A couple of charging limit questions ... on my approach

A couple of charging limit questions ... on my approach

1. On long trips (I have taken 7 or 8 to SoCAL past year), I charge to 100% before starting out (sometimes the night before though, and then drive 13 miles home, so it sat overnight at near full charge). During the drive, after about 165 miles travel, I charge back up to around 305 - 310 miles at Kettleman before going on immediately, for another 150 miles. So, that *should* meet the recommended long-trip approach, right?

However, I also *occasionally* (once or twice a month) charge to near 100% at work on Friday afternoons (we get "free" charging at work - not supercharging) and then drive home for 13 miles - to about 290 miles left when I reach home. The intention is for the weekend to be without charging at all while we go around doing usual weekend stuff.

Is this a bad thing to do?

2. During the week, given the newer "90% is okay", and given that the range now should be "around 325 miles", I adjust the limit to middle of the right rectangle, to let the car charge to about 295 miles or so (i.e., *approximately* 90% of 325 miles). Is this too high? If I select the slider box to the beginning of the rectangle, it charges to about 280 miles before I drive home for the same 13 miles.

Is doing this bad?

BuffaloBillsFan | 21 juin 2019

I have no idea what the best strategy is. I re-charge my M3 to 90% at home if it gets below 50% (usually once or twice a week). I have taken several trips of >170 miles and fully charged at home before supercharging to 80% on the way home. I don’t know if this is the right thing to do, and I hope someone with more knowledge of the Tesla battery can help both you and me.

Syed.Hosain | 21 juin 2019

Yeah. It would be great to hear from people about their experiences.

TM3Q | 21 juin 2019

Now I only charge at 100% if I have to drive in winter when temperature is below -4F (-20C) for a long trip for safety. Anyway at that temperature even if I wanted to charge at 100% I reach 98% max

For the rest around 90-95% for long trips is good enough as I have supercharger not too distant between each of them

Frank99 | 22 juin 2019

1. For this scenario, charging to 100% actually slows down your trip. You have a 315 mile trip. You charge to 100%, drive 165 miles then charge back to nearly 100%, then drive 150 miles. That charging stop is going to be slow, because the charge rate slows down above 50% charge, and slows drastically as it approaches 100%. To make better time, leave with the battery below 75% range. You'll arrive at Kettleman with, say, 25% of range left - you'll be able to charge at maximum rate. Charge to perhaps 75% again, then continue your trip. Not only will this be faster, it's easier on the battery because you're never getting close to 100%. That said, I'll also say to not sweat the 100% cautions too much - your battery is likely to have 90% of its range still available when the car has 300,000 miles on it, so whether it has 90% or 92% isn't going to be a huge issue.

2. If you're only driving 26 miles a day, there's really no reason in the world to charge to 90%. In general, LiIon batteries are a LOT happier if you only charge to 95% rather than 100%, and are a bit happier if you only charge to 90% rather than 95%, and are a tiny bit happier if you only charge to 80% rather than 90%. I have similar circumstances to you, but I live in Phoenix (and the heat stresses the battery more, especially at high states of charge). I set my daily charge limit to 80% - once in a while, I'll drive 150 miles during a day which is still only 50% of the range of my LR RWD. I've never run into a need to charge during the day unless I'm on a long trip.

Don't be afraid of the battery range getting low - the car is VERY good about telling you the estimated range when you get to your next Supercharger/destination, and telling you to slow down if it doesn't look like you'll make it. I have no problem setting out on a leg of my trip with the car telling me I'll get there with 10% range remaining, and I've even set out with the car telling me I'll get there with 5% left - I just watch the estimate, and if it's going down I slow down.

jefjes | 22 juin 2019

What Frank99 said sounds like good advice to me.

ODWms | 23 juin 2019

Probably a wash on longer trips, where charging to 75-80% means you have to stop more times to go the same distance.

neilhamrin | 23 juin 2019

I rarely charge over 90% because of the reduced regen. But it likely is of little importance otherwise. My S after 72000 miles had almost no lose of range. And my now P3d- is doing well after 9000.

neilhamrin | 23 juin 2019

I rarely charge over 90% because of the reduced regen. But it likely is of little importance otherwise. My S after 72000 miles had almost no lose of range. And my now P3d- is doing well after 9000.

