Optimal daily charging

What percentage

  • 50%

    Votes: 2 0.7%
  • 60%

    Votes: 4 1.3%
  • 70%

    Votes: 61 20.1%
  • 80%

    Votes: 128 42.2%
  • 90%

    Votes: 106 35.0%
  • 100%

    Votes: 2 0.7%

  • Total voters
    303

Dr Gez

Active Member
Joined
May 15, 2018
Messages
114
Location
Ottawa Ontario
Tesla Owner
Model 3
Country
Country
#1
I have about a 20 mile drive to work so based on my daily commute round trip I have no range issues. At home each night I charge up to 80% using the Tesla home charger. However at work I have access to a standard level 1 plug so could charge up for free my drive in - just want to ensure that doing smaller charges like that is fine for battery health vs doing one nightly charge.
 

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
11,072
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#2
Yep, perfectly fine.

So far, Tesla batteries have proven to be very robust. They show very little degradation, even after several years and hundreds of thousands of miles. So don't worry about things too much. Tesla has learned how to protect the batteries for the most part.

The general guideline for Lithium Ion batteries is:
  • Lithium Ion batteries don't like to stay at 100% full.
  • Lithium Ion batteries don't like to remain completely drained.
  • Lithium Ion batteries prefer to live their lives at about 50% charge.
Tesla already protects against these cases - you cannot actually drain the battery completely - the car will shutdown before that happens. And Tesla leaves a little margin at the top-end as well. So even if you did "charge up the whole way" every day, and "run it down close to empty" every day, there's still a little margin so that it's not too bad.

Now, if you want to "baby" the battery to help give it a long lifetime, try to keep it somewhere in the middle. Consider only charging to 80%, and never letting it get below 20%, for instance. If you're going on a long trip, don't be afraid to charge to 100%. Just don't leave the car sitting in the garage for a day or two at 100% charge - try to start driving it again within a few hours. Same thing with the low end - it's not terrible to run the battery down to almost empty, but try to charge it up again immediately - don't leave it parked when the battery is drained.

As for your specific question about charging from a regular outlet - slow charging is gentler on the battery, so not a problem at all. The only downside to 120v charging is that it's not as efficient as 240v charging. It's not that big of a deal though:
I wasn't able to find numbers for a Tesla, but I found several reports about the charging overheads for the Nissan Leaf.

Level 1 (120v, 12 amps): 78% efficient
Level 2 (240v, 16 amps): 91% efficient
Level 2 (208v, 30 amps): 91% efficient
CHAdeMO (500v DC, ~100 amps): 93% efficient

So it looks like there may be some minimum level of charge rate required to overcome the majority of overhead losses, then other factors become more important in calculating charging losses. Hopefully we can dig up similar reports for a Tesla.

Sources:
http://www.mynissanleaf.com/viewtopic.php?t=8583
https://avt.inl.gov/sites/default/files/pdf/fsev/SteadyStateLoadCharacterization2015Leaf.pdf
https://www.researchgate.net/profil...ency-of-quick-DC-vehicle-battery-charging.pdf
 
Last edited:

Brokedoc

Kick-Gas Contributor
Joined
May 28, 2017
Messages
1,715
Location
New York
Tesla Owner
Model X
Country
Country
#5
You have a very short commute. About 40 mi R/T. If you plug into a Level 1 and get about 5mi/hr, you should be able to replenish 40mi in about 8 hrs. I have a similar commute and typically charge to 70% daily in the summer (I have the 75kw in my X). In the winter with the heater and cold battery and less regen, I usually charge to 80%. If you know you will be doing errands or driving more the next day, you can bump up a little more charge the night before.

see my other thread. https://teslaownersonline.com/threads/tesla-charging-for-maximal-li-ion-battery-lifespan.4868/

This is a graph I pulled from EVTV about the Model S SOC/Voltage. As you can see, voltage drop is pretty linear except at the extremes where there are major chemical strains on the electrodes and in the lithium gel matrix. Generally keeping the SOC between 30 to 80% is best. Of course, the Tesla software likely has a built-in reserve so 20% displayed in the car is likely a true ballpark 30% SOC. Although the Model 3 has a slightly different electrode chemistry, the graph should be pretty similar to the S battery.

tesla48vdischargecurve_medium-jpg.10121
 

NJturtlePower

Living the Dream, Driving the Future!
TOO Supporting Member
Joined
Dec 19, 2017
Messages
1,167
Location
Flemington, NJ
Tesla Owner
Model 3
Country
Country
#6
I have about a 20 mile drive to work so based on my daily commute round trip I have no range issues. At home each night I charge up to 80% using the Tesla home charger. However at work I have access to a standard level 1 plug so could charge up for free my drive in - just want to ensure that doing smaller charges like that is fine for battery health vs doing one nightly charge.
Pretty thorough existing thread about battery care and charging recommendations here: https://teslaownersonline.com/threa...term-care-practices-for-tesla-batteries.6302/
 

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
11,072
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#8
Before passing judgment, the outlet is dedicated to my parking spot IMO.
I think it's perfectly acceptable for you to use an outlet if the company has given you permission. I don't think that MelindaV meant to pass judgment on you - she's just giving you something else to consider if there are others at work for whom the outlet could be more important.
 

Ed Woodrick

Top-Contributor
Joined
May 25, 2018
Messages
649
Location
Atlanta, GA
Tesla Owner
Model 3
Country
Country
#9
Before passing judgment, the outlet is dedicated to my parking spot IMO.
The wear and tear of plugging in daily, removing and packing the charger is going to make the effort significant in the advantages that you get out of it.

