-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Can Never Match Trip Planner Prediction
- Thread starter mknox
- Start date
-
- Tags
- Driving Dynamics Model S
Might be worth posting some recent SpC data here so we can really figure out what's the cause of your decreasing range. I remember with my original pack there was a noticeable "knee" in the taper curve that worsened over time. Folks speculated that the increased resistance due to degradation meant that the cells were not able to tolerate the faster charging speeds.
Cyclone
Cyclonic Member ((.oO))
Not that I have any such problem, but my engineering side would love to see this data. How do we collect this?
On a recent multi-leg trip to Seattle, I noticed that, although I could always beat the trip planner overall - it always seemed to underestimate the initial power requirements. It would predict something like 15% left, and it would drop down to 8% within the first few miles, then slowly climb back up as the miles increased.
One guess I had was that it simply assumed you were travelling at the speed limit when you started, and then got fooled by the fact that you actually had to start out, get onto the freeway and speed up. So it saw much higher consumption than calculated in the first couple of miles, which screwed up the prediction initially
One guess I had was that it simply assumed you were travelling at the speed limit when you started, and then got fooled by the fact that you actually had to start out, get onto the freeway and speed up. So it saw much higher consumption than calculated in the first couple of miles, which screwed up the prediction initially
cpa
Active Member
MK, your data does seem quite odd. I generally do better than the trip projection estimate when I utilize it. The journey from my home to the Manteca Supercharger is flat with speeds around 70. I always leave home with about a 60% charge and the trip estimator says I will arrive with 12%. I drive around 68-72 and always reach Manteca with about 15-16% using 270 wh/mile.
Perhaps a longer journey might shed better light on your situation? Good luck and let us know!
Perhaps a longer journey might shed better light on your situation? Good luck and let us know!
Oh just the regular taper curve that you get by reading the API values or manually plotting % and charger power should do. I noticed that there was a widening gap between my curves that corresponded to battery age and mileage.
bollar
Disgruntled Member
I'm with you mknox. I have never gotten the green bar above the grey bar with normal driving -- and the miss has been by as much as 2000 basis points (if Trip Planner says I will arrive with 20%, I arrive at 0%. My hunch is that the speed TP uses in its estimates are lower than the current speed limits. If I go the speed limit (75 around here), the miss is huge, but if I go 65, it appears to be what it takes to get actual energy to equal forecast.
This happened on every leg of this week's drive on Route 66. The most striking example was the long drive from Tucumcari to Shamrock -- 204 miles. TP said I could leave Tucumcari with 80-some-odd percent battery. Instead, I charged to 99% and arrived at Shamrock with 1%, never exceeding the speed limit, and actually driving 10 below the speed limit for the last 20 miles to make sure I made it. We had a slight quartering tail wind and about 600 pounds of passengers and cargo.
This happened on every leg of this week's drive on Route 66. The most striking example was the long drive from Tucumcari to Shamrock -- 204 miles. TP said I could leave Tucumcari with 80-some-odd percent battery. Instead, I charged to 99% and arrived at Shamrock with 1%, never exceeding the speed limit, and actually driving 10 below the speed limit for the last 20 miles to make sure I made it. We had a slight quartering tail wind and about 600 pounds of passengers and cargo.
CHG-ON
Still in love after all these miles
Agreed. I have found that it takes something like 15 min or miles to settle in and give an accurate estimate. It predicts optimistically right after charging. I learned my lesson to charge more when I almost got screwed using the initial estimate after leaving a supercharger. I always give a 25% buffer due to having a "+", with staggered tires, thus more rolling resistance, and a bit of a lead foot.
SeminoleFSU
Voluntaryist
In my example above, Off... but it was one of those "perfect" days so I wasn't even using the a/c. Just outside air through the vents with windows and pano roof closed.
I rarely Supercharge. Maybe once every 3 or 4 months on average. I have taken a couple of road trips to Chicago (last one in June) and there are only two within driving distance of my house so unless I'm in the area, they don't see much action from me.
I did another experiment yesterday: My commute is about 40 miles each way, and I always do better on the way home than on the way to work. So on the way home I tried real hard to see what would happen, figuring that trip would be my best bet to meet or beat the prediction line. About 30 of those miles are freeway. As soon as I got on the highway, I found a transport truck doing about 10 MPH below the speed limit (20 MPH below the actual flow of traffic) and nestled in behind for those roughly 30 miles. The rest of the way I drove like an old man, driving like I had an egg between my foot and the accelerator pedal. Another ideal weather day, so winds, HVAC use etc. were not a (negative) factor.
At home, my Average Energy for the trip was 246 Wh/mi (pretty good). The graph showed me very close to the prediction line, in fact above for a bit and below for a bit. But I arrived home exactly at the predicted SOC.
I'm not sure if this is a "success" because I had to hyper-mile like a fool on a route I know to be one of my most energy efficient just to match the prediction.
