Should the MYLR be charged to 50% only?

[Drinyth]

Of course, people are going to do what they want to do, but limiting yourself 100s' of miles of range a day in order to take a trip that might need to use that full range for a handful of days and save you some a couple hours to make up for 25 miles of extra degradation during that time, doesnt make sense, is all im thinking. What happens if you needed that extra range that day, superchargers all went down for an extended period (or the grid) or some other emergency circumstance? Best to have the range you have available to you than some very small degradation difference.

It would be better to just buy a shorter range vehicle and save the money by putting it into an investment or something. Then take the money out and buy a new battery once it wears lower than your comfort zone.

50% charge gives me around 150 miles or range. My typical drive is less than 10 miles. If you assume I need to get back home after that 10 miles, call it 20 miles between charges typically. I just don't see any reason to charge up to 90% when I'm typically back in 20 miles to charge back up again.

On a day when I know I'll need extra range, I'll charge my battery higher the night before.

On a day when I don't know that I'll need extra range, I'll go drive my ICE vehicle instead. I can't remember any time where I've suddenly at the drop of a dime needed to travel 100+ miles out of the blue. But I live in a metro area and my family is either here with me or far enough that I'd need to take a plane anyway.

But like I said, everyone's situation is different. If I didn't own an ICE vehicle an/or I had family that was 100+ miles away and I was an emergency contact for them or something, maybe I'd do something differently.

 

[Drinyth]

Tesla says it to charge to 90% so do that. Why complicate it?

I mean Tesla's official stance (from Home Charging - Frequently Asked Questions) is:

For regular use, we recommend keeping your car set within the 'Daily' range bracket, up to approximately 90%. Charging up to 100% is best saved for when you are preparing for a longer trip. You can adjust how full the battery charges from the charge settings menu.

"Up to approximately 90%" is different from "charge to 90%" Hence some people charging at the lower range of that daily range bracket trying to maximize battery longevity.

I think Elon said someplace that he charges his own vehicles to 90% on a daily basis. But if I had Elon type money, I wouldn't care about battery longevity knowing that I buy a new Model Y for 0.0000003% of my net worth.

 

[Spinkick]

I guess you guys think your batteries will wear out sooner than the bodies will? The question is, who thinks that charging differently means your batteries will then outlast the rest of the car?

 

[E90alex]

Of course, people are going to do what they want to do, but limiting yourself 100s' of miles of range a day in order to take a trip that might need to use that full range for a handful of days and save you some a couple hours to make up for 25 miles of extra degradation during that time, doesnt make sense, is all im thinking. What happens if you needed that extra range that day, superchargers all went down for an extended period (or the grid) or some other emergency circumstance? Best to have the range you have available to you than some very small degradation difference.

It would be better to just buy a shorter range vehicle and save the money by putting it into an investment or something. Then take the money out and buy a new battery once it wears lower than your comfort zone.

My commute is <30 miles round trip. I don’t need all that range on a daily basis. There will never be a scenario where I suddenly need to drive hundreds of miles out of town without notice. And even if so, superchargers exist in all directions from me.

Yes I realize keeping it around 50% is probably of small benefit vs 80% or 90%, but it is “better” and certainly isn’t harming anything besides reducing my range that I don’t need. Tesla’s 90% recommendation is a balance of range and battery health. They can’t recommend for people to try and keep it around 50% because that’s way more micromanaging than the general public will accept.

I’m not saying that everyone should do it because everyone’s situation and needs are different, but if it suits your use case then it could be something to consider. If I had a longer commute or I couldn’t charge at home then absolutely I’m not going to inconvenience myself for a small gain in battery longevity. But keeping it around 50% just happens to fit my use case perfectly, so why not.

 

[E90alex]

I guess you guys think your batteries will wear out sooner than the bodies will? The question is, who thinks that charging differently means your batteries will then outlast the rest of the car?