Frank99 lays it out very well IMHO

FISHEV | 23 juin 2019

"Is doing this bad?"

Tesla provides the basics on battery health, the 80-20 rule, charge to 80% and don't discharge beyond 20%. We have to assume this is optimal and li-ion battery tech pretty much states the same thing.

So anything outside of that will have a negative impact on battery life BUT life rules the car not the other way around and the impacts of going outside the lines are minimal.

For a long trip best strategy for me is least time spent charging vs. best for battery life and don't worry about incremental battery degradation.

Did you try the various trip planners to see what they said on charging strategy?

Neo101 | 23 juin 2019

Agree with the previous poster that charging becomes very slow as you reach higher SOC, so charge only as much as you need during stops on trips. Car does a good job of telling how much charge it needs to make it to the destination or next supercharger.

Secondly, i have heard that it's bad for the battery to sit at 100% charge. If you do need to charge to 100%, plan in a way that you can start driving soon after car reaches 100%. Also, no regen at 100%.

I personally charge only to 80% daily as that's all i need. No long trips yet :-(

Joshan | 23 juin 2019

I have 10k miles on my M3 I charge to 90% every night no matter what I used that day. It gets plugged in when done for the night. I have lost 0 miles yet...

I really think people WAY WAY overthink this.

FISHEV | 23 juin 2019

"I really think people WAY WAY overthink this."

You think?

End of the day its a car, it's got a job to do. Not changing the job for the car so we'll see how it does.

1. for battery as it has no impact on usage.
2. Long trips...whatever makes the trip least time.

Fredvanngo | 23 juin 2019

Second to @FISHEV. Do not over think ! Enjoy your Tesla. 80-90% approx.daily and 100% occasionally on trips are fine...if you have time to do it. :))

gballant4570 | 23 juin 2019

I charge to 90% daily, no matter how many miles were driven that day. Could be 250, could be 20. On Tuesdays I usually have a long driving day, so I add charge in the morning to get it close to or on 100%, and then drive the car. The longest I let the car sit at 100% was on an occasion that I forgot to move the charge limit back to 90%, so the next morning the car was sitting at 100%. However, my charging is timed to start at midnight, so the 100% charge might have been sitting for perhaps 3 hours.

After 9 months and 12+k miles, my car shows zero indication of battery degradation. It almost appears to show the opposite. Its a LR AWD config, and showed 306-308 miles at 100% consistently for quite some time. In the last couple of months its moved up a bit, and now shows 309-310 miles on a 100% charge. I am not believing that those estimated miles are an accurate indicator of the state of the battery, but I can see this as evidence that there has been no noticeable degradation.

I would essentially agree with Joshan - people have quite a tendency to overthink Tesla charging. There is a low end buffer in the battery intended to prevent complete discharge, and an upper buffer to protect battery health. It is very unlikely that the charging practices you've described will increase your future battery degradation, in my opinion.

jordanrichard | 23 juin 2019

While I was one of those that staunchly said to not go below 20%, I have changed my video that and for one simple reason, the trip planner. If running the car below 20% was a true concern, Tesla would not have the trip planner have you arriving at your next stop, with a SOC below 20.

JDev | 23 juin 2019

In answer to OP, yes doing this is bad, but can be OK with a couple small adjustments:
1) Charging to 100% SOC when needed occasionally is OK, but car should not be left above 90% SOC for unnecessary length of time - e.g. overnight. If you need 100% SOC, charge to 90% the night before, and top off to 100% shortly before departure which will use at least 10% SOC, so tome above 90% is minimized.
2) "adjust the limit to middle of the right rectangle", if I understand you, is 95% SOC not 90%. The right most rectangle under trip is range of 90%-100%, so 90% is the left side of the rightmost rectangle. Don't charge above 90% unless needed for a trip (which is why that range is marked trip vs daily). 90% should be under the T in TRIP.

JDev | 23 juin 2019


Syed.Hosain | 24 juin 2019

Thanks for all the feedback and comments, folks!

Syed.Hosain | 24 juin 2019

@Frank99 ... thanks for the very specific advice. I will try it on my next trip down south.