Navigation algorithm wrong or based one what?

[dwbv]

2015 P85D

I've got a 140-mile trip to the nearest SC in a couple days and was playing with the navigation system. I set the destination for the SC and the system came back with 4% remaining starting with 87% (or 216 rated miles)... so is the navigation system telling me my efficiency is going to be that poor? If I do the math, the system is saying it will cost me 206 rated miles to travel 140 miles?

I plan to charge the car to 100% before I depart to make sure I make it without having to stop however now I'm curious why the system is wrong or why the system is right.

Do we know what the current navigation system bases this prediction on? Does it take into account my driving patterns or in this case, the previous owner's driving patterns since I've driven my car less than 30 miles since ownership. The dealership was also driving the car like it was stolen for the prior 20-something miles before me as well (So this is what 3rd-party dealers do to P-series Tesla vehicles; enjoy!).

I'm sure the trip screen will gradually change as I drive and get closer to the SC, hopefully change in the direction of more percentage upon arrival. I'm planning to go 65mph all the way there.

 

[Tam]

2015 P85D

I've got a 140-mile trip to the nearest SC in a couple days and was playing with the navigation system. I set the destination for the SC and the system came back with 4% remaining starting with 87% (or 216 rated miles)... so is the navigation system telling me my efficiency is going to be that poor? If I do the math, the system is saying it will cost me 206 rated miles to travel 140 miles?

I plan to charge the car to 100% before I depart to make sure I make it without having to stop however now I'm curious why the system is wrong or why the system is right.

Do we know what the current navigation system bases this prediction on? Does it take into account my driving patterns or in this case, the previous owner's driving patterns since I've driven my car less than 30 miles since ownership. The dealership was also driving the car like it was stolen for the prior 20-something miles before me as well (So this is what 3rd-party dealers do to P-series Tesla vehicles; enjoy!).

I'm sure the trip screen will gradually change as I drive and get closer to the SC, hopefully change in the direction of more percentage upon arrival. I'm planning to go 65mph all the way there.

I think it's a guidance just like the EPA ratings and not a guaranteed accuracy for your actual drive.

I've driven S, X, 3 since 2012 and my rule is to charge an extra 100 miles before I start my trip.

You said 140 miles then I won't leave until the battery gauge says 240 miles.

You said the computer says it's ok to leave with 206 miles but I would not.

 

[dwbv]

I think it's a guidance just like the EPA ratings and not a guaranteed accuracy for your actual drive.

I've driven S, X, 3 since 2012 and my rule is to charge an extra 100 miles before I start my trip.

You said 140 miles then I won't leave until the battery gauge says 240 miles.

You said the computer says it's ok to leave with 206 miles but I would not.

I kinda figured it was more of a ball-park estimate than actual since there's no way it can account for driving habits and pattern. I was able to test the charge up to 99% from prior and it was showing 248 rated miles so I won't be departing with less than 99% charge.

This will be my first long-distance trip with my new car so I'll record the trip progress and see how close or far off the navigation system is when I reach the SC.

 

[ucmndd]

I generally find the nav to be pretty damn accurate as far as range estimates go. Maybe slightly conservative but not a ton.

 

[PCMc]

In terms of what the navigation estimate includes is the following:
- the terrain of the road you are driving, so elevation changes are taken into account
- normal driving patterns for vehicle speed.
- estimated energy to warm the battery if you're starting from dead cold
- more recently it will try to estimate for wind based upon current weather conditions along the route.

Once you start driving it adjust it's prediction for estimate upon arrival. Overall for me it tends to be generally pretty good, but weather is the biggest factor it does not predict well. I find it tends to under predict impact of strong winds and cannot predict for conditions like rain or snow.

 

[dwbv]

In terms of what the navigation estimate includes is the following:
- the terrain of the road you are driving, so elevation changes are taken into account
- normal driving patterns for vehicle speed.
- estimated energy to warm the battery if you're starting from dead cold
- more recently it will try to estimate for wind based upon current weather conditions along the route.

Once you start driving it adjust it's prediction for estimate upon arrival. Overall for me it tends to be generally pretty good, but weather is the biggest factor it does not predict well. I find it tends to under predict impact of strong winds and cannot predict for conditions like rain or snow.

Thanks for the info. I am very curious and looking forward to my "real world" performance when I finally make it to the SC. This will literally be my first road trip in an EV and I'm planning to not stop at all. I should make the 140-mile trip easily with a 99% charge and I have no intention on bringing a lead foot. It will be a solid 65-70mph drive all the way while monitoring the trip prediction on the main screen.

 

[dwbv]

Well, I humbly admit that my faith in Tesla's trip computer has now been elevated. That damn thing sure knows what it's doing in calculating arrival percentage.

I started my 141-mile trip to the SC with 244 miles at 98% SoC in limp mode and a faulty battery heater.

The trip computer said I was gonna arrive with 17% (or 42 miles if you do the math).

Being this was my first road trip in an EV ever (plus limp mode and I wasn't planning to stop), I held my breath and got up to 70mph slowly and cruised to a pleasant surprise as the destination percentage began to rise to 24% (or 60 miles) by mile 97.

And finally got to the SC with 24%! Just like it predicted, wow, it was spot on! Amazing!

61 miles remaining. I made the 141-mile trip in limp mode. The car drove perfect all the way. If you add 61 + 141 = 202 miles meaning somehow I lost 42 miles along the way. Maybe it was to the HVAC set to 68F the entire trip? The 21" turbine wheels perhaps? No matter, range is relative at this point.

I am impressed to say the least. So far I've driven my car 312 miles total since ownership and 282 of those miles have been to the SC and back, lols!