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

[CaseyL]

I have actually never charged to 100%
Usually 70-80% sometimes 90% extremely rarely to 95%

I've never charged to 100% either. Basically, I've just never needed to.
For daily commutes, I charge to 60%. I get home with 40%.

I usually charge to 80% at home to start a road trip. That stretches our first Supercharger stop just long enough to finish lunch before heading out again. Sometimes I'll charge to 90% at a Supercharger to get to a destination with about 55% left.

 

[AudreyHTX1]

It’s cheaper to charge at home. Other than that……

 

[Regaj]

Kinda the wrong question.

Battery health in an NCA-chemistry Tesla battery pack involves balancing a number of sometimes conflicting factors.

- Charging above ~3.92v/cell - a 60-65% SOC - induces cell stress. A 100% SOC is very hard on the pack, which is why Tesla recommends minimizing those occasions wherever possible.

- Elevated charge rates - Supercharging - induces cell stress, which is why Tesla recommends minimizing those.

- Large depth-of-discharge - inferred when one arrives somewhere with a very low SOC - induces permanent cell resistance in the pack. And, related, extended charge sessions - going from a very low SOC to a very high SOC - induce more cell stress than do multiple, shallower charge sessions.

So... do you charge to 100% so you can arrive back home without charging, but with a single-digit SOC? Or do you charge to 90%, with a single Supercharger stop to bring you from 25-65%, arriving home with 35%? Or do you charge to 80%, with two quick Supercharger top-offs?

The best advice I can give is to be mindful of what affects your battery, and to be as kind to your pack as reasonably possible... but not to let those things rule your life. Your car is for you to use, not the other way around.

 

[KenC]

- Charging above ~3.92v/cell - a 60-65% SOC - induces cell stress. A 100% SOC is very hard on the pack, which is why Tesla recommends minimizing those occasions wherever possible.

Why I chose 60% as my daily commute charge level at home, 3yrs ago. Wanted to see if avoiding potential cathode cracking would have any real world long-term benefits. Seems to be working, but I could just be lucky.

So... do you charge to 100% so you can arrive back home without charging, but with a single-digit SOC? Or do you charge to 90%, with a single Supercharger stop to bring you from 25-65%, arriving home with 35%? Or do you charge to 80%, with two quick Supercharger top-offs?

Going from 100% to single digit, just to avoid Supercharging, requires pre-trip preparation, and watching one's speed and/or climate settings. That may be something others don't mind, but if I can keep to my normal routine, I much prefer that. Plus, if you charge to 90%, then you probably only need a 5min stop somewhere. Hardly onerous, and I find if I'm making a stop anyway, why not just drive as fast as I'm comfortable with, and set my AC or heat to whatever I'm comfortable with. I find I save overall trip time by driving fast, and charging at low SOCs, over driving slower in order to meet some range goal.

I no longer do any extra pre-trip charging. I leave with 60%, just like for my daily commutes. At the first supercharger, I may have to charge another 5mins compared to if I'd left the house with 80%. I'd rather do that, than have to remember to set my charger to 80% the night before. Anyway, that's me, everyone else should do as Regaj says, do whatever is reasonable for you.

The best advice I can give is to be mindful of what affects your battery, and to be as kind to your pack as reasonably possible... but not to let those things rule your life. Your car is for you to use, not the other way around.

 

[DaveNN]

Noticed that my MY 2022 M3 ( 3k miles) only charged to 99% the other night.
All my home charges have been from well below 50% to 100% ( yes I ignored the warning)
Questions... Are these batteries so fragile that I've truly lost 1% since March?
How can I find out the type of battery fitted?

 

[AlanSubie4Life]

Noticed that my MY 2022 M3 ( 3k miles) only charged to 99% the other night.
All my home charges have been from well below 50% to 100% ( yes I ignored the warning)
Questions... Are these batteries so fragile that I've truly lost 1% since March?
How can I find out the type of battery fitted?

This just tells you the battery is not fully charged and tells you nothing about capacity loss. You can’t see that when in percentage mode.

Hopefully there is a good reason for you to charge to 100%. It’s really not the best idea, though if you have to, go for it.

 

[DaveNN]

This just tells you the battery is not fully charged and tells you nothing about capacity loss. You can’t see that when in percentage mode.

Hopefully there is a good reason for you to charge to 100%. It’s really not the best idea, though if you have to, go for it.

That's just it.
It was on charge overnight and would normally be at 100% by 8.30am latest.
I unlocked the charger and reapplied.

