Lifetime Average Wh/mi

[Boatguy]

Those companies (and Tesla) start by using the energy at the point where it enters the EVSE (Tesla would start where the the energy enters the onboard charger), and don't consider vampire drain as part of the charging efficiency (strictly speaking that's a load, not charging). The folks who get lower numbers measure from the wall and include any load such as vampire drain and preconditioning. Neither is wrong, but they aren't measuring the same things.

I'm not sure about the message here, so let restate my belief.

When charging the battery, it doesn't matter what drained it, we need to restore it. Tesla doesn't explicitly tell us the remaining kWh, nor the usable capacity of the battery, so there are two approaches to determine how much must be restored. The first is to use the percentage of battery remaining and make an assumption about the denominator used to calculate the percentage. For example 20% remaining in a 90D with an assumed usable capacity of 85kWh means we need to restore 80% of 85kWh = 68kWh.

The second approach is to use the Trip page that shows consumption since last charge. But this is only consumption while driving. If there is no significant vampire use between charges (e.g., charge, drive, charge), then the Consumption page should be accurate. That was the case I used in my calculations above.

The utility company is measuring what goes through the meter. My Juicebox is measuring what goes through the EVSE, and they are in agreement. To my knowledge, Tesla does not report to us the amount of energy that goes into the HPWC. So in my case I inferred it by using the utility company number, less the Juicebox consumption.

Then the amount to be restored divided by the amount taken from the utility company equals the charge efficiency factor.

Does that sound right?

 

[jerry33]

Then the amount to be restored divided by the amount taken from the utility company equals the charge efficiency factor.

Does that sound right?

That sounds right, but that's the efficiency from the wall which includes every bit of electricity used while the car is plugged in (whether it's technically used in charging the battery or not), not the efficiency of the EVSE, onboard charger, or EVSE plus onboard charger plus battery. There are several points at which measurements can be taken, and not all of the utility energy is used to charge the battery.

 

[mark80908]

I typically charge to 60%, starting at around 5 am, in order to keep my average SOC as low as I'm comfortable with. I charge at 40A.

​

- Mike.[/QUOTE]

Here's a tip I haven't measured, but I believe. You'll probably get better efficiency at lower current. At 40A, my cable is slightly warm which is wasted energy. Electrical Engineers call this "I Squared R Loss". For example, drop from 40A to 20A, you're taking half as much power from the wall, half as much voltage is dropped in the wires, so the car receives more voltage at half the current, so it's getting more than half as much power as before. I usually set mine to 30A thinking there's probably some current used by the car's internal charger setting a limit on this benefit.

 

[Boatguy]

That sounds right, but that's the efficiency from the wall which includes every bit of electricity used while the car is plugged in (whether it's technically used in charging the battery or not), not the efficiency of the EVSE, onboard charger, or EVSE plus onboard charger plus battery. There are several points at which measurements can be taken, and not all of the utility energy is used to charge the battery.

The EVSE should not be a source of energy loss as it's just a glorified switch, there is no energy transformation.

The bulk of the energy loss is in the charger itself, the rectifiers converting AC to DC, which I assume are voltage multiplying rectifiers so there is no need for a transformer. There is probably some line loss, but it's negligible in this equation. And the cells don't absorb 100% of the power presented, some small percentage is lost, but from everything I've read it's very very low in lithium ion. The energy transformation from AC to DC is the big loss.

As you pointed out there is technically some vampire during the charging cycle, but again if it's 1kWh / day and it takes 3-4hrs to charge, the vampire is maybe 150Wh.

The big question is why does my CEF compute to 96% and Mikerad's to 75%?

 

[Sparrow]

 

[tinm]

Classic 2013 S85, 44900mi, 339Wh/mi
33% highway, the rest local stop&go, hills

 

[jerry33]

 

[Nevek]

Jerry, I still think you must only drive downhill!

 

[jerry33]

Jerry, I still think you must only drive downhill!

