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

[ℬête Noire]

Autopilot user I assume. That is a factor here: you can usually spend more time on the road without needing to stop because you are tired.

Autopilot is huge. Having traveled with it now I expect I'd have a very hard time to returning driving long distance without out it. I use fairly extensively locally but I could easily give that up. It's nice, makes slow moving and/or very heavy traffic a lot less stressful and tedious. For anything over 2 hours on the highway, though, it leaves you physically and mentally in so much better shape during and at the end of the trip.

I mentioned prior a 1600 mile trip. Specifically it was Adrmore, OK to Warren, NJ via Nashville, TN route. A hair under 1600 miles, in 32.5 hours total time. That was including some non-trip related stuff and also a rookie oppsie on my part in the first leg**. That's one driver plus a passenger. Power napped in a couple places, temps across the trip ranging starting out in the low 30's up to the low 50's.

The only meaningful stretch eastbound I drove manual was some of the upslope and nearly all the extended downslope sections coming out of Nashville area. The road was wet in places, there was light fog shifting in and out, and I felt more comfortable being full manual incase of weirdness. On return Birmingham to Jackson was very heavy rain, I used a mix of EAP, TACC and full manual there. Pretty much everything else was EAP. It saves so much longterm exertion on you arms, and eyestrain flipping close-up to long vision I suspect, along with brain activity.

I could have done better on time, maybe hit that 50mph total trip average. Really it took me until into TN to find the rhythm of SC hopping, as I was trying out different approaches to see what really worked in real world. At the end though I sat down at a family friends' place for a light supper catching up with them, then caught a train into NY and finally checked in around midnight. Without any of the normal wrung-out, thousand-yard-stare feeling I've always experienced with prior drives of this sort of nature.

That's a 48mph average, including overnight sleeping, on the way out. Not as good on the way back but that's because I started out late day and checked into a hotel fairly early in the trip. Phenomenal. I've hit that before with ICE but only being very on-point with methodology (diet, bio-breaks, no passenger, planned out, etc) in optimal weather, and being hit for near a day afterward recovering from the wrung-out toll. I played this very loose, I hadn't even chosen the major route I'd take until the morning of, and just played it as it went using the car's nav to guide it.


** The battery was cold soaked from freezing temps the prior night, with no plug-in, and I rushed out of the slow charging in Ardmore SC, not letting the car get the safety padding it wanted. I would have "made it" but it was very tight and I needed to slow down enough that I decided I might as well pull into an L2 anyway, run out of the back of an insurance office by a really nice 2015 Model S owner. That probably cost me 1/2 hour...by the time I got done talking with the Tesla owner.

 

[Evbwcaer]

Here is my "equation," and it factors in all factors (wind, temp, elevation). To make the trip as fast as possible: Drive as fast as you can without getting pulled over AND not consuming electricity at a rate faster than your chargers can supply it.

If you are using 20kw while headed to a charger than can only supply 10kw, you should slow down, if looking to minimize total time.

 

[Petrlol]

i wonder why no one talks about EVTripPlanner anymore..

for me it's the gold standard.

So I've never used this before, but was this a sarcasm post???

I put in the speed multiplier, exterior temp 25f, interior 68f, and a drive that I've personally done multiple times. It says I'd average 248 Wh... which is not even close at all!

BRP says 295, and the times I've actually driven it I've come back between 290 and 305. Using EVTripPlanner I would have been stranded assuming I was going to pull 248.

Is it perhaps the exterior temperature they're not calculating correctly?

 

[ModelNforNerd]

So I've never used this before, but was this a sarcasm post???

I put in the speed multiplier, exterior temp 25f, interior 68f, and a drive that I've personally done multiple times. It says I'd average 248 Wh... which is not even close at all!

BRP says 295, and the times I've actually driven it I've come back between 290 and 305. Using EVTripPlanner I would have been stranded assuming I was going to pull 248.

Is it perhaps the exterior temperature they're not calculating correctly?

I believe it's because ABRP accounts for elevation, whereas EVTT may not.

 

[Big Earl]

That particular item is because it is the upside down of the way it works. You assume fast and it tells you when you need to slow down. Also, it appears that the nav does use some of the other factors (I'm talking the car, not the www.Tesla.com trip planner) directly and some of it indirectly.

I found that the more I drive the better it gets, I suspect it is filling in that stuff with actual use data, 100% it is using current battery state. It shows me where I could go and then I do a translation to shorter hops for speed (and less fatigue by keeping per stop under 2.5hrs). As a bonus it also includes DC locations and gives warnings when you'll be stuck if you don't have a non-DC/SC option available to you.

