What's the problem of charging your truck to 100% instead of 80% once in a while?

[Ward L]

I've charged my 2018 M3 over 500 times and have 243 cycles on the battery over 6+ years. New, it had 310 miles range. Tesla software bumped it to 321 miles. Now when I charge it to 100%, I get 303 miles, or less than a 6% loss. I've heard the batteries should last 1,500 cycles. I've calculated the battery should last about 375,000 miles. Of course, every battery is different, or are they? I have tried to vary the percentage I've charged it to between 70% and 90%. Gone to 100% maybe 5 times. I have no scientific evidence to support this claim, but I think (in my own little mind) it helps to vary the limit you charge to. Kinda like not creating a battery charge limit memory. Again, I doubt there is any science backing up this approach, but it makes me feel better! If it feels good, do it!

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[CTSoFL]

If you really want to get educated on the subject, there’s a thread over on TMC “Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health” but brace yourself, it’s 322 pages over 4 years lol.

The TL;DR is that cells age with cycles, but far more by just sitting there (“Calendar Aging”). The lower the SoC in storage, the lower the degradation.

From this chart you can see that capacity drops over time, and faster at higher SoC. Note there is a significant decline between 50% and 60%, so that’s where your greatest advantage is. It also gets steeper from around 80% to 100%.

It’s fine to top-up when you’re about to drive, but store it the lowest value practical (down to about 50%). That’s where I keep mine, as I don’t use more than around 15% per day typically.

There is also lower degradation with smaller Depth of Discharge (DoD) so you should charge daily rather than running all the way down and filling up.

Of course, you could charge to 100% all the time and still be unable to hit the 70% capacity limit in 8 years that would trigger a warranty replacement, but you might miss the 20%+ of range you lost.

Also, don’t be alarmed by range loss in the first year. The cells have a break-in period and degradation will slowly subside.

 

[FarAway]

Sure, but 50% is the minimum set point.

So, if I am NOT going to drive the truck for a couple of days, just leave it hooked up and set the charge to the minimum set limit of 50%?? and then top off to 80% just before my next trip?

 

[docowen]

We take trips skiing in the winter and typically leave in the afternoon after work on Friady. 150mi uphill in the cold (<32F). I have no charging option at work and limited charging options at the ski area. No Superchargers along the route.

Given only 150mi do I:
A. Charge to 80% like I normally do given that will more than likely be plenty of charge to get up there even in the cold. Probably depart at around 75% SOC when it is time to go.

B. Charge to 100% and leave it there for the 12 hours or so before we leave and depart with as much charge as possible.

 

[fhteagle]

Sure, but 50% is the minimum set point

Yes, but both the app and API let you stop charging below 50%. HomeAssistant + Teslemetry is how I accomplish this, and also scheduling charging + cabin preconditioning for the weird one off trips we have. Up until recently the Tesla app did not have a one time scheduled charge limit, so I built up my own system to schedule this as far out as I want instead.

 

[Celiboy]

We take trips skiing in the winter and typically leave in the afternoon after work on Friady. 150mi uphill in the cold (<32F). I have no charging option at work and limited charging options at the ski area. No Superchargers along the route.

Given only 150mi do I:
A. Charge to 80% like I normally do given that will more than likely be plenty of charge to get up there even in the cold. Probably depart at around 75% SOC when it is time to go.

B. Charge to 100% and leave it there for the 12 hours or so before we leave and depart with as much charge as possible.

I don’t know the answer to your question but also consider that while driving downhill 150 miles you’ll get the benefit of regenerative braking that will be adding some of those miles back.

While towing my boat to a lake that set at around 3200’ elevation I found I used less than half the kWh going down the mountain than going up over the approximately 22 miles from the lake to relatively flat land.

 

[docowen]

I don’t know the answer to your question but also consider that while driving downhill 150 miles you’ll get the benefit of regenerative braking that will be adding some of those miles back.

While towing my boat to a lake that set at around 3200’ elevation I found I used less than half the kWh going down the mountain than going up over the approximately 22 miles from the lake to relatively flat land.

Thanks for the info. I plan on not charging fully while up there to take advantage of the regen on the way down. I think 80% would be plenty to get up there but want to be sure. Also I have to consider if I leave and it is cold I will need to precondition so the battery is ready to take charge on regen given it is often in the single digits from a temp standpoint.

Which lake do you go to? I grew up just outside Yosemite in the foothills and frequented several of those lakes in the 90s

 

[Celiboy]

Thanks for the info. I plan on not charging fully while up there to take advantage of the regen on the way down. I think 80% would be plenty to get up there but want to be sure. Also I have to consider if I leave and it is cold I will need to precondition so the battery is ready to take charge on regen given it is often in the single digits from a temp standpoint.

