 miles (about right for 4.5 years of use). Usually, I charge to the break line between Daily and Trip. We have used average of 279 kWh/mi since delivery. We have gone on trips of 1000, 3000, 4000 and 6000 miles with only 1 use of non-superchargers (northern Minnesota) and one time when the police in Colorado Springs blocked off the parking lot where the Superchargers are located. We do not precondition- we live in AZ at 120F, and we have been at -5F in NM and CO in the winter. Only issue was we lost the original 12 volt after 18 months (about right for Arizona- we toss out 12V car batteries in about 2 years or less for the past 25 years.) The replacement 12V battery is still OK.
We have noticed that the main battery "as indicated" range does change from time to time, usually after software updates. I have not tracked this behavior carefully, so I cannot comment further. We use EV Trip Planner for trip planning, pretty accurate predictor, if most of the time on the conservative side of the estimates.

 

[jerry33]

 

[FlatSix911]

Jerry, go drive it like you stole it!

 

[jruiz510]

Any long term effects on the battery when driving at an lifetime average of 380 mi/wh? Given I only had my car for 1000 miles (brand new) and lost 5 miles of range on 90% charge. I've used the supercharger twice and the rest is the slow charging stations.

 

[jerry33]

Any long term effects on the battery when driving at an lifetime average of 380 mi/wh? Given I only had my car for 1000 miles (brand new) and lost 5 miles of range on 90% charge. I've used the supercharger twice and the rest is the slow charging stations.

Here's what I think we know:
1. Leaving the battery at very high (100% or close) or very low (under 20%) for extended periods is damaging.*
2. Small cycles are better than large cycles.*
3. High temperature is detrimental.*
4. For a given power output, the lower the SOC (state of charge), the more heat is generated. (e.g. hammering the throttle at 90% is less harmful than hammering it at 30%.)
5. For long term storage 50% is best.
6. Charging at over 1C creates more heat than slower charging. (I think SCs are close to 1C, I don't know if that's changed).
7. An occasional charge to 93% or higher will engage the battery balancing circuits. Sometimes an unbalanced battery pack can show lower capacity than it actually has. You don't need to do an extended drive or anything, just charge to 93% or higher and the software will take care of it.

Without knowing what the starting 100% was, what size battery you have, etc. It's not possible to be more specific. Teslas are often delivered with a reading over the rated maximum (e.g. an 85 should have a ideal range maximum of 300 miles but might show 305 or 309 or some such on delivery). This extra disappears in a few driving days and may be what you're experiencing.

* Items that have the most impact.

 

[mrjedistud]

Several things come to mind.

• First, sorry to be the one to inform you that you do not have a battery pack with 85kWh of energy storage. 85 really was a misnomer from the start, but that's how Tesla badged it. IIRC, the 85 has 81kWh of storage, and about 77kWh of that is usable. (There is always a buffer at the bottom to prevent permanent damage that happens to Li- batteries when the voltage gets too low.)
• Due to inevitable degradation, you can't assume 100% is 265 miles or 77kWh usable. My 2013 S85 gets about 247 at 100% now. You'd have to do a 100% charge and note what the rated miles are when it finishes. (Always remember that >90% and <10% puts greater stress on the battery. Try to avoid leaving the SOC at these extremes for long periods.)
• Energy used for pre-heat, pre-cool, cabin overheat, computers, wi-fi receivers, and other energy use (aka vampire loss) is not factored into your Wh/m display. If you drove 154 miles but not in one stretch, every time you parked for a while some energy was used and not counted.
• There are a number of calculations that do not seem to sync up. I've often noticed that when I drive 5 miles, the Wh/m in the "since last charge" does not match Wh/m in the energy app "last 5 miles." Thus I conclude there is some fuzzy math going on anyway.
• The displayed rated range is often referred to as a guess-o-meter. There is apparently a very complicated algorithm the car uses to calculate it based on a number of undisclosed factors; likely including battery module voltages, change in voltage under various loads, overall pack temperature, energy used from or replenished to the pack, probably a bunch more. It is suspected that updates occasionally modify this algorithm.

For some people (me included) the math gets annoying, so learn to ignore it. Many drivers have stopped using rated range and changed their display to the "Energy" setting, displaying %SOC instead of distance. Others insist (I still doubt) that Tesla is "playing games" with the displayed range as you drive; if true you'll never figure out the math. The best you can do is to just drive and enjoy it. Do the math if you must, but don't let it bother you when it doesn't work out.

Brass Guy, thanks for your info. I have a 2013 P85 and my 90% has been at 223 miles, or 247.7 extrapolated to 100%. It felt low since last summer I was at 227 at 90%, but looking at your data our cars seem to parallel each other fairly closely.

 

[jerry33]

 

[[email protected]]

I've enjoyed being able to keep an eye on my lifetime average energy use, as I haven't ever reset Trip B. After one month of ownership in California and around 1500 miles my average is 326Wh/mi. How are you faring?

I'd love to see a future firmware update that lets me use my trip meters for trips, but still provides access to my lifetime average. I'd also appreciate an automatic trip meter (one that resets when you exit the vehicle), and a per-driver meter.

After 5 years and 5 winters in Sweden, my lifetime average is 242 Wh/mile (151 Wh/km)
Robert von Bahr

 

[OilAndGas]

303Wh/mi, 2018 75D, ~1500 miles. Mostly highway but definitely gunned the throttle many of times. Almost always in autopilot, never in range mode.

 

[Snerruc]

275 wh per mi lifetime for2 years+. A dramatic change with a software update about 2 months ago dropped my usage over 10%. My current 100% is 238 miles, but I often drive 220-230 miles with 40 - 50 mi left. Usually that is at or slightly over the speed limit. Anyone else have this happen?

 

[jerry33]

275 wh per mi lifetime for2 years+. A dramatic change with a software update about 2 months ago dropped my usage over 10%. My current 100% is 238 miles, but I often drive 220-230 miles with 40 - 50 mi left. Usually that is at or slightly over the speed limit. Anyone else have this happen?

Mine has always been like that.

 

[pvazquez03]

After 5 years and 5 winters in Sweden, my lifetime average is 242 Wh/mile (151 Wh/km)
Robert von Bahr

Wow, that's amazing. I'm getting 320 Wh/m avg over 9,000 mile with lite winters (California)

 

[Darmie]

This looks ok, right?

 

[Brass Guy]

Wow, what have you been up to?