The batteries can absolutely wear out faster than the bodies. Plenty of older Model S are now experiencing significant battery degradation. Now Tesla has improved battery chemistry and design since then but no one knows yet how these batteries will be at the 8 year mark when the warranties age out. Maybe we’ll see 90% charges be 30% degraded by then and 50% charges only 15% degraded. Or maybe there will be zero difference.

Either way like I said, it’s not of any inconvenience or hinderance for how I personally use the car to try and keep it around 50% so why not? But if it doesn’t work for you then just charge it to however much you need it and don’t be afraid to use the car. I’m certainly not afraid to charge higher when I need it, but most of the time I simply don’t.

Even if I don’t own the car by the time 8 or 10+ years rolls around, I’d like to think I gave the battery a good start for its subsequent owners. And in the grand scheme of things, the longer the battery lasts the better it is for the environment, so there’s that.

 

[canbonbon]

Thanks everyone for very informative comments. I have learnt more about batteries than I did before. I think all our negativity towards LI batteries is due to cheap batteries used in Phones and laptops which have no thermal management.

My lifestyle also requires very less driving. I am actually not too sure why I bought the car but I did so its fine. So with little to no daily driving, I don't think I will need more than 150 miles range on any given day even for my city driving. And yes, there is almost 0% chance that I will drive more than 150 miles without prior notice and planning. This has never happened in my entire life and I really doubt it will ever happen based on the lifestyle we lead. So maybe I might just do the 50% charge and see how it goes.

Questions to those who charge only to 50%.
1) What is your lower limit? I mean when do you put your car back on the charger? when it drops to 40?30? etc. or it does not matter? You just do your errand and come back and put it back on charge (with 50% limit).
2) Do you keep your car connected all the time?
3) How do you set the limit? Is that in the app or in the car?

 

[Drinyth]

Thanks everyone for very informative comments. I have learnt more about batteries than I did before. I think all our negativity towards LI batteries is due to cheap batteries used in Phones and laptops which have no thermal management.

My lifestyle also requires very less driving. I am actually not too sure why I bought the car but I did so its fine. So with little to no daily driving, I don't think I will need more than 150 miles range on any given day even for my city driving. And yes, there is almost 0% chance that I will drive more than 150 miles without prior notice and planning. This has never happened in my entire life and I really doubt it will ever happen based on the lifestyle we lead. So maybe I might just do the 50% charge and see how it goes.

Questions to those who charge only to 50%.
1) What is your lower limit? I mean when do you put your car back on the charger? when it drops to 40?30? etc. or it does not matter? You just do your errand and come back and put it back on charge (with 50% limit).
2) Do you keep your car connected all the time?
3) How do you set the limit? Is that in the app or in the car?

1. Based on my driving, the lowest my car has gotten to was 37%. I follow the rule of ABC (always be charging). As soon as I get back in the garage (unless I know I'm heading out again very soon), I typically plug the car back in (with 50% limit). My charger is literally right next to where I park though so it's super easy.
2. Yes. If it's in the garage parked, it's typically connected. That also helps with warming up the car before leaving and pre-conditioning. That way, that energy spent towards climate/pre-conditioning uses energy while it's still connected to the wall charger.
3. You can set the limit either from the car or from the app. I find the app to be more precise as it's easier to use the slider to dial into an exact percentage (i.e. if I want it set at exactly 55%, for example).

 

[hsfrank]

The best thing to do is try not to overheat the battery or supercharge too much when its not. Supercharging does WAY more damage than charging on a level 2 over night ever would. Its best not to let this car put you in analysis peralysis. This car attracts us engineer types who want to analyze everything when in the end we should just be focusing our brains on something more useful

Why does Supercharging do more damage? Also since some of us get free supercharging is there a best ratio of supercharging to home charging.

 

[jcanoe]

Why does Supercharging do more damage? Also since some of us get free supercharging is there a best ratio of supercharging to home charging.

