# What's the best practice for a round trip drive?



## Doug Crow (Aug 7, 2018)

So say you are going to make a round trip to the big city, about 104 miles away. The elevation of this city is a little higher and there is also a mountainous area between you and it so you climb about 3,000ft going up and descend about 2,000ft (and descend about 3,000ft and climb about 2,000ft coming back). In light of that you could employ one of two charging strategies for best battery longevity and wear and tear.

Scenario 1:
You charge to 100%, get to your destination with about 51% and then arrive home with about 13% using less energy on the return trip as it is more downhill. You have fully charged and deep cycled the battery, but not supercharged. 

or

Scenario 2:
You depart with 90% charge and supercharge either at your destination, or at a charger on the way home, never going below 30%. You have supercharged, which is harder on the battery, but you've avoided fully charging, or deep cycling the battery. 

This is a round trip I will probably be making on average of once a month, so knowing which practice is best for the battery would be helpful.


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## Bigriver (Jan 26, 2018)

The battery simply isn’t that fragile. Both options are well within what it is designed for. I don’t think you would have any appreciable stress on the battery for either scenario.


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## TrevP (Oct 20, 2015)

The battery in the Model 3 is pretty much bullet proof. Don’t overthink it, trust the trip computer estimate and charge when you can


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## garsh (Apr 4, 2016)

Doug Crow said:


> Scenario 1:
> You charge to 100%, get to your destination with about 51% and then arrive home with about 13% using less energy on the return trip as it is more downhill. You have fully charged and deep cycled the battery, but not supercharged.


Personally, this is what I would do. I'd try to avoid the extra charging stop (unless I had free supercharging - I have a hard time passing up a good deal  ).

I would time the charging to reach close to 100% right as I'm leaving so that the battery doesn't sit at that level any longer than necessary.
But also keep in mind that you lose most of your regen at 100%, so if you begin your journey downhill, that wouldn't be ideal.

Also, if you encounter bad weather on a particular day, efficiency will suffer and you'll probably have to charge in the middle of the trip anyhow.


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## Doug Crow (Aug 7, 2018)

garsh said:


> Personally, this is what I would do. I'd try to avoid the extra charging stop (unless I had free supercharging - I have a hard time passing up a good deal  ).
> 
> I would time the charging to reach close to 100% right as I'm leaving so that the battery doesn't sit at that level any longer than necessary.
> But also keep in mind that you lose most of your regen at 100%, so if you begin your journey downhill, that wouldn't be ideal.
> ...


Indeed, whenever I charge to 100% I try to leave within a half hour of it getting to that state. I'll probably do this in the future, skip the charging stop.


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## Bigriver (Jan 26, 2018)

@Doug Crow, I'm curious if the stats you quoted are winter, summer or somewhere in between? I also have a trip I do with great regularity, so am very aware of the variability in the efficiency. Even for seemingly similar situations (same outside temp and no precipitation), I get notable variations that I have attributed to wind. Therefore my starting out plan is never to go below 10% SOC, keeping at least that much as a buffer.


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## Doug Crow (Aug 7, 2018)

Bigriver said:


> @Doug Crow, I'm curious if the stats you quoted are winter, summer or somewhere in between? I also have a trip I do with great regularity, so am very aware of the variability in the efficiency. Even for seemingly similar situations (same outside temp and no precipitation), I get notable variations that I have attributed to wind. Therefore my starting out plan is never to go below 10% SOC, keeping at least that much as a buffer.


This was kinda in-between, temps during that drive probably ranged from low 40s to low 60s, no precipitation. Obviously if it's colder or rainy I may have to adjust a bit.


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## garsh (Apr 4, 2016)

Bigriver said:


> Therefore my starting out plan is never to go below 10% SOC, keeping at least that much as a buffer.


Ten percent buffer? Fa! Amateur.


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## Bigriver (Jan 26, 2018)

garsh said:


> Ten percent buffer? Fa! Amateur


As already well established, you're insane!!

My closest call was when I had a brain fart and somewhat mindlessly passed the Strongsville exit on the Ohio turnpike with 29 rated miles left. Turnpikes aren't a good place to do that as the next exit is sometimes a bit far away. Luckily next exit and supercharger weren't too bad.... 20 miles. I slowed to 65 mph and turned off a/c. Teslafi data tells me it was 94 F in the cabin when I got to the SC 😅; it was 88 F outside. Got to SC with 12 rated miles left.

Moral of story: always use NOA on turnpikes so as not to miss the exit.


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## FRC (Aug 4, 2018)

NEVER drive past a supercharger unless you are CERTAIN of your ability to reach your next charging solution.


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## Kizzy (Jul 25, 2016)

TrevP said:


> The battery in the Model 3 is pretty much bullet proof. Don't overthink it, trust the trip computer estimate and charge when you can


That's a bold claim since we know the Model S battery pack is _definitely_ not bullet proof. 😉

I'd personally avoid the Supercharging stop (but mostly over cost). Over time, repeated Supercharging may start to reduce the max speed at which you can charge, but that's more of a far off issue for your use case.


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## Bigriver (Jan 26, 2018)

Regarding limits due to a lot of supercharging, both the model 3 and model X owners manual say the following:








I presume these same words are in the Model S and Model Y user manual.

Last Fall my 2017 model X had one of these restrictions placed on it, which limited the peak to 108 kW (at a V2 SC). It was a bit annoying (the car felt less shiny), but it is absolutely true that it increased a supercharger stop by only a few minutes. I only had the limit for a few months before an OTA update removed the limit. I do not know what cars did and did not get the SC peak rate restored, but I have only heard model X owners chiming in on the affirmative side.

As the limit was both placed and removed without a peep from Tesla, there is much I do not know. I have wondered if the restoration was due to the work of lawyers or engineers. I have hoped the latter, that upon further analyzing vast data or that improvements made to the BMS (such as preconditioning) that the limitation is not needed. Or perhaps there are just much higher limits now on what is considered a large number of fast DC charging sessions. No matter which, my brief experience with it was that the limit wasn't a big deal.


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## TrevP (Oct 20, 2015)

Kizzy said:


> That's a bold claim since we know the Model S battery pack is _definitely_ not bullet proof. 😉
> 
> I'd personally avoid the Supercharging stop (but mostly over cost). Over time, repeated Supercharging may start to reduce the max speed at which you can charge, but that's more of a far off issue for your use case.


I said the Model 3 battery, not the Model S battery.

Compare how many reports of battery fires and degradation on the Model S to the Model 3 and the relative VOLUME of each car and you'll see the Model 3 battery is far far more advanced than the previous design


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## FRC (Aug 4, 2018)

I supercharge my 2018 Model3 almost exclusively. At 82K miles, I have never seen a reduced peak charging rate notification.


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## garsh (Apr 4, 2016)

TrevP said:


> I said the Model 3 battery, not the Model S battery.











In Trevor's defense though, none of us really wants to click through to electrek.


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