Sparrow beats me regularly.

 

[ZBB]

Today is the 3 year anniversary for my S60…

Lifetime stats:

• 51,510 miles driven since delivery (ODO is 51,528)
• 14,783.6 kWh used (per the car)
• 287.0 Wh/mi average

I keep a log on the car and summarize these stats each month. Highlights:

• My least efficient month was when I first had the car -- 311.6 Wh/mi. Combination of learning to drive the car, plus it was a really hot month (June in Phoenix -- temps were over 110 for most of the 2nd half of the month…)
• My most efficient month was Feb 2015 -- 264.7 Wh/mi. Weather was mild, and I replaced the first set of tires towards the end of the month -- I'm guessing the original tires were pretty worn, providing less grip and better efficiency...
• Being in AZ, spring and fall tend to be the most efficient, with a small dip in efficiency in Dec/Jan due to a little heating use (temps rarely go below freezing). Wh/mi really goes up once highs are regularly above 100F and the pack cooling kicks in. But that only really impacts range by a few miles, and only when first cooling the pack down after being parked during the heat of the day.
• I had the drive unit replaced in Feb 2014. The first drive unit averaged 297 Wh/mi over 12.6k miles (each month ranged from 290 to 312 Wh/Mi). The second drive unit has averaged 284 Wh/mi over 38.9k miles (range of 265-312). The only individual months that were similar to the first DU were when we did some road trips -- the max non-road trip month on the 2nd DU was 299 Wh/mi).

I also log my Supercharger visits:

• 66 total Supercharger visits between Feb 2014 and Mar 2016
• 35 unique Supercharger sites visited. 17 sites visited more than once, with the 2 closest SCs visited 5 times each.
• 7,228 Rated Miles added via Supercharging -- so ~14% of total miles on the car
• Average Supercharging session is 50 minutes -- I have a 60, so we charge slower and tend to need to charge to a higher % than the larger batteries.
• On average, we added 110RM each session -- Start from ~66 RM and charged to ~175
• Most Superchargers visited on 1 day: 6. We drove 730 miles from Cannon Beach, OR to Milpitas, CA -- so hit all the I-5 Superchargers from Woodburn, OR to Vacaville, CA (we skipped Fremont and hit Gilroy the next morning…)

This has been the best car I've ever had. Never put this many miles on a car so fast. I plan on keeping it until I get a Model 3 -- so I'm guessing another ~30k miles.

 

[Camera-Cruiser]

This has been the best car I've ever had. Never put this many miles on a car so fast. I plan on keeping it until I get a Model 3 -- so I'm guessing another ~30k miles.

Awesome write up!
Can yo describe your driving style? Is it barefoot, big toe, egg under fun pedal? Do you use hypermiling techniques?

Or, tell the truth, you have your wife push start at every intersection and most hills.

But seriously, how do you do it. I tried to be "good" for a day, and got to about 335 wh/mi, but then a good song came on, and it was all over. Seriously.

 

[ZBB]

Sure… Here are some thoughts on my driving style:

• I'm not a hypermiler, but I have always driven all my cars with efficiency in mind (even my previous Boxster…). For example, I tend to accelerate out of a stoplight faster than other cars, but without flooring it. I also use cruise control almost all the time (I resume previous speed somewhere around 30-35mph and let the car accelerate above then). I also will cancel cruise control at about the right distance to let regen slow me down to under 5 by the time I need to stop -- so limit braking (I used to do this in other cards also - but with engine braking and downshifting partly through the deceleration since most of my previous cars were manuals…). I do punch it occasionally on on ramps
• I historically drove 5-10 over the posted limit, but over the last 3 years, I've shifted to driving posted to 5-over. Probably more a factor of getting older vs driving the Tesla!
• My office moved just over 2 years ago -- the new one is about 5 miles closer to my house. The old commute was ~50/50 street vs freeway. The new commute is either all street or 65/35 street freeway -- which has limited my speeds and improved my efficiency a bit -- 45-50 vs 65-70 for a part of the commute makes a difference
• I did practice some hypermiling techniques for a couple weeks this past March -- we did a road trip during spring break that was off the Supercharger highway -- and one stretch from Monument Valley to the Gallup Supercharger was pretty close to the max range of my car (187 RM estimated at an EVTripPlanner speed factor of 0.9 vs 192 RM avail on a 100% charge). So I was practicing to see if I could improve even more -- basically, I tried accelerating without exceeding ~30kW, and never exceeded the limit for about 2 weeks before the trip. That dropped my Wh/mi by another 10 vs my regular commutes (~260ish vs ~270ish). The full month of March (including the road trip) was 274Wh/mi over 2200 miles, and we made that long leg with more than enough range remaining -- I beat the EVTripPlanner estimate by about 7 RM -- arrived with 13 RM remaining -- and temps at the beginning of the drive were in the upper 20s!)

 

[Camera-Cruiser]

I've stopped flooring it, mostly too. I think being in Southern California makes it a bit more challenging. The speed limit is an incredibly loose guideline here. +5mph will get you shot, +10 flipped off, +15 and you won't get invited to dinner again. Or, your going 3mph in bumper to bumper traffic and you can be doing either of the above in the same commute.

So that probably accounts for my high Wh/Mi figures and loosing more of my grey hair.

Thanks for your reply.

 

[ZBB]

AZ is similar -- and I'm often blown past when driving just 5 over… I decided I'll just stick to the right lane, not care, and listen to my podcasts...

 

[Camera-Cruiser]

AZ is similar -- and I'm often blown past when driving just 5 over… I decided I'll just stick to the right lane, not care, and listen to my podcasts...

That will work too!

 

[ArtInCT]

After 3 months of ownership here are my P90DL's numbers

Current Month
Distance = 1042.6 miles
Total energy kWh = 450.1
Avg energy / Mile in Wh/m = 321

Lifetime (3 Months)
Distance = 3118.5 miles
Total energy kWh = 1048.2
Avg energy / Mile in Wh/m = 329

In general I have been cutting back my charge threshold to now 70% (was at 80%~) as I just do not need the range as my daily use is under 35 miles per day usually.

Also, over the last month, have been charging once every 2 days but keeping the car connected to wall power.
I have seen no (0) range degredation and my 90% charge continues to show 242 Miles of range.

 

[JKW]

P85D - 13172 miles 4977 KWH - 310 WH/MI

 

[Tony8489]

First 2 months of ownership of S90D, 4/2-6/2, includes 3 trips Glendale-Mammoth, the last returning home via Yosemite:
781kWh home charged, usually to 70%
3533 rated miles supercharged x 90/290 = 1097kWh supercharged
4499 actual miles driven, that comes out to 431 Wh/mi

Car's trip mile readings today:
4654.3 miles driven
1655.5 kWh used
355 Wh/mi

So is 355/431= 82% the charging efficiency? Or is it 1655.5*4499/4654.3/(781+1097) = 85%

The 355 trip mile reading seems reasonable since most of the Mammoth trips are on cruise at 80-85mph. To me the point of having a car with this much performance and travel capability is to drive it as I would a comparable performing ICE car. We are delighted so far. I calculate the home charging at 7.0 cents/mile.

 

[jerry33]

 

[jstack6]

The best I can get is about 250 Wh/Mi. Average seems to be about 360. By the way 250 is about 4 miles per kWh that EVs are said to average. I'm a hyper miler and used to get 5-6 miles per kWh in a LEAF, FORD Focus EV and our KIA SOUL EV. It's very hard in our S 85 since it's bigger and heavy.
We have a model 3 on order and that should be much more efficient. We will see. Some friend have a Chevy SPARK EV and they are very efficient but only Tesla can go 250 miles plus on the Highway and has Super Charging.