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Charging Advice - ‘21 SR+

21EV

Member
Mar 11, 2021
28
5
Columbus, OH
I have a couple of quick questions. I just picked up a new March build SR+ this week and as of now don’t have L2 charging at home, as I‘m waiting on a couple of things first. Here is my list

  • I’ve seen talk of this car using the LFP battery from CATL, how do I confirm?
  • With that battery are there any differences in charging behavior, I’ve seen some stating to charge to 100%, others 80%, etc. Some have said Tesla recommended a 100% charge but I can’t find that advice anywhere.
  • The car is going to sit for up to a week soon, in my garage, and I only have a 120V outlet to plug in and it is unfortunately not a dedicated plug. Could I plug it in and set the amperage at something like 5 amps and would that even be worth it? Or would I better off just hitting a supercharger and topping it off before it sits?
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,237
9,094
Riverside Co. CA
I have a couple of quick questions. I just picked up a new March build SR+ this week and as of now don’t have L2 charging at home, as I‘m waiting on a couple of things first. Here is my list

  • I’ve seen talk of this car using the LFP battery from CATL, how do I confirm?
  • With that battery are there any differences in charging behavior, I’ve seen some stating to charge to 100%, others 80%, etc. Some have said Tesla recommended a 100% charge but I can’t find that advice anywhere.
  • The car is going to sit for up to a week soon, in my garage, and I only have a 120V outlet to plug in and it is unfortunately not a dedicated plug. Could I plug it in and set the amperage at something like 5 amps and would that even be worth it? Or would I better off just hitting a supercharger and topping it off before it sits?

That talk, I am fairly sure, is only relevant for European Model 3s and is not relevant (yet) for model 3s made in the US.


As far as sitting, since your garage plug isnt a dedicated one you likely shouldnt use it for an extended period of time when the car is sitting (and you may not be there).

A week time is not really a big deal. If you can start with 80-90% its not like you are going to come back to the car being fully drained after a week, provided you dont turn on sentry mode, make sure cabin overheat protections is off, and ensure you have not connected any 3rd party apps (or if you have, make SURE you have followed all directions to enable the car to sleep).

Only "check on" the car no more than once a day, as well, using the tesla app. If you follow those guidelines, you wont lose more than about 3-4 miles a day tops, which is 21 to 28 miles in a 7 day period. It should be fine as long as you dont leave with the car at 30% or something.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,127
7,133
Boise, ID
I’ve seen some stating to charge to 100%,
Don't.
others 80%, etc.
Sure.
Some have said Tesla recommended a 100% charge but I can’t find that advice anywhere.
No, I know what that's talking about and what you have heard related to that.

You are complicating this a lot more than it needs to be. On the charging screen in the car, you get to use the slider to choose the limit you want. It has two regions marked: "DAILY" (from 50% to 90%) and "TRIPS" (90% to 100%). Pick somewhere in the daily range and set it and forget it. Sometimes, if you do need extra range for a longer trip, then sure, go ahead and move that slider up into the "TRIPS" higher level.

The healthiest thing for the battery long term is not to spend a lot of time at the top or bottom end of the battery. So keep it somewhere in that middle area most of the time, but you know--high enough you do have enough practical driving range to use the car.

What you have heard about charging to full is just if the car's software estimate of its battery state is getting a bit out of touch. That number of "rated miles" can seem to drift down some over time, and giving the car a chance to measure the battery at the mostly empty and mostly full points can tune that in for a little more accuracy. But that's mainly just doing something for your peace of mind and the number you see, rather than actually doing anything helpful for the battery itself.
 

21EV

Member
Mar 11, 2021
28
5
Columbus, OH
Thanks for the help. I’m secretly plotting to replace our minivan with another EV so I want to get this right. On a related note the kids love riding in the car so that is helpful.
 

Zacster

Member
Sep 11, 2017
105
42
NYC
Thanks for the help. I’m secretly plotting to replace our minivan with another EV so I want to get this right. On a related note the kids love riding in the car so that is helpful.
We replaced our minivan with a model 3 and it does have some drawbacks. First thing that came up is we need a new storm door and that would just go in the back of the van. And the bikes too. We'll manage.

Find an outlet on a line that isn't shared, or at least not used elsewhere. I get 6mrph on a 116v line at 12a. I wouldn't leave it plugged in while you're away, not for the first time anyway. Don't worry about leaving it unplugged, it'll be fine. I've gotten used to just driving around and only plugging it in every 3rd day or so. I have an uninstalled wall charger now, so I'll get more in the habit of keeping it at 80-90% charge at all times once it is put in and I don't have to plug the mobile connector in.
 

21EV

Member
Mar 11, 2021
28
5
Columbus, OH
I did find one outlet that isn’t shared and is accessible thru the door from the garage into the house. It’s a NEMA 5-20 outlet but I only have the NEMA 5-15 plug that came with the car. I won’t leave the car plugged in like that while I’m gone for longer periods but temporarily until I get a more permanent setup I’m okay with it. I’m using rugs to cover the cord so the kids don’t trip over it.
 

jrweiss98020

Tessa's Tesla
Jan 9, 2020
423
297
Edmonds, WA
For the long layover, I'd charge the car to 90%, reset the max charge to 70-80%, and plug it in in your garage. It will not likely draw the full 12A for much, if any, of the time. What else is on the circuit? Lights & clocks don't draw much...
 

designrs

Member
Jun 24, 2020
204
204
Jacksonville, FL
Is there any evidence that 15A charging is detrimental to the car in any way?

I used to go out of my way to charge on level-2 when possible. Now I just plug it in to 15A circuit, which gives me 1kw / hr. My usual charges are about 5 hours. Sometimes 13 hours. It fits my lifestyle and I do have level-2 and supercharging nearby when needed.

