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Difference in wh per km
- Thread starter Chetanh
- Start date
No, it's not a rounding error.
They are measuring different periods of use. Notice how the one on the left is "Since 03:53PM", and the one in the energy graph on the right is showing the average during the past 50 km of distance? Those are not the same time periods.
Manitoba Keith
Member
I started driving at 3:53 and covered 50kms of my 75km commute.during that time so both are measuring the same distance and time.
Usually i am at 130wh/km. There was a bit of traffic on the highway so the car was doing between 80 and 100kmph. Usually i do autopilot at 110 and get 130wh/km
AlanSubie4Life
Efficiency Obsessed Member
Not a rounding error, but the trip meter sometimes has some delay on its updating (might update every 0.1mi). You picked a time when you happened to be substantially below the long term average in terms of instantaneous consumption.
I'd suggest driving at a speed which is giving you something close to the average consumption (so something like 100Wh/km rather than 50Wh/km), at a steady rate, for a minute or two, and then take another picture where the short term average is the same as the long term average. It may align better.
I have seen people post that these things align, and I've checked myself exactly once. In general it did align but it may not align perfectly at all instants in time (though I haven't seen something like this).
That being said, this actually seems like kind of a large error - it's about 250Wh over the 50km interval. I can't really see the updating lag cause quite that much of an error for that longer interval.
If you can reproduce this consistently and it never aligns, let us know.
As I originally stated, I've tested it several times, the two figures will be close enough to be a rounding error, whatever you want to call it, it's within the margin of error, due to the rounded increments of measure, time or distance. Why do people like to make simple things hard? There's no practical difference between 98 and 103Wh/km
darth_vad3r
Well-Known Sith
How slow are you going to get 100 Wh/km??
103 Wh/km x 50 km = 5.15 kWh
98 Wh/km x 50 km = 4.90 kWh
The difference is 250 Wh, which is like a few km of downhill regen or a few seconds of heavy acceleration.
When I happen to notice near a rollover of my trip to the chart, it is usually below or above by a tad before, then it goes through and crosses over. So for a moment they are the same or cross paths.
Oh, and the trip meter ticks up when the underlying number rounds up to 50.0, so you’re actual distance at that point is 49.95 km. Who knows how the “last 50” is updated and if it’s 100% up to date every second or not.
darth_vad3r
Well-Known Sith
SR+?
I’m similar with ~130-140 Wh/km with AP set at 110-115 km/h.
I have some hills though. I guess bad traffic is good for something, eh? [obligatory “eh” required by international Gen-eh-va convention when conversing with fellow Canadians]
Interesting. I've checked mine several times on road trips and mine are usually pretty far apart. ~10% difference is not uncommon for me.
Yes SR+
Drive today to work was similar. A consistent difference of 250WH over 50 kms.
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darth_vad3r
Well-Known Sith
Hmmm.
Next, check at 10.0, 25.0, and 50.0 on the same trip with no stops and see if there is a pattern.
I don't believe this is accurate...Are you suggesting that my trip meter is going to say I have traveled 0.1 miles after only 0.05 miles?
darth_vad3r
Well-Known Sith
Yes. Try it. Drive 0.1 miles one way, then turn around and go back til you get to 0.2 miles.
0.1 = 0.05, 0.2 = 0.15, ... subject to delays in updating if any.
Everything on the display is rounded. Underlying the trip meter, the odometer is actually ticking off in meters. You can see the odo reading in miles in the API has something crazy like 6 decimal places
darth_vad3r
Well-Known Sith
Which one is “the consumption meter”, the chart? This is possible. It could be continually updating 50km using 1km averages and not be matching with the trip meter’s “50.0km” until an entire 1km bucket has filled up.
darth_vad3r
Well-Known Sith
Yes. Try it. Drive 0.1 miles one way, then turn around and go back til you get to 0.2 miles.
0.1 = 0.05, 0.2 = 0.15, ... subject to delays in updating if any.
Everything on the display is rounded. Underlying the trip meter, the odometer is actually ticking off in meters. You can see the odo reading in miles in the API has something crazy like 6 decimal places
Thought of another easy test. Drive til you see the trip meter get to 0.1 miles and stop. Switch to km.
Does it say 0.1 km or 0.2 km?
0.1 miles is 0.16 km (0.2).
0.05 miles is 0.08 km (0.1).
Yes. Try it. Drive 0.1 miles one way, then turn around and go back til you get to 0.2 miles.
0.1 = 0.05, 0.2 = 0.15, ... subject to delays in updating if any.
Everything on the display is rounded. Underlying the trip meter, the odometer is actually ticking off in meters. You can see the odo reading in miles in the API has something crazy like 6 decimal places
Yeah, miles are not rounded at the tenths. I measured .1 miles on google earth, my display didn't go to .1 until it actually went .1 miles.
Now whether km is rounded I haven't tested, but miles is not.
And the display updates every .1 of whatever unit for the trip counters, doesn't matter the time.
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