Road trip math - how fast to drive, how long to charge

[Mod3forMe]

I was thinking about putting together the calculations on the optimum way to plan road chip charging and highway speeds. Before I do I am wondering if someone has already tackled this? If not I am also wondering were I can find the key data points?

The key thing I would like to figure out is how fast to drive on highway road trips. If I can nail down the average power consumption and different highway speeds and the average charge times, I can come up with calculations that tell you wether you will save more time by driving fast and charging longer or driving slow and charging less.

 

[CCIE]

Check out "a better route planner" online. It should do all of that for you.

 

[Galve2000]

Stick to 70 mph if you can...

if you get a speeding ticket, the math goes out the window.

with charging/use of the facilities breaks the old average used by truckers of 50 mph for the average speed of a long distance trip is what you want to aim for.

i personally like to keep a 30% buffer in my battery for more spirited driving. particularly in winter. 20% is spring/summer/fall.

in most of my road trips I end up charging to more range than i originally intend to b/c the car is always done charging b4 i'm ready to keep driving..so i will always let it charge to 90% even tho I meant to charge only to 60% + a buffer (as an example) -- b/c the car is already at a charger.. why not let it do it's thing...

 

[zer0cool]

There are too many variables such as speed, temperature, other weather conditions, altitude, etc. Overall the estimate by the GPS is a good starting point. The close to optimal way is to get to the next must-visit SC with about 10% charge remaining (assuming you get anxiety if it falls below that, also need to leave some margin for unexpected traffic). Then from time to time on your drive watch the energy chart and see if you are above or below the curve and adjust your speed accordingly to match the estimated curve. Then you would arrive with about 10% remaining so you can charge quickly back to whatever % you need to get to where you next need to go.

The idea is to start charging from a low state of charge since charging is MUCH MUCH faster (in terms of miles per time) at that point.

 

[e-FTW]

There are too many variables such as speed, temperature, other weather conditions, altitude, etc. Overall the estimate by the GPS is a good starting point. The close to optimal way is to get to the next must-visit SC with about 10% charge remaining (assuming you get anxiety if it falls below that, also need to leave some margin for unexpected traffic). Then from time to time on your drive watch the energy chart and see if you are above or below the curve and adjust your speed accordingly to match the estimated curve. Then you would arrive with about 10% remaining so you can charge quickly back to whatever % you need to get to where you next need to go.

The idea is to start charging from a low state of charge since charging is MUCH MUCH faster (in terms of miles per time) at that point.

Yup. Leave with a full battery and make it to the farthest Supercharger you can.
Then charge just enough to get to the next one and so on (assuming you are on a long trip, and not facing a constellation of SCs like in California).
If you have destination charging, aim to arrive with a low charge, or depending on the speed of the charging options at your destination, enough charge so that you can charge to 100% by the time you leave the next morning.
But as @Galve2000 mentioned, that plan does not always work perfectly as oftentimes, the car will be ready before you are. Which means you get to skip the next SC and drive further.
They key is that humans mess up all the calculations with our need for sustenance and unfolding our legs regularly.
Humans and weather actually.

The energy graph really is your best friend. Keep an eye on it, and just your speed accordingly. It is pretty darn good.
Where are you going? What is your route?

 

[trunks13]

I had range/supercharger anxiety for a planned long road trip from OC to NorCal during the holidays. Ended up taking my ICE car as I didn't want to risk it during the holidays. Can anyone comment on supercharger availability along I-5? Was there a good wait or were there stalls available?

TIA.

 

[TT97]

I had range/supercharger anxiety for a planned long road trip from OC to NorCal during the holidays. Ended up taking my ICE car as I didn't want to risk it during the holidays. Can anyone comment on supercharger availability along I-5? Was there a good wait or were there stalls available?

TIA.

From what I have read, Kettleman City had a wait during some times but with 40 stalls, the waits weren't long. I didn't hear about waits at other locations. The busier locations had attendants to maintain organization and there were "40 minute" charging limits posted.

Kettleman City thread had some comments on the availability:

Supercharger - Kettleman City (LIVE 15 Nov 2017, 40 stalls and a lounge)

 

[Trips]

There are too many variables such as speed, temperature, other weather conditions, altitude, etc. Overall the estimate by the GPS is a good starting point. The close to optimal way is to get to the next must-visit SC with about 10% charge remaining (assuming you get anxiety if it falls below that, also need to leave some margin for unexpected traffic). Then from time to time on your drive watch the energy chart and see if you are above or below the curve and adjust your speed accordingly to match the estimated curve. Then you would arrive with about 10% remaining so you can charge quickly back to whatever % you need to get to where you next need to go.

The idea is to start charging from a low state of charge since charging is MUCH MUCH faster (in terms of miles per time) at that point.

Abetterrouteplanner.com does look at Speed, Outside Temp, Wind, Road Conditions (Dry, Rain/Snow, Heavy Rain/Snow), Weight, Battery Degradation, Time to Open Charge Port. You can also adjust your minimum amount that you want to arrive at a charger with. It is the best site for longer trips.

 

[ℬête Noire]

Check out "a better route planner" online. It should do all of that for you.

I have found its output questionable.

