Mysterious 5% range increase immediately after leaving Supercharger

[drewg123]

For the first time in over 2 years, I took a multi-state, multi-supercharger road trip in my 2017 MX 100D (~50K miles). This is the first time I've supercharged in ~2 years. And wow, there are a lot more superchargers now than there were 2-3 years ago! But I noticed something odd I'd like your opinions on..

I'm a "If you pull into the supercharger with more than 7% range, you're doing it wrong" kind of guy. In previous road trips during the pandemic, I noticed that the range estimates provided were typically very conservative. Eg, if I left a supercharger when it was estimating a 5% charge at the next arrival, I'd often get there with 8-10% or more (or less, if the weather was bad). As I was driving, I'd notice the percentage at my destination gradually climbing, so I'd often skip the suggested supercharger and continue to the next one.

This trip, on more than one occasion, I noticed that the range jumped by 5% almost immediately after unplugging from the supercharger. On my last stop on the way home, it wanted me to charge 10 more minutes, and I unhooked at 5%. As soon as I pulled out, before I even got onto the interstate, the range jumped to 10% (and it was accurate, as that was my SOC upon arrival at home).

Did something change about Tesla's range algorithms? Do they use a different algorithm when charging and when driving? Or is there some weird issue with my car? I was getting close to my lifetime average of ~340Wh/mi, so nothing should have surprised the algorithms.

 

[The Lorax]

I've had similar experiences starting sometime last year. I drive a 2016 MS and now find that when I leave the SC it will often improve my estimated range by up to 8-10%....but then sometime later in the trip, it will drop quicker than it should and use up some or all of that 'extra' range. I suspect that it's the temperature of the battery leaving the SC that is driving this but I don't know why Tesla hasn't found a way to account for it.

 

[drewg123]

I've had similar experiences starting sometime last year. I drive a 2016 MS and now find that when I leave the SC it will often improve my estimated range by up to 8-10%....but then sometime later in the trip, it will drop quicker than it should and use up some or all of that 'extra' range. I suspect that it's the temperature of the battery leaving the SC that is driving this but I don't know why Tesla hasn't found a way to account for it.

That makes sense. It was a very hot day, and the charger was in direct sunlight. Thinking about it, most of my longer road trips have been in cooler conditions. The taper was worse than I recall, and I've been assuming that was because it was warmer.

 

[Zuikkis]

Just did a 3700km road trip on a 2016 MX. I noticed the same thing, pretty much always when leaving the SC.

I think I figured it out. It uses your actual consumption data when entering SC, to calculate how long you need to charge. Then when you leave, it recalculates the route but this time it uses the "typical" consumption data so the result usually is different. Sometimes it even rerouted to a different SC at this point, thinking you could skip the next charger.

However after driving for a while it notices that your consumption is higher than typical and everything reverts back to the original plan.

I don't know if this is a bug or is it intentional? It's showing you what you could reach if driving more economically.

 

[Big Earl]

This isn't really a range increase, so to speak; more of a recalculation of the route plan's energy consumption estimates. Why this happens, I don't know, but it isn't unique to your car.