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On today's TMC Podcast, we ask the question "What is the Tesla Cybercab?". Join us on YouTube live at 1PM and participate in the chat.
Wind speed is important...
I too have found the trip planner to be accurate - except when there are en-route winds. I realise there are many complications, but as a pilot I am wondering if the en-route forecast could be included in the energy requirement calculations. An average 40kph headwind will make a huge difference to energy consumption (it works out as the square of the vehicle speed - if you add 40 to say 120kph this is a significant increase) - I routinely check the wind forecast before trusting the trip planner!
Apologies for the metric units but I live in one of those modern 'international' countries! (Australia)
I too have found the trip planner to be accurate - except when there are en-route winds. I realise there are many complications, but as a pilot I am wondering if the en-route forecast could be included in the energy requirement calculations. An average 40kph headwind will make a huge difference to energy consumption (it works out as the square of the vehicle speed - if you add 40 to say 120kph this is a significant increase) - I routinely check the wind forecast before trusting the trip planner!
Apologies for the metric units but I live in one of those modern 'international' countries! (Australia)
ElectricTundra
P85D AP1
An EV is massively more sensitive to factors like cargo weight, driving speed, aggressive vs non-aggressive driving, outside temp, wind, and hills than an ICE. This combined with the spacing for SC's (vs a gas station at every exit) creates this need for trip planning. Until there is an SC at every exit we'll likely need to do some level of trip planning for longer trips. The exception perhaps is someone who drives alone with a 20 lb suitcase in 70f weather and at the speed limit (EG, they match Tesla's 300Wh/mile assumptions).
Tesla Nav WILL NOT be able to do this accurately without accounting for those factors above. Presumably it could acquire all of these though not sure how accurate vs asking us to input them as EV Trip Planner does. Perhaps best would be for Tesla to use it's best guess and provide an option for us to correct its guess. It knows current outside temp and can presumably forecast trip temp, wind, and hills fairly easily. Driving speed and aggressiveness can be determined from history. Can it determine cargo weight?
Then it just needs to stop trying to send us back to the supercharger we just visited 160 miles back (and that we can't reach with current charge anyway) when we're sitting in the parking lot of the next supercharger on our trip which 7.1 IS STILL doing!
Tesla Nav WILL NOT be able to do this accurately without accounting for those factors above. Presumably it could acquire all of these though not sure how accurate vs asking us to input them as EV Trip Planner does. Perhaps best would be for Tesla to use it's best guess and provide an option for us to correct its guess. It knows current outside temp and can presumably forecast trip temp, wind, and hills fairly easily. Driving speed and aggressiveness can be determined from history. Can it determine cargo weight?
Then it just needs to stop trying to send us back to the supercharger we just visited 160 miles back (and that we can't reach with current charge anyway) when we're sitting in the parking lot of the next supercharger on our trip which 7.1 IS STILL doing!
in a nutshell, the trip planner can be far less than accurate, unless I am on a road trip I keep it turned off and sometimes you need to shut it down while first leaving a SC stop because if it thinks you don't have enough charge to make the next SC it will try to reroute you, trust your own knowledge of your car's capabilities and plan your trips before setting out in order to have some knowledge of the route. as an aside on my recent trip to CO I was advised by a TMCer that going west on I70 in Kansas requires have at least a 50% buffer to compensate for the elevation changes, the prevalent headwinds off of the rockies and cold temps. another tip when encountering strong headwinds drafting can allow you to drive a lot faster and longer than if you don't draft. I set the TACC at 2 or 3 on open roads and it works out well.
as for the nav's reliabilities I always use waze.
as for the nav's reliabilities I always use waze.
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artsci
Sponsor
As I've said in number of posts: TURN OFF THE TRIP PLANNER!
Problem solved -- it's of no use anyway.
i just completed my first long road trip, SF Bay Area to Park City Utah. 90% of the time I drove at the speed limit or less, which varies from 65 to 80 in some spots, most of it across Nevada was 75. In the warmer flatter areas the energy usage was spot on, but in the colder and / or mountainous stretches I found it under estimated energy usage by 10 to 15 percentage points.
I was using a target of 30% SOC on arrival and in the colder sections, like the original poster, I found the car's projected SOC dropped significantly after the first 10 - 15 minutes. I was dealing with temps as low as 15 degrees and in some areas snow covered roads. Because of the large buffer I planned, the large drop in arrival SOC was easy to manage, I just let it drop until it got to 15% - 20% SOC, then slowed until it stopped dropping or started increasing.
My takeaway has been, around town or in the flatlands with warm tempatures, I'll trust projected 10% - 15% SOC, in bad or cold weather or in the mountains, I'll be carrying additional margins.
