I don't think you understand. That's the difference between reported consumption and actual consumption. It is not about higher than usual consumption. I could be driving on flat tires, for all it matters.
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I don't think you understand. That's the difference between reported consumption and actual consumption. It is not about higher than usual consumption. I could be driving on flat tires, for all it matters.
In the summer yes. (That one time) when reported consumption was under 310 Wh/mi, the discrepancy was "only" ~3.5%. Of course, in favor of the car reporting better numbers than it was achieving.
Is there any number on or about this car that actually tells you the right amount?
I think rated miles used is the best thing to go on, because it's based on battery capacity, which includes all power usage, vampire or driving. Can you tell me how you calculated the 3.5% discrepancy when you were at 310 Wh/mi? I would think with your car, something close to 300 Wh/mi should give you close to rated miles performance, and it seems like in your example you were close to that.In the summer yes. (That one time) when reported consumption was under 310 Wh/mi, the discrepancy was "only" ~3.5%. Of course, in favor of the car reporting better numbers than it was achieving.
Is there any number on or about this car that actually tells you the right amount?
312Wh/mi is rated for my car. The discrepancy is between the Wh/mi reported by the trip meter, and computed one from rated miles used:
(RMs - RMe)*RMc/M
Where:
RMs = Rated miles stating
RMe = Rated miles ending
RMc = Rated consumption Wh/mi
M = actual miles
For a long time I was satisfied with what the trip meter was reporting, but I was not checking rated miles. I got this idea from teslafi.com, which will do this calculation for you.
The rated miles is difficult to game because of simple mathematics. They could be fudging the rated consumption internally (and there is evidence that they do over time), but rated miles comes out and goes back into a fixed pool, if it just "lost" miles over time you'd end up with negative rated miles or really high rated miles, so you can't have any gaming that results in loss over time.
I think the problem then is the distance. 16 miles isn't really enough to give a reasonable measure of consumption because the start up usage is going to be a high percentage of the power used. Even though you've warmed it up by preheating and ending the charge just before you started to drive, there is still more power used in the first couple of minutes.
FWIW, my opinion is that Ideal miles is better for this kind of thing than Rated miles because they seem to mess with the algorithm less in Ideal miles.
For WHAT?
edit - Not to mention my main complaint above was how it was not reported by the trip meter, and secondarily the ridiculous consumption.
Do you have any data to show diverging of the apparent fixed ratio between ideal and rated miles? None of the loggers I have log ideal miles, so that will have to be fixed. I haven't spotted it by eye.
I haven't logged any data. I check both somewhat regularly and they are different. The Ideal miles is supposed to be based on a steady speed of 55 mph with no other factors added.
What I "think" happens when you start is that it runs a check on all of the systems. Just doing the driveway shuffle can easily get over 1000 Wh/mi. It goes down the longer you drive it.
Missile Toad
MSLR Wht/Blk/19 | OD 6/10/21 | RN11512
So, based on a few months of watching my car's behavior, I've reached this conclusion:
|»»»»»»»»»»»»|- - - |»»»»»»|
.kWhr kWhr Kwh- - - kWhr kWh
RM RM RM RM RM rm rm RM RM R
.............vampire
»- - - - time - - - ->
So, in above chart, '»' signals movement/driving, and '-' is parked, e.g., overnight.
kWhr in trip odometer = all current used in a trip
RM changes in IC = all current in trips AND while parked during the measurement interval
RM changes in IC = all current in trips AND while parked during the measurement interval
|»»»»»»»»»»»»|- - - |»»»»»»|
.kWhr kWhr Kwh- - - kWhr kWh
RM RM RM RM RM rm rm RM RM R
.............vampire
»- - - - time - - - ->
So, in above chart, '»' signals movement/driving, and '-' is parked, e.g., overnight.
This is true. However, I'm excluding vampire RM loss in my analysis above. It is strictly RM at start versus end of drive, no waiting. This is actually optimistic for Tesla, since a bunch of the vampire loss is just charging the 12V system, which depending on loads was probably draining during your trip. So you have delayed consumption from your last drive that shows up as "vampire" loss.
*IF* the trip meter was accurate, then the vampire loss would show up there, among other things.
Missile Toad
MSLR Wht/Blk/19 | OD 6/10/21 | RN11512
@AWDtsla I'm understanding. The 12V system is a little like a laptop that is plugged into the USB/auxiliary port in a regular car. Except in a regular ICE, that current has to be generated off the alternator, and the fuel, through combustion, runs that alternator. From that point of view, any losses in the 12V have to be attributed to the trip... even if the 12V 'fasts' during the trip by not recharging from the main battery (60+ kWhr). I don't know that much about the architecture and/or interdependencies, so I'm taking what you say (and I have read from others) as accurate, that the 12V system draws some small, but measurable extra current to sustain some of the 'overhead' functions (I'm supposing, it handles instrument cluster, center console display, CPU, and all other 'thinking' apparatus other than the A/C, speakers and lighting).
So if my understanding is correct, the trip meter is concealing some of the true energy used to make the trip from A to B happen. Having said that, I'm thinking that none of this will hurt your chances of reaching the full RM of the main battery on your A to B trip, and that the only impacts, is that post-trip, you get to charge your battery, possibly, beyond the factory specified top-limit on the battery -- only because, as you charge the big 60+ kWhr, that 60+ kWhr is dumping some charge onto the 12V system.