Nope...wouldn't play ball.

 

[AlanSubie4Life]

That's just it.
It was on charge overnight and would normally be at 100% by 8.30am latest.
I unlocked the charger and reapplied.

Nope...wouldn't play ball.

Normal. Not a big deal. Just tends to cut off near the 100% level. Very common.

If you want it to work and keep charging as much as possible, you can do tricks like turning on the AC, etc., which may tend to have the car not tell the UMC/Wall connector to de-energize, which may result in a tiny amount of flow to the battery (or not) and get it up to 100%. Waste of energy though.

For your battery capacity, you have to switch to distance display (tap battery icon at the top to toggle). No way to see it in percentage mode.

 

[Bouba]

That's just it.
It was on charge overnight and would normally be at 100% by 8.30am latest.
I unlocked the charger and reapplied.

Nope...wouldn't play ball.

I don’t think you can ‘top off’ the tank once it’s already in the high 90’s...it won’t go to 100% in those circumstances (at least mine didn’t)

 

[DaveNN]

Thank you chaps
I'm draining it down to 5% now and will see how it goes.
Yep, totally agree, 1% is not a lot but ...
It's a Co car, so why do I care?... I'm thinking a few years down the line and may buy it.

 

[DaveNN]

Normal. Not a big deal. Just tends to cut off near the 100% level. Very common.

If you want it to work and keep charging as much as possible, you can do tricks like turning on the AC, etc., which may tend to have the car not tell the UMC/Wall connector to de-energize, which may result in a tiny amount of flow to the battery (or not) and get it up to 100%. Waste of energy though.

For your battery capacity, you have to switch to distance display (tap battery icon at the top to toggle). No way to see it in percentage mode.

Yep... I tend to drive about in that mode...green and red go together.

 

[KenC]

It's like your home furnace thermostat swing. It may have gone to 100% during the night's charge, but by morning it had dropped to 99%, but the car doesn't top off immediately. It'll wait before topping back up.

 

[valem]

Thank you chaps
I'm draining it down to 5% now and will see how it goes.
Yep, totally agree, 1% is not a lot but ...
It's a Co car, so why do I care?... I'm thinking a few years down the line and may buy it.

Even if it's a Co car why not set the limit to 90% instead.
Do you really need all the range everyday?

Pros and cons of charging to 90% vs 100%:
Charging efficiency is significantly reduced when going to 100% as the charger works a lot longer to get it to 100%
Takes an unnecessary long time to get to 100%, therefore reducing charging efficiency. Same as above.
You don't have regen when you start driving, reducing your efficiency even further, and you have to use the brakes to stop.
So less charge efficiency, and less driving efficiency.
The ONLY benefit of charging to 100% is a little more range.

Unless you're getting home at the end of the day with a very low SOC, there is really no upside to charging to 100%

 

[valem]

I find I save overall trip time by driving fast, and charging at low SOCs, over driving slower in order to meet some range goal.

I have to disagree on that one, as making that one stop really really really lowers (like, big time) your overall trip, average speed.
If I could make it to my destination driving 55mph without a charge stop, vs driving 90mph with a charge stop, I guarantee you driving 55mph with no stop will get there first,

Now if you tell me it's more fun driving 90mph (with a charge stop) vs. driving 55mph and no stop, then there is no argument there.

That 0mph time will really kill your average speed... and from the moment you exit the highway, it's all 0mph (not just the charging stop) as you're not making any trip progress.

Also it would be nearly impossible to maintain 90mph if there is any amount of traffic...
I once did an efficiency test, as I wanted to see my % and rated mi drop difference driving 10 miles at 55, 10 at 60, 10 at 65, 10 at 70, 10 at 75 and 10 at 80, all in AP...
I was on a long boring trip, late evening, no wind, no hills (I-95 in FL) temp was low 70s so climate off... and my car, (a 2016 75D with 40k mi at the time) achieved 1 to 1 rated miles around 60-65, more than 1-1 rated miles <60 and less than 1-1 >65

Bottom line, I wasn't able to maintain a constant 80mph due to traffic interfering (75mph was the most that could be kept consistent over 10mi)
So generally anything above 75mph would not be easy to maintain as an average speed over a long trip except for rural areas.