Last weekend we used the trip planner for a road trip, typically driving about 5 MPH above the speed limit.
It appears the trip planner gets concerned if the estimated charge at destination is 5% - which doesn't provide a lot of margin for error, so we typically charge at a higher level before leaving the supercharger, to give us a larger margin.
Despite doing that, during the middle leg of the trip, within a few miles of leaving the charger, driving at speed limit+5, the estimated charge at the next charger dropped rapidly. To reverse this, we ended up dropping our speed by 20MPH (15MPH below the speed limit) for almost the entire drive to the next supercharger.
And, it appeared the predominant wind was actually behind us. The temperature was in the 60s and it was sunny - perfect driving conditions. Traffic was light enough that we were able to maintain a constant speed. The drive had some changes in elevation - but they were rolling hills - not going into the mountains. So it was pretty hard to explain why the charge estimate was so far off. And if we'd left the first charger when the trip planner had recommended - we would have had to slow down even further to get to the destination.
I contacted Tesla about this - because clearly their algorithm did something wrong in making the estimate on that one leg of the trip. Their initial response was instructions for displaying the energy graph on the dashboard - and that if I drove at 300 Wh/mi or below, I'd be doing better than rated range.
That advice doesn't really help - because the trip planner isn't using rated range - what you want to see is how you are doing against the trip planner's projection - which can only be done by using up half of the 17" display to show the trip energy chart.
I reported the issue because I hoped Tesla could dump the logs for my trip and look at the weather conditions - and find out why the estimates were so far off for this one segment. Hopefully they'll do that...
The goal for the trip planner is to minimize range anxiety - and let the car's software help plan energy management on the trip - so the driver doesn't have to worry about it. This will be critical as Tesla moves from early adopters to selling higher volumes of their cars. And while the current trip planner is a good start - it needs more work to achieve the goal of reducing range anxiety.
Some specific changes that should be made to the trip planner software:
- Add a setting for projected speed vs. speed limit for planning projections
- Add a setting for desired charge at destination - with the current software 20-25% is probably safe, with better projections 10% should be OK
- Using data from the internet, use more information on the driving conditions to improve the estimates (traffic speed, elevation, temperature, weather, ...)
- Add a setting for the range warning threshold. The software currently warns at 5%, we'd prefer that to be 10% to allow us to slow down earlier
- And, provide an information display with more details on how the projections are being made - so the driver can verify the assumptions the software is using
Plus, they could do so much more with estimating supercharger wait times, but that's another topic...
It appears the trip planner gets concerned if the estimated charge at destination is 5% - which doesn't provide a lot of margin for error, so we typically charge at a higher level before leaving the supercharger, to give us a larger margin.
Despite doing that, during the middle leg of the trip, within a few miles of leaving the charger, driving at speed limit+5, the estimated charge at the next charger dropped rapidly. To reverse this, we ended up dropping our speed by 20MPH (15MPH below the speed limit) for almost the entire drive to the next supercharger.
And, it appeared the predominant wind was actually behind us. The temperature was in the 60s and it was sunny - perfect driving conditions. Traffic was light enough that we were able to maintain a constant speed. The drive had some changes in elevation - but they were rolling hills - not going into the mountains. So it was pretty hard to explain why the charge estimate was so far off. And if we'd left the first charger when the trip planner had recommended - we would have had to slow down even further to get to the destination.
I contacted Tesla about this - because clearly their algorithm did something wrong in making the estimate on that one leg of the trip. Their initial response was instructions for displaying the energy graph on the dashboard - and that if I drove at 300 Wh/mi or below, I'd be doing better than rated range.
That advice doesn't really help - because the trip planner isn't using rated range - what you want to see is how you are doing against the trip planner's projection - which can only be done by using up half of the 17" display to show the trip energy chart.
I reported the issue because I hoped Tesla could dump the logs for my trip and look at the weather conditions - and find out why the estimates were so far off for this one segment. Hopefully they'll do that...
The goal for the trip planner is to minimize range anxiety - and let the car's software help plan energy management on the trip - so the driver doesn't have to worry about it. This will be critical as Tesla moves from early adopters to selling higher volumes of their cars. And while the current trip planner is a good start - it needs more work to achieve the goal of reducing range anxiety.
Some specific changes that should be made to the trip planner software:
- Add a setting for projected speed vs. speed limit for planning projections
- Add a setting for desired charge at destination - with the current software 20-25% is probably safe, with better projections 10% should be OK
- Using data from the internet, use more information on the driving conditions to improve the estimates (traffic speed, elevation, temperature, weather, ...)