Lithium batteries undergo more stress when charged or discharged at a high rate. It is less stressful to keep the charging rate (in kilowatts, kW) to the battery capacity or less. With a battery with capacity (C) of 80 kilowatt-hours (kWh) this means charging at no more than 1 X C or 80kW. Urban Superchargers charge at up to 72kW, are theoretically less stressful to the battery. V2 Superchargers can charge at up to 150kW (about ~2C for the 80kWh battery) and V3 Superchargers max out at 250kW (this is ~ 3C.)

Tesla manages all aspects of the Supercharging session including temperature, voltage and amperage ramping. This minimizes any long term degradation of the battery. When a battery degrades it can no longer store and deliver as much energy (measured in kWh) as when the battery is new. In actual use it is the calendar aging of the battery that has the greatest impact on degradation, especially over the first 5 years.

The only downside to limiting charging to Supercharging would be convenience and cost. If I had access to free Supercharging I would seek out an Urban Supercharger if I was concerned about the long term impact of frequent Supercharging on the health of the battery but only if it was conveniently located. Home charging or charging when at work is usually the most convenient since your Tesla vehicle will be parked for hours. When charging at Level 1/Level 2 even the maximum Level 2 charging rate of 11.5kW is well below 1C and not stressful to the battery.

 

[Spinkick]

The batteries can absolutely wear out faster than the bodies. Plenty of older Model S are now experiencing significant battery degradation. Now Tesla has improved battery chemistry and design since then but no one knows yet how these batteries will be at the 8 year mark when the warranties age out. Maybe we’ll see 90% charges be 30% degraded by then and 50% charges only 15% degraded. Or maybe there will be zero difference.

Either way like I said, it’s not of any inconvenience or hinderance for how I personally use the car to try and keep it around 50% so why not? But if it doesn’t work for you then just charge it to however much you need it and don’t be afraid to use the car. I’m certainly not afraid to charge higher when I need it, but most of the time I simply don’t.

Even if I don’t own the car by the time 8 or 10+ years rolls around, I’d like to think I gave the battery a good start for its subsequent owners. And in the grand scheme of things, the longer the battery lasts the better it is for the environment, so there’s that.

Yes, anyone can choose to fill their gas tank 1/2 way every time they fuel up. You think the way you charge (within limits recommended, of course) is going to be what determines if your battery degrades quicker than the the rest of the car? That seems like poor engineering, to leave that up to the end user to micro manage. Those that have batteries go sooner had bad batteries. I designed them to last multiple hundreds of thousands of miles.

nobody is debating that you can/cant do with your car. We are simply having a thought experiment on what people are truly accomplishing.

 

[Spinkick]

Lithium batteries undergo more stress when charged or discharged at a high rate. It is less stressful to keep the charging rate (in kilowatts, kW) to the battery capacity or less. With a battery with capacity (C) of 80 kilowatt-hours (kWh) this means charging at no more than 1 X C or 80kW. Urban Superchargers charge at up to 72kW, are theoretically less stressful to the battery. V2 Superchargers can charge at up to 150kW (about ~2C for the 80kWh battery) and V3 Superchargers max out at 250kW (this is ~ 3C.)

Tesla manages all aspects of the Supercharging session including temperature, voltage and amperage ramping. This minimizes any long term degradation of the battery. When a battery degrades it can no longer store and deliver as much energy (measured in kWh) as when the battery is new. In actual use it is the calendar aging of the battery that has the greatest impact on degradation, especially over the first 5 years.

The only downside to limiting charging to Supercharging would be convenience and cost. If I had access to free Supercharging I would seek out an Urban Supercharger if I was concerned about the long term impact of frequent Supercharging on the health of the battery but only if it was conveniently located. Home charging or charging when at work is usually the most convenient since your Tesla vehicle will be parked for hours. When charging at Level 1/Level 2 even the maximum Level 2 charging rate of 11.5kW is well below 1C and not stressful to the battery.