 

[KenC]

I have to disagree on that one, as making that one stop really really really lowers (like, big time) your overall trip, average speed.
If I could make it to my destination driving 55mph without a charge stop, vs driving 90mph with a charge stop, I guarantee you driving 55mph with no stop will get there first,

Now if you tell me it's more fun driving 90mph (with a charge stop) vs. driving 55mph and no stop, then there is no argument there.

That 0mph time will really kill your average speed... and from the moment you exit the highway, it's all 0mph (not just the charging stop) as you're not making any trip progress.

Also it would be nearly impossible to maintain 90mph if there is any amount of traffic...
I once did an efficiency test, as I wanted to see my % and rated mi drop difference driving 10 miles at 55, 10 at 60, 10 at 65, 10 at 70, 10 at 75 and 10 at 80, all in AP...
I was on a long boring trip, late evening, no wind, no hills (I-95 in FL) temp was low 70s so climate off... and my car, (a 2016 75D with 40k mi at the time) achieved 1 to 1 rated miles around 60-65, more than 1-1 rated miles <60 and less than 1-1 >65

Bottom line, I wasn't able to maintain a constant 80mph due to traffic interfering (75mph was the most that could be kept consistent over 10mi)
So generally anything above 75mph would not be easy to maintain as an average speed over a long trip except for rural areas.

No need to debate, just go to ABRP where they use real-world data and run some simulations. It's conclusive. The fastest trip strategy is to go as fast as you are comfortable with and charge at the lowest SOCs you are comfortable with.

Here, I'll do the simulation since I use ABRP a lot. It's easy. Let's take Orlando to Tallahassee. It's 278 miles, and your strategy to go 55mph. Just looking at it, it should take about 5hrs, right?

As expected, around 5hrs. Starting at 100%, ending at 22%.

Now, let's go 113% of the posted speed limit. I don't know what the speed limit is, but if it's around 70mph, then 13% more is 79mph. I'm sure there'll probably be 1 stop.

And, yes, one stop, takes 6mins, charge from 13%, a low SOC, to 38%. Total trip time 3h49m, 34% more time if you go 55mph compared to going 13% over the posted speed limit. Doing the math, the avg driving speed was 75mph, which includes the off-highway driving as well.

So, even with a 6min stop, plus time to leave the highway, going 75+mph is significantly faster than driving 55mph with no stops.

 

[Resist]

I don't charge to 100% anymore because of how quickly it drops from 100% to 90%, I'm lucky if I get 30 minutes out on the highway.

 

[DaveNN]

It's like your home furnace thermostat swing. It may have gone to 100% during the night's charge, but by morning it had dropped to 99%, but the car doesn't top off immediately. It'll wait before topping back up.

You mean hysteresis.
That kind of makes sense
( my CH system uses opentherm)

 

[DaveNN]

Even if it's a Co car why not set the limit to 90% instead.
Do you really need all the range everyday?

Pros and cons of charging to 90% vs 100%:
Charging efficiency is significantly reduced when going to 100% as the charger works a lot longer to get it to 100%
Takes an unnecessary long time to get to 100%, therefore reducing charging efficiency. Same as above.
You don't have regen when you start driving, reducing your efficiency even further, and you have to use the brakes to stop.
So less charge efficiency, and less driving efficiency.
The ONLY benefit of charging to 100% is a little more range.

Unless you're getting home at the end of the day with a very low SOC, there is really no upside to charging to 100%

Very little to argue about there except for what's wrong with a bit more range?
I'd be lying if I said that I regularly do 300+ miles in a day.
However, having to find a supercharger when only 40miles from home is a bit frustrating.

 

[Undecided_2]

I’ve charged to 100% twice since picking the car up in March 2022. For a 500 mile journey I charge to 90-95%. We found that leaving with 100% the first 5% disappeared really fast, maybe 15mins into the journey. Then it ‘sipped’ at the battery. I suppose as there’s no regen?

However, I live in the U.K. and considering it’s small enough to fit into California with room to spare, making it to a SUC or off brand charger is no stretch.

 

[Undecided_2]

That's just it.
It was on charge overnight and would normally be at 100% by 8.30am latest.
I unlocked the charger and reapplied.

Nope...wouldn't play ball.

Mine does that occasionally. There is a thread that explains it somewhere. I have mine set to 60% SoC. It charges to 60% - I plug in after every trip - and sometimes it drops to 59-58% over 12+ hours. It will then charge up again to 60% if I don’t use it. I doubt they’ve set it to constantly keep the car at 60%.

Take it for a spin and then plug it in again. However, it’s not good practice to charge to 100% and have it sat there.