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Super Charger Route Planning - Why Not Max Out at Fastest Chargers

Hello!

Ordered my model Y and super excited to receive. :) This will be our first EV and I've been watching lots of YouTube about EV's in general and taking the Tesla on a road trips. In regards to planning the supercharger stops, I've seen this behavior several times on the videos, and just now playing around with the A Better Route Planner website. Hoping someone can explain the logic.

For example, I planned a 370 mile trip from Redmond, WA to Bend, OR via Yakima, WA. The website has me making two stops along the way.
Leave: 90% battery charge
Stop 1: 8 minutes in Yakima to charge from 27% to 53% on a 250kW charger
Stop 2: 22 minutes in Dalles to charge from 10% to 71% on a 150kW charger
Arrive: 10% battery charge

Why not charge back to 90% at the first stop with the faster 250kW charger? Then arrive at the second slower 150kW charger with more battery, and require less time to charge up to the needed 71% to complete the trip?

In general when on a long road trip, when already stopped, why not always charge up to 90% when at the fastest supercharging stations?

Thanks!
Jason
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
7,008
13,891
Springfield, VA
Hello!

Ordered my model Y and super excited to receive. :) This will be our first EV and I've been watching lots of YouTube about EV's in general and taking the Tesla on a road trips. In regards to planning the supercharger stops, I've seen this behavior several times on the videos, and just now playing around with the A Better Route Planner website. Hoping someone can explain the logic.

For example, I planned a 370 mile trip from Redmond, WA to Bend, OR via Yakima, WA. The website has me making two stops along the way.
Leave: 90% battery charge
Stop 1: 8 minutes in Yakima to charge from 27% to 53% on a 250kW charger
Stop 2: 22 minutes in Dalles to charge from 10% to 71% on a 150kW charger
Arrive: 10% battery charge

Why not charge back to 90% at the first stop with the faster 250kW charger? Then arrive at the second slower 150kW charger with more battery, and require less time to charge up to the needed 71% to complete the trip?

In general when on a long road trip, when already stopped, why not always charge up to 90% when at the fastest supercharging stations?

Thanks!
Jason

150 kW and 250 kW stations charge at about the same speed above 50%. ABRP's recommendation seems pretty solid to me.
 
The charge rate drops as the battery fills. At a V3 Supercharger the time to get from 80% to 90% is something like 5x longer than the time from 20% to 30%. This effect is true for all lithium-ion batteries, although the exact numbers vary a bit.

You can try it on ABRP, by the way. On the list of stops (after clicking "back" until there is no "back" button), click the cog wheel at the first stop, and enter 90% in the "charge to" field. It should then eliminate the second stop, but you'll see how long it takes at the first one. The total time will be longer.

Edited to add a graph of charging rate vs charge state. It's for a Model 3, but the Y is basically the same.
1619637126045.png
 
A lot of useful information here, but here is another thread with a lot of detail too:


It confused me at first too, but after I thought about it, charging the minimum required to make it to the next charger is the most efficient way to travel once you factor in the rate of charge decreases with increased state of charge. Obviously if you think you may need more SoC once you reach your destination, you can adjust accordingly.
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
7,008
13,891
Springfield, VA
I charged at a 72Kw yesterday and it was charging at 38Kw,(24 stalls only about 8 filled, none near me). I reconnected, could have been the cable itself but charging varies for sure.

If you ever end up at a stall that seems unreasonably slow, it's best to move to a different one. Sometimes a charger, connector or cable will have problems that causes slow charging.
 
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drtimhill

Active Member
Apr 25, 2019
3,075
4,011
Seattle
Hello!

Ordered my model Y and super excited to receive. :) This will be our first EV and I've been watching lots of YouTube about EV's in general and taking the Tesla on a road trips. In regards to planning the supercharger stops, I've seen this behavior several times on the videos, and just now playing around with the A Better Route Planner website. Hoping someone can explain the logic.

For example, I planned a 370 mile trip from Redmond, WA to Bend, OR via Yakima, WA. The website has me making two stops along the way.
Leave: 90% battery charge
Stop 1: 8 minutes in Yakima to charge from 27% to 53% on a 250kW charger
Stop 2: 22 minutes in Dalles to charge from 10% to 71% on a 150kW charger
Arrive: 10% battery charge

Why not charge back to 90% at the first stop with the faster 250kW charger? Then arrive at the second slower 150kW charger with more battery, and require less time to charge up to the needed 71% to complete the trip?

In general when on a long road trip, when already stopped, why not always charge up to 90% when at the fastest supercharging stations?

Thanks!
Jason

As others have noted, charging rates are non-linear. ABRP is optimizing for minimum time spent charging by keeping the battery in the "fastest charging" bands. One stop with a "deeper" charge would add up to a longer total time. Of course, you are free to use that strategy if you would prefer just one longer stop.
 