Extremely well put. I think people are overestimating how much difference they are making because of their charging habits vs wear, when calendar aging is the real cause of degradation. There are rental companies charging these cars (supercharging even) multiple times a day for several hundred thousand miles, which have degradation in line with cars that are babied like the ones we are discussing in this thread.

People are going to do what they are going to do with their cars. You have guys with ICE vehicles changing oil every 3,000 miles with full synthetic, etc.

 

[E90alex]

Yes, anyone can choose to fill their gas tank 1/2 way every time they fuel up. You think the way you charge (within limits recommended, of course) is going to be what determines if your battery degrades quicker than the the rest of the car?

See that’s not equivalent because people don’t have a gas station at home so only filling up the gas tank half way is more of an inconvenience because you will have to go back more often.

That’s not an issue with an EV and home charging. I go home every day already so it’s zero extra work or inconvenience. And gas tanks don’t end up losing more capacity if you fill them all the way so there’s no reason to do a half tank other than if you didn’t have money for a full tank.

And absolutely the way you charge can affect battery degradation. That’s why Tesla doesn’t recommend 100% charge every day. They recommend up to 90% daily because that’s what they determined to be a good balance of acceptable battery degradation and end user range/convenience. If they had recommended for customers to try and keep it around 50% then that would be very inconvenient for a lot of people.

 

[Spinkick]

All im saying is tesla says things are fine up to 90 percent. Of course, charging above 90 will cause issues, they are not designed that way. Consider 90 percent charge as 100% with actually charging to "100%" being an overcharge situation and WILL make a difference. Holding less than that greatly less so, within the point that it doesn't even matter, which is what im trying to say.

Most manufacturers wont even give you that last 10%. They will program the car to stop at X voltage, whereas tesla allows you to overcharge for some extra range.

I stand that the battery will outlast the car (taking away calendar wearing and defective cells that you cant help). You arent going to cause defective cells by how you charge your car. They were defective anyway if they do fail.

Its okay to charge up less for reasons, but the main reason, to keep the battery fresh for longer, is negligable. The only way you will benefit from charging less is if you have the battery for a long time. The problem with that is that the older the battery gets, the more it degrades anyway So youll end up with lower capacity anyway due to time, no matter what you do charging wise (barring supercharging all the time and abusive charging, which I agree you should not do)

*Edits for spelling and grammar

 

[E90alex]

Questions to those who charge only to 50%.
1) What is your lower limit? I mean when do you put your car back on the charger? when it drops to 40?30? etc. or it does not matter? You just do your errand and come back and put it back on charge (with 50% limit).
2) Do you keep your car connected all the time?
3) How do you set the limit? Is that in the app or in the car?

1-2. I plug it anytime it’s in the garage. Lowest I’ve gotten is 19% after running around all over town on a Sunday.
3. I prefer the app because it displays the % you set it to as you drag the slider. The car does not show the % with the slider so it’s kind of a shot in the dark and hard to get the exact % you want. (Unless they added it in a recent update but I haven’t checked that)

 

[Drinyth]

Yes, anyone can choose to fill their gas tank 1/2 way every time they fuel up. You think the way you charge (within limits recommended, of course) is going to be what determines if your battery degrades quicker than the the rest of the car? That seems like poor engineering, to leave that up to the end user to micro manage. Those that have batteries go sooner had bad batteries. I designed them to last multiple hundreds of thousands of miles.

nobody is debating that you can/cant do with your car. We are simply having a thought experiment on what people are truly accomplishing.

Filling a gas tank in a ICE vehicle to 1/2 way has no beneficial effect that I can think of (other than maybe the slight weight savings that you get from having less mass in the vehicle) vs filling it to 100% . But frequently charging a battery to 50% vs charging it to 90%, based on what I've read, does have a positive benefit to the battery and keeps it from degrading as quickly. It's not an apples to apples comparison.