For convenience now, I usually just plug it in to 15A and forget it.
Any problems?
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,237
9,094
Riverside Co. CA
Is there any evidence that 15A charging is detrimental to the car in any way?

I used to go out of my way to charge on level-2 when possible. Now I just plug it in to 15A circuit, which gives me 1kw / hr. My usual charges are about 5 hours. Sometimes 13 hours. It fits my lifestyle and I do have level-2 and supercharging nearby when needed.

For convenience now, I usually just plug it in to 15A and forget it.
Any problems?

Not detrimental, just more charging waste according to people here who study this stuff closely.
 

rjt!

Member
Sep 8, 2019
9
2
Atlanta, GA, USA
Not detrimental, just more charging waste according to people here who study this stuff closely.
There is a certain amount of power required to have the car ‘awake’, which is what it has to be to charge. Running the computers, running the battery heat or cooling if needed, and so on. That overhead is always there, it doesn’t depend on the rate of charge. So 1 amp, maybe 2 of overhead on a 15a/120v circuit is a ‘bigger loss of max charge rate’ than on (for example, what I have) an L2 40v//208v circuit. The drain is higher if the battery has to be heated or cooled while charging.

Think of it as parasitic loss that extends your charge time, and you have to pay for that parasitic loss since it is energy not used for charging over a longer period of time.
 

Zacster

Member
Sep 11, 2017
105
42
NYC
I'm getting a steady 6mrph on 117v/12a. I doubt the parasitic usage is 1amp though once the battery is warm. 6mrph is higher than I see anybody saying I should get.
 

21EV

Member
Mar 11, 2021
28
5
Columbus, OH
I’m not sure how to calculate miles of range per hour and that depends on how I drive as well! I did have the car sit for 7 days in the garage unplugged recently, with normal spring temperatures here in the Midwest. The car went from 79% state of charge down to 77%. I did use the app to check on it once or twice a day. That is pretty good and wouldn’t worry me for leaving it in airport long term parking for a similar duration.

I have charged it twice now using a 120V, 15A outlet and I seem to get enough charge for my usage though this being Covid my usage is down.

It does look like I’ll take my first trip where I’ll have to use a supercharger at the end of this month or beginning of next month. I assume I just need to have a valid credit card on file with my account but I’ll do some research before heading out.
 
Mar 23, 2021
14
8
Tarpon Springs, Florida
I’m not sure how to calculate miles of range per hour and that depends on how I drive as well! I did have the car sit for 7 days in the garage unplugged recently, with normal spring temperatures here in the Midwest. The car went from 79% state of charge down to 77%. I did use the app to check on it once or twice a day. That is pretty good and wouldn’t worry me for leaving it in airport long term parking for a similar duration.

I have charged it twice now using a 120V, 15A outlet and I seem to get enough charge for my usage though this being Covid my usage is down.

It does look like I’ll take my first trip where I’ll have to use a supercharger at the end of this month or beginning of next month. I assume I just need to have a valid credit card on file with my account but I’ll do some research before heading out.
It's my understanding you'll need a valid credit card on file or, if you scored any free supercharger miles, it will auto-deduct the miles from your account. I drove out of my way to test a supercharger earlier this week and just plugged it into my car and I was good to go. Got done, unplugged it, and just drove off. I did confirm my supercharger miles reduced accordingly. I charged about 40 miles in 10 minutes and was charged for 22 miles. For what it's worth..
 

Kianaf808

Member
Jul 1, 2020
22
2
Honolulu
Don't.

Sure.

No, I know what that's talking about and what you have heard related to that.

You are complicating this a lot more than it needs to be. On the charging screen in the car, you get to use the slider to choose the limit you want. It has two regions marked: "DAILY" (from 50% to 90%) and "TRIPS" (90% to 100%). Pick somewhere in the daily range and set it and forget it. Sometimes, if you do need extra range for a longer trip, then sure, go ahead and move that slider up into the "TRIPS" higher level.

The healthiest thing for the battery long term is not to spend a lot of time at the top or bottom end of the battery. So keep it somewhere in that middle area most of the time, but you know--high enough you do have enough practical driving range to use the car.

What you have heard about charging to full is just if the car's software estimate of its battery state is getting a bit out of touch. That number of "rated miles" can seem to drift down some over time, and giving the car a chance to measure the battery at the mostly empty and mostly full points can tune that in for a little more accuracy. But that's mainly just doing something for your peace of mind and the number you see, rather than actually doing anything helpful for the battery itself.
Good advice!!!
 

Adopado

Active Member
Aug 19, 2019
3,384
2,563
Scotland
Don't.

Sure.

No, I know what that's talking about and what you have heard related to that.

You are complicating this a lot more than it needs to be. On the charging screen in the car, you get to use the slider to choose the limit you want. It has two regions marked: "DAILY" (from 50% to 90%) and "TRIPS" (90% to 100%). Pick somewhere in the daily range and set it and forget it. Sometimes, if you do need extra range for a longer trip, then sure, go ahead and move that slider up into the "TRIPS" higher level.

The healthiest thing for the battery long term is not to spend a lot of time at the top or bottom end of the battery. So keep it somewhere in that middle area most of the time, but you know--high enough you do have enough practical driving range to use the car.

What you have heard about charging to full is just if the car's software estimate of its battery state is getting a bit out of touch. That number of "rated miles" can seem to drift down some over time, and giving the car a chance to measure the battery at the mostly empty and mostly full points can tune that in for a little more accuracy. But that's mainly just doing something for your peace of mind and the number you see, rather than actually doing anything helpful for the battery itself.
The LFP battery SR+ doesn’t even have the daily/trip distinction on the charging graphic. They can indeed be routinely used up to 100% if you need to. The advantage of lower limit charging still exists but is so small you may as well not worry.
 

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