Better Route Planner is just flat out too conservative I've found. It adds huge chunks of unnecessary time ad distance because it can't find viable routes. The only way I can coax it to make jumps the car is perfectly capable of doing is put in gonzo efficiency numbers, pin the max-min to 0-100. At that point I've lost confidence in it's output.

BRP probably ok to use in very dense SC, where it's easier to find a good enough route. But out here in the middle of the continent it comes up short.

I'm surprised by your problems with ABRP, as I've had nothing but good results with it on numerous long road trips, including trips where the Supercharging infrastructure isn't very dense. I've found that I had to bump up its estimated consumption figure from 247 Wh/mi to 265 Wh/mi in the winter time, but after that little tweak, it's been very accurate, particularly when accounting for wind. Its trip time estimates have been spot-on, even on longer 12-hour trips with 5 charging stops.

That said, it isn't gospel and I use it as a general guide for a road trip. Once I'm actually in the car, I plug in each Supercharger location into the car's navigation instead of plugging in my destination and letting the car figure out the charging stops.

Keep in mind that while the car can certainly stretch its legs and skip Superchargers, this is not the fastest way to get where you're going. ABRP's focus is on the shortest trip possible, which often involves more Supercharger stops, but with less time spent charging at each one.

 

[ℬête Noire]

That said, it isn't gospel and I use it as a general guide for a road trip. Once I'm actually in the car, I plug in each Supercharger location into the car's navigation instead of plugging in my destination and letting the car figure out the charging stops.

This is pretty much my point, with the caveat of weather fudge factors if you're really pushing the edge and also include extra SC if they're right on the route because they'll let you keep the charging near the top of the kW curve. Get in the car and drive, work it out on the way.

ABRP's focus is on the shortest trip possible, which often involves more Supercharger stops, but with less time spent charging at each one.

But that is NOT the case. There are other examples that are more subtle, but what makes this so starkly clear is plug in Houston to Calgary. ABRP adds nearly a day to what the car sees (and what you can verify by hand with a calculator and empirical data if you're so inclined). The car knows it can make from Montana to Fort McLeod, AB without going through Idaho and BC. In the not-Winter even without going via Whitefish, though that's tighter for the trade-off of saving 40 miles or so.

((There's a DC in St. Helena that probably allows the uphill North-South direction in the summer, too, without going via Whitefish. I don't know if the car nav fully understands that, though I know to some extent it knows about the DCs because it uses them as a factor before throwing up the "if you don't change your route you'll never get out of here" warning. ))

P.S. Tesla.com is worse, it adds a full day plus because it'll send you all the way out to the BC lower mainland.

 

[Galve2000]

So I've never used this before, but was this a sarcasm post???

not sarcasm at all.

but i'd be careful with the speed multiplier settings. i'm a "10 over" kind of guy and I think that Is already baked into the google and EVTripPlanner results. so I keep the multiplier to 1.0

also.. as superchargers have proliferated, we have a lot more options with where and when to stop and I don't know that the algorithms are optimized for this. so I often make my own path. even if it means stopping at more SCers along the way.

where I may differ from most of you, however, is that I don't often wake up in the morning w\ a full ((0% battery) so an early stop along the way is usually how I have to roll.. although it drives me nuts that EVTripPlanner will always chose the closest SC to my home as a means of topping up.

its an easy fix tho.. just delete it, and have EVTripPlanner "route directly" without it.

 

[Dana1]

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.

Mathematically you’re setting up a multi factor model. You need the beta values for each of your factors...that’s the tricky part. It would need a straight road, say 50 miles, driven at each temperature point at each speed point to produce the curves. The speed curve isn’t linear but if you drive the stretch in 5 mph increments you’ll get the idea...think Black Scholes type stuff. There’s probably already wind vs speed curves close enough to 3’s body type. What you’re proposing would take some time to be really detailed about it.

 

[garu]

I noticed that when I drive at 80~85 MPH on road trips, I need to charge for longer because the battery depletes faster. Has anyone done the math to figure out whats the best speed to minimize charging time while not being too slow?

 

[ucmndd]

It's almost always fastest to drive as quickly as you want.

Minimize charging time by working the lower range of your battery when supercharging is fastest. You'll sometimes find more frequent stops actually SAVE time vs. trying to skip a charger but needing to top off to 90 or 100%.

 

[AlanSubie4Life]

I noticed that when I drive at 80~85 MPH on road trips, I need to charge for longer because the battery depletes faster. Has anyone done the math to figure out whats the best speed to minimize charging time while not being too slow?