Updating the heavier 'vAMPire', where uppercase signifies deferred charging from the trip:
|»»»»»»»»»»»»|- - - |»»»»»»|
.kWhr kWhr Kwh- - - kWhr kWh
RM RM RM RM RM rm rm RM RM R
.............vAMPire . from 12V
»- - - - time - - - ->
So if my understanding is correct, the trip meter is concealing some of the true energy used to make the trip from A to B happen. Having said that, I'm thinking that none of this will hurt your chances of reaching the full RM of the main battery on your A to B trip, and that the only impacts, is that post-trip, you get to charge your battery, possibly, beyond the factory specified top-limit on the battery -- only because, as you charge the big 60+ kWhr, that 60+ kWhr is dumping some charge onto the 12V system.
Updating the heavier 'vAMPire', where uppercase signifies deferred charging from the trip:
|»»»»»»»»»»»»|- - - |»»»»»»|
.kWhr kWhr Kwh- - - kWhr kWh
RM RM RM RM RM rm rm RM RM R
.............vAMPire . from 12V
»- - - - time - - - ->
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ArtInCT
Always Learning
After 10 months of ownership here are my P90DL's numbers
Current Month
Distance = 867 miles
Total energy kWh = 319
Avg energy / Mile in Wh/m = 369
Avg Temp 36.8F
Lifetime (10 Months)
Distance = 12,365 miles
Total energy kWh = 3971
Avg energy / Mile in Wh/m = 321
Wh/m really went up this month, probably due to the cold weather and my typical short drives.
Range Mode off all month until the last two weeks.
Range Mode on really does help to reduce Wh/m but pack stays colder longer.
Current Month
Distance = 867 miles
Total energy kWh = 319
Avg energy / Mile in Wh/m = 369
Avg Temp 36.8F
Lifetime (10 Months)
Distance = 12,365 miles
Total energy kWh = 3971
Avg energy / Mile in Wh/m = 321
Wh/m really went up this month, probably due to the cold weather and my typical short drives.
Range Mode off all month until the last two weeks.
Range Mode on really does help to reduce Wh/m but pack stays colder longer.
My head was spinning trying to analyze this. From your first example of 30 rated miles used and 421 Wh/mi reported efficiency, I would agree that your car is under reporting actual usage. I say that because if you take 6.82 kWh (which I get from multiplying 16.2 x 421 from your first example) divided by 30 rated miles, that gives a reported rated efficiency of 227 Wh/mi, which is way too low. That means it is under reporting actual usage. At least in theory, while you are driving, all usage should be reported and computed into the driving efficiency. So somehow, your car (at least in that one case) was using extra energy that it wasn't accounting for. If included, this missing energy gave you a pretty ridiculous Wh/mi value (in the 500 range), although only reporting 421 Wh/mi, which is still pretty high.
Your second example from the summer when you achieved 310 Wh/mi, seemed fairly normal.
BTW, where did you get the value of 312 Wh/mi as rated value for your car? Is your car rated at 270 miles?
For my car, I think my odometer Wh/mi is pretty accurate, but my actual miles are usually between 80 to 100 % of rated miles. I also monitor usage from my wall meter, so I have an additional data point to compare to.
FlatSix911
Porsche 918 Hybrid
Oh, I don't think it's "my car" at all. It's just that most people trust the trip meter.
That's not ridiculous yet. It's ridiculous when it goes over 1000 Wh/mi when it gets really cold out.
Was not normal. Was driving with cruise control with no slowdowns for like 50mi at 70ish, slightly downhill, 50F, no HVAC. There's no correlation to actual Wh/mi that I've found. Just did a couple drives this afternoon. Drive at 399 off by 8%, drive at 439 off 12%, drive at 488 off by 12%.
Energy analyzer rated line, confirmed like 5 independent ways. They said my car should be 270 when I bought it. Never saw above 268, even with double digit miles on the ODO.
Try using teslafi.com. I think people will discover how much BS the trip meter is.
Actually, the trip meter is working pretty well for me. I record my car's usage data at the end of each day. This graph is about 1 years worth of data. I plotted it against the teslafi formula using my rated value of 262 Wh/mi and you can see most of the results fall within the 5% line. The ones that fall below that are when my car reports unusually low rated mile consumption (Wh/rated mile consumed), which isn't often. I also plotted my wall usage which shows my actual energy usage including the charging efficiency.
Most of time I achieve between 80% to 90% of rated miles, with mostly stop and go local driving. The longer trips on freeways is where I get the 100% rated miles performance.
I'm not sure what information teslafi.com provides that you can't get from your car. Maybe I will look into it.
edit: The legend should say Wh/mi, not kWh..
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Don't know where you got this 262 number, but it seems wrong. Last time I checked 75D was 290. I don't see how this adds up with you achieving 80-90% of rated miles, yet having a consumption number that's even lower than rated? Also, you're showing that the from the wall usage is 25% higher? Gen2 charger efficiency is 91-93%. There's a huge amount of missing energy there, depending on your ratio of actual miles of vampire drain.
The 262 number comes from my data from the car. I achieve rated miles when I drive at 262 Wh/mi, which is usually only on the freeway. The value of 290 is the line on the energy graph, but it is incorrect. I don't achieve close to rated miles at that rate. That number would only make sense if I was able to use the full 70 kWh of my battery, but usable is less than that. I figure my usable, based on my numbers is around 60 to 62 kWh, and that is consistent with my 262 number (262x240 rated miles) = 60 kWh.
The chart shows that I usually achieve 80 -90 % of rated miles. Those are my actual numbers. Many others have reported wall efficiencies close to mine. Although vampire loss is a factor in the efficiency, it doesn't change the numbers that much.
The EPA rating for my car is 33 kWh/100 miles. From my chart I am using about 32 kWh/100 miles when I my driving matches rated miles, so that is a pretty good check on my numbers also.
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glhs272
Unnamed plug faced villian
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