Nav system energy display glitch: possible cause

[dgpcolorado]

I think I saw at least one other report of this: I was on a trip and the energy display to my destination would refresh briefly to a 10% higher number for a few seconds before going back to the previous pessimistic projection. I may have figured out what was going on, at least in my case. The details:

I was making a trip from my home in the mountains to the Blanding UT Supercharger Station (camping trip in Natural Bridges National Monument). With a 90% charge, the energy projection had a surprisingly low 6% projection for my battery at the destination. By contrast, EV Trip Planner said I can make it easily, especially in the downhill direction. So I set off, figuring I could drive slowly if necessary, and after ten or fifteen miles I saw the destination energy projection cycle briefly from 6% to 16% then back to 6%. It did this several times at random intervals. Had me puzzled. Then I noticed that "Tessie" the nav system had me making a turn at a highway junction when I always go straight. Sure enough, when I passed that junction Tessie recalculated my route and my energy projection fixed on 16% remaining; I eventually got into Blanding with 14%, driving the speed limit on cruise the whole way except for some really fun twisties (I always zoom through those).

So, for reasons I don't understand, Tessie routed me over the mountains on a twenty (!) mile longer route, with thousands of feet of elevation gain, as opposed to the much lower, easier, shorter route around the mountains. I didn't notice because no local would even consider the route Tessie chose, it is absurd to go that way (and, unlike Google maps, there doesn't seem to be any way to change the route on the Tesla nav system).

Not too surprisingly, the same thing happened on the way home from Blanding: Tessie chose the twenty mile longer route over the mountains and it wasn't until I got to my turn to the correct route that the energy plot showed an additional 10% battery at my destination. Going the usual way around the mountains I started with 94% in Blanding and arrived at home with 14% (next time I will just charge to 90% in similar mild weather conditions).

So, if others see the energy plot cycling between projections, perhaps Tessie is measuring alternate routes. I've never seen this happen on ordinary freeway road trips but mountains with varying route choices seem to cause issues. Thats fine for me on my home ground but it could be a problem for tourists driving the mountains. It would be crazy to go over the mountains rather than around them unless mountain sightseeing was the goal of the trip. But how would visitors know that unless they had preplanned their routes?

Anyway, I throw this out there as a possible reason for energy plot glitches. FWIW.

 

[ibdb]

I don't monitor the trip planner often, even on long drives, but I did happen to monitor it on a drive North on I-5 from Portland headed towards Seattle recently. I also saw some sporadic 10% changes in estimated energy remaining. I'm not sure exactly what alternate route it could have been considering, as there really wasn't much to choose from in the area I was traveling. That it was also exactly 10% that things were changing also makes me think that it was less about alternate routes and more likely to be something else. I don't remember when it was that it stopped with the 10% variance, though.

I do have a much longer, multiple supercharger stop, trip planned soon that will have me keeping more of an eye on the trip planner, so I'll have to see if I notice any patterns during that drive.

I can say that I still can't tell why the nav chooses the routes it chooses quite often. I'll regularly be given a longer, slower route as the initial route and, even if I take a shorter, faster route that I know to be clear, find the nav continuing to try to get me back to the original route. It happens whether I have the traffic aware function selected or not, as I'd originally thought that was a likely cause. It wouldn't surprise me if the strange routing calculations play into differences in the trip planner, but a consistent 10% variance makes me think it's something more.