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

Credit to @Daniel in SD

Note the assumptions may need to be changed now (charge rate specifically), and the full taper profile, travel time to get to the Supercharger, etc., are not included in this calculation. The consumption numbers are a little off too, since only a portion of the consumption scales with the square of velocity. But it could be relatively easily made more sophisticated.

The point is that going fast is very likely faster, as long as you can make it.

On my road trip I just tried to keep it at 80-83mph when possible, but average moving speeds ended up closer to 65mph (there was a fair amount of driving off the interstate so 80mph was not acceptable - fastest leg was 73mph). Ended up averaging around 300Wh/mi round trip. Seemed to be pretty efficient time-wise. 18.5 hours driving, 2.7 hours charging (there was room for cutting that to closer to 2.25 hours I think).

 

[Bears249]

Most people here will yell at you and say if you want better mileage drive 65. I find 72 is a nice happy medium. I usually get around 265-280 wh/mile with AP on running either heat or AC. It occasionally jumps up to 305 or so if the road is slightly inclined.
P3D-

 

[1.21GW]

 

[Gondi63]

The point is that going fast is very likely faster, as long as you can make it.

Makes a lot of sense when you think about how fast we can charge at SC. If you're charging at 500mph, might as well burn electrons as fast as possible.

 

[Daniel in SD]

This team averaged 72mph (including charging) by driving about 107mph and using CCS chargers. V3 would be a little faster.
Tesla Model 3 Breaks EV Distance Record In 24-Hour Run: Video

 

[Silicon Desert]

It's almost always fastest to drive as quickly as you want.

Minimize charging time by working the lower range of your battery when supercharging is fastest. You'll sometimes find more frequent stops actually SAVE time vs. trying to skip a charger but needing to top off to 90 or 100%.

yup, that's been my experience.

 

[SageBrush]

Here is my "equation," and it factors in all factors (wind, temp, elevation). To make the trip as fast as possible: Drive as fast as you can without getting pulled over AND not consuming electricity at a rate faster than your chargers can supply it.

If you are using 20kw while headed to a charger than can only supply 10kw, you should slow down, if looking to minimize total time.

At the limit then where car power = charging power you are spending as much time charging as driving and your average speed is 1/2 of your driving speed.

 

[adamtc4]

Here are some simple rules.
Start with a 100% from your starting point and make it as far as possible to your first supercharge stop. Studies found that driving around 90mph was the optimal speed for a Tesla roadtrip but most people aren't comfortable doing that so 75-80 should be fine. Try to stop with about 10% battery and charge to 50% (This will give you the maximum amount of battery in the quickest time, doesn't make sense to stop charging before you hit 50%) at this point check to see where the next superchargers are on your route. If you can charge a few more minutes and get 2 to 3 superchargers away then perfect. If not, then just go to the next charger available. Works for me.

 

[jerry33]

Here are some simple rules.
Start with a 100% from your starting point and make it as far as possible to your first supercharge stop. Studies found that driving around 90mph was the optimal speed for a Tesla roadtrip but most people aren't comfortable doing that so 75-80 should be fine. Try to stop with about 10% battery and charge to 50% (This will give you the maximum amount of battery in the quickest time, doesn't make sense to stop charging before you hit 50%) at this point check to see where the next superchargers are on your route. If you can charge a few more minutes and get 2 to 3 superchargers away then perfect. If not, then just go to the next charger available. Works for me.

This method only works if you are in a Supercharger rich environment (CA or East Coast). If you are in the middle, you charge for about 15 minutes at each stop to get enough charge to go to the next one. In my experience, this is no different than driving a gas car because stopping about every 100-150 miles would be required even if it was a 10,000 mile battery.

 

[KenC]

So, you piqued my interest. Maybe, the answer is in the first 3 pages, but I did a simulation on ABRP.

In order for me to travel from Maine to visit my brother in LA, I'd have to travel 3200 miles, and if I set my speed at:
Speed, SC time, driving time, TOTAL time
65mph, 7:11, 48:42, 55:54
70mph, 7:50, 45:10, 53:01
75mph, 8:36, 42:27, 51:04
80mph, 9:39, 39:41, 49:21
85mph, 10:18, 38:13, 48:32
90mph, 10:26, 37:27, 47:54
95mph, 10:39, 36:50, 47:30

So, even at 95mph, it seems that the increase in charging time, is not enough to offset the savings in driving time, so you continue to save total time, the faster you drive. Interesting.