Which lake do you go to? I grew up just outside Yosemite in the foothills and frequented several of those lakes in the 90s

You’re welcome. It was Bass Lake in Madera County. Great little lake and one of my favorites.

 

[TeslaKen]

I charge to 200% so I get 600+ miles of range...

 

[Woodrick]

If you really want to get educated on the subject, there’s a thread over on TMC “Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health” but brace yourself, it’s 322 pages over 4 years lol.

The TL;DR is that cells age with cycles, but far more by just sitting there (“Calendar Aging”). The lower the SoC in storage, the lower the degradation.

From this chart you can see that capacity drops over time, and faster at higher SoC. Note there is a significant decline between 50% and 60%, so that’s where your greatest advantage is. It also gets steeper from around 80% to 100%.

It’s fine to top-up when you’re about to drive, but store it the lowest value practical (down to about 50%). That’s where I keep mine, as I don’t use more than around 15% per day typically.

There is also lower degradation with smaller Depth of Discharge (DoD) so you should charge daily rather than running all the way down and filling up.

Of course, you could charge to 100% all the time and still be unable to hit the 70% capacity limit in 8 years that would trigger a warranty replacement, but you might miss the 20%+ of range you lost.

Also, don’t be alarmed by range loss in the first year. The cells have a break-in period and degradation will slowly subside.

I've looked at this graph many times and catch myself making the same mistake.

This graph does NOT show "over time" It only shows at 10 months.
And it shows that there's only 1% difference between 60 and 100%.

And since you can't set the max charge below 50%, it really says that the charge level doesn't matter.

 

[Woodrick]

You bring up a great point.

I get the "not 100% unless you really need it", but would daily charging to 85% be diffferent to battery pack longevity than 80%? 75%? Is 80% an arbitrary "we gotta pick some standard so y let's go with that" benchmark?

If you set it to 85%, you're going to get the nag message.

As others have mentioned, it used to be 90% max, but less than 2 years ago, Tesla dropped to 80%.

But charging to 100% periodically is not only allowed periodically, but it does help the batteries top off and the BMS to reset.

Take a trip quarterly and set it to 100% before you leave (and let it sit at 100% for hours) and life is good.

 

[Woodrick]

So, if I am NOT going to drive the truck for a couple of days, just leave it hooked up and set the charge to the minimum set limit of 50%?? and then top off to 80% just before my next trip?

If you aren't going to drive the truck for a couple of days, don't do anything.

The suggestion to drop is when the vehicle goes into longer term storage (i.e. weeks)

 

[Woodrick]

Thanks for the info. I plan on not charging fully while up there to take advantage of the regen on the way down. I think 80% would be plenty to get up there but want to be sure. Also I have to consider if I leave and it is cold I will need to precondition so the battery is ready to take charge on regen given it is often in the single digits from a temp standpoint.

Which lake do you go to? I grew up just outside Yosemite in the foothills and frequented several of those lakes in the 90s

If you are charging at the top, I wouldn't charge above 50%.

Cooler weather and higher SoC reduces regen.

Low regen going downhill means lest battery gain.

But most importantly it means more brakes!!!!

 

[CyberGus]

I've looked at this graph many times and catch myself making the same mistake.

This graph does NOT show "over time" It only shows at 10 months.
And it shows that there's only 1% difference between 60 and 100%.

And since you can't set the max charge below 50%, it really says that the charge level doesn't matter.

I consider 10 months to be a time period.

And it shows that there's only 1% difference between 60 and 100%.

I don't think you understand "percent".

it really says that the charge level doesn't matter.

It matters. Like, a lot.

 

[Woodrick]

I consider 10 months to be a time period.


I don't think you understand "percent".


It matters. Like, a lot.

Yes, it is a time period, but your statement of "over time" suggests a more continual process. For al this graph shows, it may have dropped to that number on day 2.

I absolutely understand percentage.
At 70%, the percentage loss was 5% (1-.95 on the graph)
At 80% it was 5 percent
At 90% it was 5.2%
At 100% it was 5.8% (or close)

Between a SoC of 60-100%, there's less than a 1% increase in loss.

The difference in degradation between keeping the battery at 60% and 100% over 10 months is SIGNIFICANTLY less than taking the wheel covers on a Model 3 off. Even the degradation is less than the wheel covers.

What is effectively says is that, in a Tesla, (which limits lowest max to 50%) the max setting is basically irrelevant at where you put it.

We know that Tesla has other recommendations. It just says that the batteries used in this study are not the same as the ones that Tesla uses.
Batteries are different. In some areas significantly different. Using case studies for other batteries is not an accurate representation of the batteries in a Tesla.

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