 

[ℬête Noire]

I was thinking about putting together the calculations on the optimum way to plan road chip charging and highway speeds. Before I do I am wondering if someone has already tackled this? If not I am also wondering were I can find the key data points?

The key thing I would like to figure out is how fast to drive on highway road trips. If I can nail down the average power consumption and different highway speeds and the average charge times, I can come up with calculations that tell you wether you will save more time by driving fast and charging longer or driving slow and charging less.

There is a lot of variables at play for the detiails, but as long as you're following the SC network path itself you'll never travel faster than at the posted speed limit, without exceeding that speed limit.

Maximum safe speed is almost ways the answer, but that's mostly because traveling with ambient traffic is generally the safest speed to be travelling. Moving with traffic, rather than slower or faster, provides a lot of benefit in reducing the air drag for the Model 3.

 

[ℬête Noire]

Yup. Leave with a full battery and make it to the farthest Supercharger you can.

Not if total travel time is your concern. 10%-70% is the sweet spot for charging. Depending on the area, you can hit every SC and most of your. This helps you keep feeling fresh. When you're potentially getting into fatigue area you can power nap for a 90% full charge and then power nap/camp/hotel wherever you've gotten where you're alertness is in question, and not have to worry about Camper Mode running you out of charge to get to your next stop.

Have hit very close to 50mph all-inclusive for 1600 mile trip this way, and that was with a teenage passenger. Non-driver co-pilots can help with doing searches w/o stopping and so on, but ultimately they always slow you down because now you have to time multiple bio-breaks. A co-driver on the other hand can make it very easy to hit > 50mph.

 

[CCIE]

I have found its output questionable.

It’s using math... garbage-in, garbage-out. Check the advanced settings and assumptions.

 

[Petrlol]

I have found its output questionable.

Any examples? My trips have been within a few % if I actually enter the right starting parameters

 

[ℬête Noire]

It’s using math... garbage-in, garbage-out. Check the advanced settings and assumptions.

That’s part of the problem. Seems to be garbage assumptions somewhere in the algorithms. The biggest issue is long gaps that the car itself knows it can do & website says it can’t unless you put in nonsense numbers.

 

[Daniel in SD]

Playing around with a better route planner on the route from San Diego to Seattle. Setting reference speed to 200% and max speed to 118mph gets the fastest time of 17:40 (average speed 73mph, average moving speed 103mph, 5 hours of charging time). It doesn't look like it's doing it optimally though. It's charging to 96% at one of the superchargers. They don't have a way to set max charge percentage which would probably get you closer to the true optimum. My guess is that charging to about 70% and driving 120mph or as slow as necessary to get to the next supercharger empty is optimal.

 

[ℬête Noire]

I will say Better Route Planner is about as good as there is outside the car itself. But it isn’t as good as the car at estimates. The one thing it has over the car is you can have waypoints & try plan where you aren’t. But then if you’re that far out you don’t likely have hard weather data.

The car has issues, too. It likes longer leaps a bit too much for “fastest”. I think it’s because it’s really pessimistic about short, low SOC charge times. That might be correct assumption in areas where SC are heavily subscribed, but it runs w/that all the time.

But excepting having traffic breaking wake for you, it is uncanny about arrival SOC estimates UNLESS you start using the cabin heat part way. Then initial estimate is out & you better listen to its new recommendation about speed.

 

[boiler81]

I will say Better Route Planner is about as good as there is outside the car itself. But it isn’t as good as the car at estimates

Are you referring to the "real time" trip consumption graph estimate, or the navigation estimate? I've not found the Navigation system estimate to be as good as the Better Route Planner, as the car's initial navigation estimate doesn't factor in temp, road conditions, excess vehicle weight, HVAC consumption, driving above posted limits, etc.

I've found that the Better route planner is pretty good, if you enter all the advanced settings accurately.

 

[Knightshade]

Are you referring to the "real time" trip consumption graph estimate, or the navigation estimate? I've not found the Navigation system estimate to be as good as the Better Route Planner, as the car's initial navigation estimate doesn't factor in temp, road conditions, excess vehicle weight, HVAC consumption, driving above posted limits, etc.

I've found that the Better route planner is pretty good, if you enter all the advanced settings accurately.

Same here- BRP > Car planner if you take the time to put correct data into BRP.

 

[Mod3forMe]

Check out "a better route planner" online. It should do all of that for you.

It does not really produce what I want. I want to figure how to travel a certain distance in the shortest possible driving/charging time.

Let's say I have route with SC perfectly 200 miles apart.

If I drive 55mph it will take 3hr38min between chargers
If I drive 60mph it will take 3hr20min
If I drive 65mph it will take 3hr5min
If I drive 70mph it will take 2hr51min
etc.

The faster you drive, the more time you save (duh) simple on an ICE as refuelling times are not much different from pumping 2 gallons vs 10 gallons.

But with an EV the next part of the puzzle is figure out power used per mile at the different speeds and charging times to replace the power and of course if I have enough power to drive that fast and still make it 200miles.

The chart below gives me some idea of what this is (for the model S). Then you need to mix in charge rate times.

If you crunched all these numbers you would end up with the ideal speed to drive and charging time combination.

 

[e-FTW]

Not if total travel time is your concern. 10%-70% is the sweet spot for charging

I meant leave at 100% at the beginning of your trip. Like from your home.