Now will charging to 50% determine if it makes the battery degrade less quickly than the rest of the car? Nobody can say that for sure. There are too many other variables to consider. But it is one thing that I can easily directly control and, for my use case, has zero downsides. But my use case isn't the same as other folks. If there were downsides to it from my own personal vantage point, then I'd reconsider my options.

 

[Apprunner]

Thanks everyone for very informative comments. I have learnt more about batteries than I did before. I think all our negativity towards LI batteries is due to cheap batteries used in Phones and laptops which have no thermal management.

My lifestyle also requires very less driving. I am actually not too sure why I bought the car but I did so its fine. So with little to no daily driving, I don't think I will need more than 150 miles range on any given day even for my city driving. And yes, there is almost 0% chance that I will drive more than 150 miles without prior notice and planning. This has never happened in my entire life and I really doubt it will ever happen based on the lifestyle we lead. So maybe I might just do the 50% charge and see how it goes.

Questions to those who charge only to 50%.
1) What is your lower limit? I mean when do you put your car back on the charger? when it drops to 40?30? etc. or it does not matter? You just do your errand and come back and put it back on charge (with 50% limit).
2) Do you keep your car connected all the time?
3) How do you set the limit? Is that in the app or in the car?

I charge nightly because of time-of-use plans where its cheapest. Going low won't hurt battery at all. You'd have to get very very low (under 0%) for a danger to the battery itself as there is a bottom buffer. Car starts to limit output on battery below 5% so I don't typically go below 10%. If you don't have time of use plan, then charge whenever or do it at a set schedule...probably doesn't matter at all.

Also, if you need it, don't hesitate to charge higher (like on weekends or trips). Also, heavy supercharging hasn't shown to degrade the battery much at all so don't be afraid to sue the Supercharger when you need to...these batteries are very robust. The number 1 rule is to keep it convenient for you

 

[Spinkick]

Filling a gas tank in a ICE vehicle to 1/2 way has no beneficial effect that I can think of (other than maybe the slight weight savings that you get from having less mass in the vehicle) vs filling it to 100% . But frequently charging a battery to 50% vs charging it to 90%, based on what I've read, does have a positive benefit to the battery and keeps it from degrading as quickly. It's not an apples to apples comparison.

Now will charging to 50% determine if it makes the battery degrade less quickly than the rest of the car? Nobody can say that for sure. There are too many other variables to consider. But it is one thing that I can easily directly control and, for my use case, has zero downsides. But my use case isn't the same as other folks. If there were downsides to it from my own personal vantage poi

Fair enough. The moral of the story is that yes, you can do what your want with your car. But dont worry about charging to 90 percent, other things will happen far sooner than the battery going, no matter what you do (within design limits)

 

[jcanoe]

Another thing I don't miss about not owning an ICE vehicle was keeping the fuel tank 3/4 or more full in winter. Keeping the fuel tank mostly full leaves less room in the fuel tank for moisture laden air. In cold weather this will reduce the chance of condensation and fuel contamination with water.

 

[bfayer62]

IMO there are more important things in life that making my batter last longer. I keep my MY charged at home to 80% for the same reason I fill the gas tank on my ICE vehicle when it gets to half way.

In an emergency or power outage, I know I have enough charge/gas to get where I need to go without charging or getting gas, either of which my not be available. Hurricanes, winter storms, family emergencies, or whatever else life throws at up.

 

[Apprunner]

Another thing I don't miss about not owning an ICE vehicle was keeping the fuel tank 3/4 or more full in winter. Keeping the fuel tank mostly full leaves less room in the fuel tank for moisture laden air. In cold weather this will reduce the chance of condensation and fuel contamination with water.

Kinda similar to EVs. In very cold temperatures, you can charge higher with minimal degradation. For example, 0 degrees at 60% is probably the same as 50 degrees at 50%. Of course you need to charge higher in the cold due to range hit.