What is considered a "long trip" when considering charging to 100%?

[JulienWA]

I want to know what people and even Tesla categorizes as a "long trip."
I'm asking this because of all the back and forth about what you're supposed to charge your battery to..etc etc.
I do not have one of the new LFP packs, so I've been following the guidelines of only charging to around 80% as my daily behavior.

However, all advice says that you can charge to 100% only when you have a long trip. I'm wondering what that means? I regularly drive to another city that I live 2 hours from. I usually will charge to 100% and arrive in that city at around 56-48% depending on the weather. However, I'm thinking this trip is techincally not "long enough" to justify the 100% charge.

Is a "long trip" then something that would require a visit to a Supercharger before I would arrive at my final destination or do trips that ALMOST drain the battery (arrive at <20%) constitute a "long trip?"

 

[Tam]

..."long trip."...

I only charge 100% when 90% would not get me to my next charger safely.

If I safely arrive with plenty of charges like 48% then that is not a "long trip" to justify 100% charging.

 

[davewill]

I charge to 100% (at home) any time I think that a regular 80 or 90% charge might not be sufficient, or if the trip is long enough to require Supercharger stops. It's all subjective. Some people will feel that getting home below 50%, is a reason to worry, other not so much. Whether you do 100% charges 10 vs 20 vs 40 times a year is going to be pretty irrelevant as long as you aren't doing it every day (or more). That's not to say that if you have a long commute or travel frequently that 100% charging more often isn't an acceptable practice, after all what good is a car that you can't USE? However, if I had that situation, I'd be looking for ways to get a midday charge rather than doing 100%.

 

[GtiMart]

It just means "not regularly", not every day. You can charge to 100% from time to time, the important thing is not not leave it there for long.

The real question you have to ask yourself is : will I really gain any significant time by charging to 100% on that trip? If you have to stop anyway, charging to 100 instead of 90-95 will only get you a few miles farther before stopping, but you have to stop where there are superchargers anyway... Maybe that extra 5-10% won't even make a difference.

 

[3sr+buyer]

A reasonable definition of "long trip" would be one where you need to start at 100% to reach your destination or charging stop with enough remaining charge to be comfortable.

For example, with your trip that you go from 100% to 48% charge, if you are actually comfortable with arriving at 15% charge, then you can start at 67% or higher and be comfortable with it. However, if you then need to do additional driving at your destination before being able to recharge, or charging at your destination is expensive or inconvenient, you may need a higher minimum arrival charge to be comfortable about it.

 

[KenC]

I want to know what people and even Tesla categorizes as a "long trip."
I'm asking this because of all the back and forth about what you're supposed to charge your battery to..etc etc.
I do not have one of the new LFP packs, so I've been following the guidelines of only charging to around 80% as my daily behavior.

However, all advice says that you can charge to 100% only when you have a long trip. I'm wondering what that means? I regularly drive to another city that I live 2 hours from. I usually will charge to 100% and arrive in that city at around 56-48% depending on the weather. However, I'm thinking this trip is techincally not "long enough" to justify the 100% charge.

Is a "long trip" then something that would require a visit to a Supercharger before I would arrive at my final destination or do trips that ALMOST drain the battery (arrive at <20%) constitute a "long trip?"

A trip needing only about 50% is not a long trip, and running 100% to ~50% is worse for your battery than running 80% to ~30%. Or, if you think of a roundtrip, charging to 100%, still does not help you because you'll still need to top off to make it home comfortably.

Honestly, I set my SOC to 60% since my commute is just 30miles r/t. I don't top off before long trips, because it might only save me 5-10 mins at my first supercharger stop. Why go to all the hassle to change my charge limit the night before?

Trip simulations show that the fastest trip times are when you drive as fast as you are comfortable with, and charge at the lowest SOCs you are comfortable with. I set my target recharges for 15%, and destination SOC for 10%. That gives me the maximum range, with buffers I am comfortable with, and the fastest supercharger speeds. Anything else is going to cost you more trip time.

 

[threeputts]

I'll charge to 100% when leaving on any trip where my next charge will be a supercharger *if* I can time it so I leave right away when charging is complete. Just saves a bit of time and money at that first SC stop.

Whats a long trip? 500 miles or more IMHO.

 

[RayK]

I would call a trip where you need two or more Supercharging stops to be a "long trip". I'm planning to drive from San Jose, CA to Ashland, OR (~400 miles) next week. Using ABRP, I've charted out stops in Williams, Cottonwood and Yreka, with charger arrivals at 20% and max charges at 85%. One problem is that there's no Supercharger in Ashland. The closest Supercharger is in Medford, but in the wrong direction. So I plan to charge in Yreka to 80% and if I've figured it right, should have enough to get back to Yreka on the way home. But just in case, I can charge at one of the J1772 or CHAdeMO stations before leaving town. My wife initially chose a motel with a Tesla destination charger (unknown to her) but had to change properties as our arrival moved up a day earlier, so I had to be more concerned about my SoC when I get to Ashland.

 

[Brou]

Elon Musk said the recommendation not to charge to 100% is because the regenerative braking can't refill an already full battery, so the car is actually less efficient when fully charged.

But it seems there is some concern that charging to 100% is harmful to the battery. Has this been documented by Tesla? Is Elon just doing his foot-mouth-Twitter thing again? Or are both things true?

 

[house9]

One problem is that there's no Supercharger in Ashland.

There are some L2 chargers downtown and they are FREE!
4 hour max, but it is prime parking for downtown; most of them are next to Pony Expresso on Corner of Pioneer and Lithia Way.

- Lithia Way Parking Lot | PlugShare
- Transportation Electrification - Climate and Energy Programs - Find Resources - City of Ashland

 

[3sr+buyer]

Elon Musk said the recommendation not to charge to 100% is because the regenerative braking can't refill an already full battery, so the car is actually less efficient when fully charged.