- Add a setting for the range warning threshold. The software currently warns at 5%, we'd prefer that to be 10% to allow us to slow down earlier
- And, provide an information display with more details on how the projections are being made - so the driver can verify the assumptions the software is using
Plus, they could do so much more with estimating supercharger wait times, but that's another topic...
Xminus6
Member
Quickly learned some things about this on my last trip from L.A. to Sedona. Wind seems to be the biggest issue by far. Driving through the desert, I could visually see pretty insane winds that I was driving through. The problem is, the car is so dynamic that I barely felt anything. So if you have no idea that you're driving into a headwind or cross wind, you could be in for some serious issues. I would leave a charger with a 30% buffer and show up under 10% consistently during these winds. This is driving between 60-65mph, nothing crazy. If Tesla could work wind into the algorithm I think we'd all be a lot happier.
I just do not see why they cant use google maps, who has billions of miles saved in data, accurate speed tuning / traffic. AND they could plug autopilot in so that it will at least try to stay in the directions you need / slight exits to new highways (not exits to tolls or side roads of course.
I would recommend to supercharge until the planner say at least 20% (the soc when you reach the next supercharger) as absolute bare min. You want some margin of safety anyway if you make a wrong turn, and get into some unexpected situation.
You should put in additional margin of safety to 25 or 30%, if expect any conditions that may require more battery power:
1. the weather is cold, raining, strong wind
2. Your car is very heavy, carrying extra stuff on the roof that increase drag
3. You put on a very high AC or heat,
4. You typically drive much faster than speed limit
5. There is no plan B for any kind of charging along the route
You should put in additional margin of safety to 25 or 30%, if expect any conditions that may require more battery power:
1. the weather is cold, raining, strong wind
2. Your car is very heavy, carrying extra stuff on the roof that increase drag
3. You put on a very high AC or heat,
4. You typically drive much faster than speed limit
5. There is no plan B for any kind of charging along the route
Great suggestions. Got a question, isn't the trip planner accounting for elevation changes since like a year ago?
mikeash
Active Member
Licensing and offline access would be the two major challenges for that, I think. Neither are insurmountable, but I imagine those are the reasons.
It does, yes. When I'm going up into the mountains it will show a steep dip in range on the ascent and then might estimate my return trip to only use 1 - 2% of battery life and it's shockingly accurate.
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In hindsight I wonder if this wasn't a factor. It is generally pretty windy through this stretch. They could easily factor wind or other variables into the calculator by averaging out my recent wh/ mi though. If on the last leg of my trip I was at 350wh/mi in an area it estimates I should have been using 310wh/mi then it should factor that difference into the next leg.
My experience with trip planner is far more positive. It works for me, and works fairly well.
Some of my observations:
1. It doesn't take into account the temperature. If you're driving in below-40-degree weather, ensure you've added appropriate amounts of mileage to cover the gap.
2. It doesn't take into account the winds. You might want to look before you go.
3. It's generally correct at about 0-5 mph above the speed limit for 19" wheels. Also, if you're an aggressive driver that loves to stomp on it, swerve into the other lane, pass, then swerve back, you'll pay for it. If you have 21" wheels, or you aggressively swerve-and-stomp to pass, or you drive faster, you'll need to add accordingly.
4. It does take into account elevation changes -- if you look at the projected line, you'll see where it dips faster than the linear regression would indicate - that's where it expects higher usage; if you see the projected line flatten out more and falls less than the linear regression would indicate, that's downhill.
I use the trip planner as a guideline and make some mental adjustments based on what I know about these factors. In my trip to Florida from Dec 26 - Jan 2, I used the trip planner religiously but gave myself a bit more headroom due to 28 degree temps and winds. I drove just above the speed limit. I did not run into any problems.
Some of my observations:
1. It doesn't take into account the temperature. If you're driving in below-40-degree weather, ensure you've added appropriate amounts of mileage to cover the gap.
2. It doesn't take into account the winds. You might want to look before you go.
3. It's generally correct at about 0-5 mph above the speed limit for 19" wheels. Also, if you're an aggressive driver that loves to stomp on it, swerve into the other lane, pass, then swerve back, you'll pay for it. If you have 21" wheels, or you aggressively swerve-and-stomp to pass, or you drive faster, you'll need to add accordingly.
4. It does take into account elevation changes -- if you look at the projected line, you'll see where it dips faster than the linear regression would indicate - that's where it expects higher usage; if you see the projected line flatten out more and falls less than the linear regression would indicate, that's downhill.
I use the trip planner as a guideline and make some mental adjustments based on what I know about these factors. In my trip to Florida from Dec 26 - Jan 2, I used the trip planner religiously but gave myself a bit more headroom due to 28 degree temps and winds. I drove just above the speed limit. I did not run into any problems.
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