1. I had a test PiP the other day. At -4°C outside, cabin temperature set to LO, LED headlights on, 76m altitude difference, I’ve made 12km on EV. I believe EV range is nearly linearly proportional to the outside temperature, given no other variables change (same car, same route, traffic conditions, red lights, load weight etc.). 2. You have statistically too little attempts on too narrow temperature range, to estimate the type of EV Range vs. Temperature relation reliably. I hardly believe the triple polynomial is the real relation as most physical processes are described with linear, squared, logarithmic or exponential relations. The only two of the high-school physics formulas I remember to be of the third order polynomial kind are volume vs. radius and force of gravity vs. distance (inverse). You were perhaps to eager to make the best fit and forgot the fact you actually started fitting to the measurement error along the way. My PiP is scheduled for April 2014. In my climate the outside temperatures range from -10°C to +35°C. I might contribute with the data I measure.
I wonder if you even bothered to read my first post to the end...let me help you: "Is the relation linear on a wider range of temps? I don't know, probably not, however, for the range recorded - a linear regression fits well with 0.38 slope (0.98 correlation)". This thread is not a thesis for a PhD degree! I simply try to share my experiences with other PC chatters to the benefit of all. Hope you will do the same once you have enough experience with the car. Speaking of too little attempts on too narrow temp range, I can see you jumping to conclusion based on one test drive. Your test drive is really meaningless not even being a round trip!
if you follow giora's line down and to the left, it looks like -4c corresponds to 12km? that's terrible! are you sure the battery was fully charged?
Good stuff! I've been getting about 12-12.5 miles of range on some very hilly and cold commutes the last week or so. Can't wait until the temps go up!
Giora sorry, I didn't want to step on anybody's toes. Just perhaps too strong choice of words, trying to tell you to drop the idea of triple order polynomial and pergaps get some more measurement in more extreme temperatures. Although it wasn't obvious, I do appretiate your work. I believe it took you a year or more, to collect the data on the full range of temperatures in your climate. Bisco, the battery was actually full. But cold. Anyway, I am pleased to see this was the worst case scenario and I can expect only better.
62 deg F today. Did my 9.9 miles morning trip. Display said 3.5 miles remaining. It is raining and I drove slower. Max speed I reached was probably 55 mph. I climbed the bridge at 45 mph requiring half HSI EV power bar. On a rush day, I would climb at 55 mph with HSI bar at 80% power.
Forget it - no biggy Temperatures lower than 6-7 C are very rare in my area, and I will probably use cabin heat (as an order from partner), so yes, it is very unlikely that I will add low temps data points. All my recorded trips are with 1-2 occupants. My curve fittings to my results were only to have another tool, example - linear regression with 0.14 slope indicates to me about 1.4 miles drop (or gain) per 10 deg F. I do realize my results were not achieved in a lab and cannot be reproduced, also - similar conditions are only similar (traffic, wind etc.) another difficulty is temp which is not always constant along the trip. On the other hand, I took several times this trip with another route (shorter by about 300 m but more traffic lights) and got almost same results for a given temp. I hope you will enjoy your new PIP as I and others here enjoy - it is an amazing machine. I have added some more trips to the charts, now 28 altogether. I have also improved the appearance for better readability. The middle line is a linear regression of the data points. The two other lines show what can be called "bend of high probability": for every temperature it shows what most probably will be my actual EV range. Happy new year everybody!
Seems to be going wet and cooler this week but doubt if it will drop less than 7-8 C minimum at nights.
12 degrees out...and out of range (but I had a warm engine). So I pulled out the old pulse and glide tricks and did 78 mpg over about 7 miles. (virtually no elevation change)
2.7 miles to coffee all EV -15 below no ICE. Heated garage 45 degrees. Will see what happens after coffee.