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1) WOW! I posted the message and left for lunch. I was hoping maybe I would get 1 reply. Instead an out pouring of really good information. Thanks everyone!
2) This makes total sense now! I didn't realize the charge rate dropped off so drastically as you charged the battery. You really only see those top charge rates when the battery has a relatively low charge left. I'll investigate further, but does this mean that (in really general terms) the lower the superchargers max rate, the longer you actually get time at that top rate? For example, maybe a 250kW starts dropping power at 25%, while a 150kW will stay at it's max until 50% battery, and a 50kW would stay maxed out to nearly 80% charge?
3) Feathermerchan, yeah I was just playing to get a feel for what that trip would look like from a charging perspective. I assume I can tell the website I want to arrive with 20% or 30% and it will re-optimize my stops. Cool stuff, and fun wrapping my head around a new way to travel. I obviously am still holding on to the "gas" mentality where you fill up the tank at every stop regardless. I see now the same rules don't apply to EV charging.

Thanks everyone!
 
Shocked - You can use ABRP to determine your desired charge level to return.
You can also look at the bottom of the turn-by-turn list and it will show you the round trip charge state. Just charge until that reaches 15% or so and you'll be good. You may want to wait until you get to the last SC stop then cancel mav and restart it from there so it shows the return to that SC. Then charge until the return level is 10-15% and you'll be fine.
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,941
10,060
Boise, ID
This makes total sense now! I didn't realize the charge rate dropped off so drastically as you charged the battery. You really only see those top charge rates when the battery has a relatively low charge left. I'll investigate further, but does this mean that (in really general terms) the lower the superchargers max rate, the longer you actually get time at that top rate? For example, maybe a 250kW starts dropping power at 25%, while a 150kW will stay at it's max until 50% battery, and a 50kW would stay maxed out to nearly 80% charge?
Well...kind of, yeah, but I think you may be perceiving this wrong, as if the lower power ones are somehow doing better. The tapering of the charging power level is determined by the car's battery. So even if a station can provide some higher number, it's still going to throttle down to whatever the car is going to allow. So if the car is saying in that moment that I can only handle a maximum of 102kW or something, the Superchargers that could output 150 or 250kW will still act exactly the same and provide that 102kW, because that's all the car is requesting, because that's all it can safely handle at that point. But sure, you could say that a 50kW charger would be sending all it can do until the car's tapering curve comes down to 50kW or less, which would be up at a higher state of battery level.
 
Well...kind of, yeah, but I think you may be perceiving this wrong, as if the lower power ones are somehow doing better. The tapering of the charging power level is determined by the car's battery. So even if a station can provide some higher number, it's still going to throttle down to whatever the car is going to allow. So if the car is saying in that moment that I can only handle a maximum of 102kW or something, the Superchargers that could output 150 or 250kW will still act exactly the same and provide that 102kW, because that's all the car is requesting, because that's all it can safely handle at that point. But sure, you could say that a 50kW charger would be sending all it can do until the car's tapering curve comes down to 50kW or less, which would be up at a higher state of battery level.
Yep, exactly. If I'm going to be charging when already at 50% battery, there is no reason to seek out a 250kW charger. A 150kW would give the same charge time.
 
While I do use ABRP for planning, it usually takes me a bit longer during a charging stop. The wife, kids, dogs all get out and then all have to be herded back into the car. Plus I now need to stretch my legs a bit more than when I was 20. I used the ABRP plan as a guide, to make sure I get above what the plan recommended. I also set my charging level to 99% for trips, although I have never reached that since I'm ready to go before it gets to that level.
Depending on how long I stayed, I then set up the Nav system to head to the destination and do a quick look at what % I am expected to arrive at the next SC. I also make sure that I then set the next SC as the destination so that the batteries get warmed up as we arrive.
 
I am also making sure that folks see this other thread.
Something we all need to be aware of. At least I know I'll be a bit more careful about checking the plug.
 
I've used ABRP on a number of long (and short) trips. Found it to be pretty accurate.
One other tip not mentioned here is setting the "Settings" to correspond to your car and the particulars of the trip.
I found that ABRP used 290wh/mi for my MY. In reality I have been averaging 250 now that the weather is warmer.
The weather/winds/weight will also impact the accuracy. You can adjust these as it pertains to your situation/trip. You need to flip the "details" switch at the top of the settings page to access these numbers.
 
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Pianewman

2021 MYLR VIN 88,XXX, Rd/Wh, 12/20 delivery
Supporting Member
Oct 28, 2020
2,131
1,764
Fort Worth
I've used ABRP on a number of long (and short) trips. Found it to be pretty accurate.
One other tip not mentioned here is setting the "Settings" to correspond to your car and the particulars of the trip.
I found that ABRP used 290wh/mi for my MY. In reality I have been averaging 250 now that the weather is warmer.
The weather/winds/weight will also impact the accuracy. You can adjust these as it pertains to your situation/trip. You need to flip the "details" switch at the top of the settings page to access these numbers.
If it were me, I'd leave the ABRP setting alone, and in fact, will probably keep my setting around 300wh/mi, although my 4k mile lifetime average is 275wh/mi.
 
That's the point of having it adjustable. Depending on your circumstances, ABRP can be customized nicely. I set my wh/mi at 275 just for piece of mind. I did a bunch of drives with ABRP doing the planning and confirmed my expectations. You should also before heading out.

ABRP allows weight adjustments, in case you're fully loaded. Rainy weather - that's adjustable also.
 
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