But it seems there is some concern that charging to 100% is harmful to the battery. Has this been documented by Tesla? Is Elon just doing his foot-mouth-Twitter thing again? Or are both things true?

Yes, at 100%, regenerative braking cannot recover energy because there is no place to put it. However, that effect is no longer an issue after using a few percent of the energy. It may be more of an issue if you start on top of a hill, in which case, you want to start at less than 100% (perhaps enough less so that driving down the hill charges it up to 100%).

However, it is also the case that being at high levels of charge increases the capacity loss for lithium-ion batteries. This is true for both NCA and LFP chemistries, but LFP chemistry batteries (found in 2022 RWD and some late 2021 SR+ in the US) tend to have less and slower capacity loss than NCA chemistry batteries.

The Tesla recommendation to charge LFP chemistry batteries to 100% for daily use or at least once per week is due to the flat voltage curve that can allow the battery management system to lose track of the actual state of charge if the state of charge always stays in the flat part of the voltage curve (i.e. the part other than near 100% or 0%). So charging to 100% (where the voltage curve is not in the flat part) keeps the battery management system correct in knowing the actual state of charge.

 

[FirstInTown]

Search Battery University on the web. 100% is not best for sure and because Tesla doesn't protect a use a virtual buffer where 100% shown isn't REALLY 100% on the battery, Tesla 100% charge is not best for battery. Stay close to and cross 50% to be easiest on battery.

 

[jrweiss98020]

"Long trip" is one where you will need to charge away from home. Keep your 80% routine unless you need more; then charge to 100% at home. At the Supercharger, charge to 80% unless you NEED more.

 

[3sr+buyer]

Tesla doesn't protect a use a virtual buffer where 100% shown isn't REALLY 100% on the battery,

For the small number of models where there is a software limitation on the battery capacity, is it the lowest portion, highest portion, or middle portion of the capacity that is allowed to be used?

For example, the Model 3 SR has the SR+ battery with software limits. So, for the ~50kWh that is allowed to be used out of the ~55kWh battery, is it the 0-50kWh portion, 2.5-52.5kWh portion, or 5-55kWh portion that the software limits use to?

Obviously, this is not applicable to most Tesla vehicles.

 

[FirstInTown]

For the small number of models where there is a software limitation on the battery capacity, is it the lowest portion, highest portion, or middle portion of the capacity that is allowed to be used?

For example, the Model 3 SR has the SR+ battery with software limits. So, for the ~50kWh that is allowed to be used out of the ~55kWh battery, is it the 0-50kWh portion, 2.5-52.5kWh portion, or 5-55kWh portion that the software limits use to?

Obviously, this is not applicable to most Tesla vehicles.

Honestly don't know. Best would be it they used the middle. On my 2020 X, it's 100 KWh but 0 on screen is a 5kwh reserve at the bottom according to Scan My Tesla app. That might be usable, don't know, have never driven to 0% on screen. Lowest was 7%.

On my Chevy Volt, only get to use 14kwh out of 18.4kwh battery. I think it is a middle buffer.

 

[Kimmi]

How long is too long at 100%?

 

[AlanSubie4Life]

For the small number of models where there is a software limitation on the battery capacity, is it the lowest portion, highest portion, or middle portion of the capacity that is allowed to be used?

It’s the upper portion. These vehicles (SR) have a lot of regen at 100% SOC in spite of having NCA packs - this is how we know.

For capacity loss, everything just scales. There is no benefit on capacity loss to having a software-limited vehicle. If you are allowed to use 91.6% of your pack with an SR, and then your pack loses 5% capacity, you will lose 5% of that original energy of 91.6% of the original pack capacity. All just is proportionately scaled.

So 52.5kWh (SR+ pack pre-2021) means 48.1kWh for an SR.

So degrade by 5% and you will be able to use 45.7kWh of your 49.8kWh pack.

And the rated miles just scale down exactly as expected from the original 220 miles. The constant is 48.1kWh/220rmi, 219Wh/rmi.

 

[UncleCreepy]

I think this whole topic is overrated. I regularly charge my car to 95% at a public charging station and use it right after. When I arrive home, I'm typically at 90%. Why? Because I occasionally have to leave later and I don't want to sit there waiting for my car to charge at home and I don't want to pay for the electricity either if I can help it. Yes, I'm cheap.

Point is, after more than 70,000 km and more than 2.5 years since I got the car, my max rated range is still at 480 km (new: 504 km). It's been sitting there for more than a year. So it seems to be true that there is a little initial deterioration and then it stays relatively constant for a long time.

Long story short, if charging is cheaper at home than on the road and you want to go somewhere where you can't make it or can't make it back without charging on the way, just charge it to 100%. Just don't let it sit at 100% for days and you'll be fine. Imho this "keep the battery between 60-80%" wisdom is totally overrated.

 

[AlanSubie4Life]

my max rated range is still at 480 km (new: 504 km).

Presumably you mean 322mi/518km, assuming 18-inch wheels?

Seems like you are doing fine with 7.5% loss. (518->480) In any case perfectly normal and I agree that using slightly different charging habits won’t make an enormous difference (especially in Canada - this would be less true in hot climates though still it is not an enormous difference). Owning and charging the car should be easy and losing capacity is just part of ownership.

Not sure how to answer the original question here. I charge to 100% when I know it will shorten my overall trip time (even if it is only a very slight difference). So in the OP’s case I would not charge to 100% assuming destination charging was available.

 

[CKwik240]

For all the concerns about leaving it at 100% too long, charging on a scheduled departure is likely the best option here. For me "long trip" would be any trip that would beyond the 90% I keep mine at. I have yet to need this though.