This same phenomenon of the car underestimating charge to destination and rerouting effected me a few weeks ago. I was on a day trip to the county which represented about 150 miles round trip. No problem I thought, just take the precaution of charging to 100% and it should be no sweat. Well, at the destination we ran into the mother of all traffic jams around a Renaissance festival. Literally 90 minutes crawling the last 9 miles. The good news is that an electric car consumes very little juice when stopped in traffic like this while all the ICE machines around me burn the last of the planet's fossil fuel. I didn't fret the range; I knew I had plenty. And then it was even worse on the way back! Now I was doing some calculations in my head. Once I got under way I engaged the nav to get a home ETA. Well it refused to go straight home but rather insisted on sending me to a Supercharger that was considerably out of my way. My head said that I should have 50 miles at least when I got home. The problem (from the Nav's perspective) was that I was just sitting in traffic getting awful efficiency readings like over 1,000 Wh/mi. It was based on that efficiency that it was projecting range before recharge. After I convinced myself what was going on with the nav routing I just turned it off and proceeded straight home. To test the theory, after 25 miles of highway driving I asked Niki to nav me home and sure enough it had a reasonable recent efficiency value to go on and projected that I should arrive home at 22% SOC. And indeed that's what it was when I drove in the driveway.So picked the 101. Here are a few items from the last few hours:
1 - There are instances where the Tesla navigation will tell that you have charged enough to get to your destination or the next charger (with a 10% buffer). Sadly, I had two instances where after a few miles of driving, it changed its mind and asked me to turn around, saying I would need to charge another 5 minutes before leaving the same charger I just left.
The first time was after leaving Gilroy on the 101 going south. I fought the nav for a bit, and after restarting the trip, it offered to divert to Monterey/Seaside on the way. I did so.
Just before I got to Seaside Tesla (yay, lounge snacks!) I called the Mothership. Tech support told me that engineering was aware of the issue. The current quick fix is to shut off nav for a few miles, and try again.
Upon leaving Seaside, it complained similarly. By the time I left, I actually was looking at a 20% buffer at my next charge stop. I gave it a few miles, tried the nav again as suggested, and it sorted itself out.
Next charge was giving me a 31% buffer, and this time nav was happy. Maybe anything at or below 20% (yellow) is a trigger.
2- I assumed I would have plenty of time while charging to pick a route, upload pics, document, post here, tweet, text my wife and walk around. False! Am scarfing a meal down, as my car, as usual, will be ready before I am.