Don't worry about it, just enjoy the car.
 

Dr Gez

Active Member
Joined
May 15, 2018
Messages
114
Location
Ottawa Ontario
Tesla Owner
Model 3
Country
Country
#10
The wear and tear of plugging in daily, removing and packing the charger is going to make the effort significant in the advantages that you get out of it.

Don't worry about it, just enjoy the car.
I have been doing the daily plugin with my Volt for over a year and in the winter I will need to plug it in when our daily highs are like -20 celsius . When I picked it up in Toronto last week, the presentation they gave said the small charges were fine but then the person who showed me the car and walked me through the set up and put the batter charge to 80% max, told me to not charge at work as charging once a day was best for the car and not multiple charges.
 

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
11,072
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#11
... told me to not charge at work as charging once a day was best for the car and not multiple charges.
It's unclear which is better:
  • Fewer, deeper charge/discharge cycles
  • More, but shallower charge/discharge cycles.
I don't think it's worth worrying about too much with a Tesla.
 

tivoboy

Top-Contributor
Joined
Mar 24, 2017
Messages
592
Location
Palo Alto, CA
Country
Country
#12
Maybe slightly off topic here, but does anyone have a link that shows where the maximum charging rate kicks in and starts to throttle? I'd like to build a model for optimal charging rate at superchargers, assuming one is willing to stop more frequently but for shorter lengths of time each time. Personally, I'd rather do a road trip and stop every two hours for 10-15 minutes, than once every 3-4 hours for 30-40 minutes.
 

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
11,072
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#13
Personally, I'd rather do a road trip and stop every two hours for 10-15 minutes, than once every 3-4 hours for 30-40 minutes.
Well, the trick for fast supercharging is to charge *just* *enough* to arrive at the next supercharger with an almost-dead battery.

The problem with that approach is that you're kind of screwed if any one of your planned superchargers is out of order, or completely full when you arrive.
 

GregRF

Active Member
Joined
Sep 25, 2017
Messages
90
Location
Aptos CA
Country
Country
#14
Maybe slightly off topic here, but does anyone have a link that shows where the maximum charging rate kicks in and starts to throttle? I'd like to build a model for optimal charging rate at superchargers, assuming one is willing to stop more frequently but for shorter lengths of time each time. Personally, I'd rather do a road trip and stop every two hours for 10-15 minutes, than once every 3-4 hours for 30-40 minutes.
see here
 

NEO

Active Member
Joined
Jun 28, 2017
Messages
137
Location
Tucson, AZ
Tesla Owner
Model 3
Country
Country
#15
Well, the trick for fast supercharging is to charge *just* *enough* to arrive at the next supercharger with an almost-dead battery.

The problem with that approach is that you're kind of screwed if any one of your planned superchargers is out of order, or completely full when you arrive.
This, we just took a 1000 mile trip and on the last stop, the Tesla told us that we had enough charge to reach the our destination. Within 5 minutes the car was telling me I had to drive under 65 to reach the next destination, then 55. Finally I found a large truck going about 65 so I followed it and we got in with like 2 or 3 % left. The estimation ended up being off by 5% which is pretty significant. I will be overcharging by 10% on the trip home. That was just too close for my liking
 
Joined
May 2, 2018
Messages
9
Location
Oregon
Tesla Owner
Model 3
Country
Country
#16
Probably a good thread for my question. I only drive about 10-20 miles a day and charge every 3-4 days. Do some of the little batteries never get discharged unless you run it down to 10 miles or so, or does it matter?
 

Frank99

Model 3 owner since May 3, 2018
TOO Supporting Member
Joined
Aug 3, 2017
Messages
250
Location
Phoenix, AZ
Tesla Owner
Model 3
Country
Country
#17
RobPDX -
It doesn't matter. If you use up 10% of the battery charge, all the cells will lose precisely 10%. The Tesla battery management system assures that they're all balanced.
I would recommend only charging to 80 or 90% if you're only using 20 miles a day.
 

Dangermouse

Active Member
TOO Supporting Member
Joined
Apr 27, 2016
Messages
134
Location
Raleigh, NC
Tesla Owner
Model 3
Country
Country
#18
SOC question: we've had a few long trips where we make it home with ~10% charge remaining. Leaving the battery with a high SOC is not ideal...same for a low SOC? Should I immediately start charging when I get home to get it closer to its comfort zone, or would it be OK to wait (battery sits at 5-10% for half a day) and charge overnight like we normally do?
 

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
11,072
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#19
SOC question: we've had a few long trips where we make it home with ~10% charge remaining. Leaving the battery with a high SOC is not ideal...same for a low SOC? Should I immediately start charging when I get home to get it closer to its comfort zone, or would it be OK to wait (battery sits at 5-10% for half a day) and charge overnight like we normally do?
Caveat: keep in mind that all of this advice is just general advice for maintaining Lithium-ion batteries. We don't know for sure if Tesla's specific chemistry behaves the same, but we're reasonably certain that it does.

10% probably isn't too bad. At that point, I'd let the cost of electricity determine what to do:
  • If electricity costs a lot less at night, then just wait to charge it overnight.
  • If the cost doesn't change, then I'd start charging it immediately to get to 50%.
 

Dangermouse

Active Member
TOO Supporting Member
Joined
Apr 27, 2016
Messages
134
Location
Raleigh, NC
Tesla Owner
Model 3
Country
Country
#20
Caveat: keep in mind that all of this advice is just general advice for maintaining Lithium-ion batteries. We don't know for sure if Tesla's specific chemistry behaves the same, but we're reasonably certain that it does.

10% probably isn't too bad. At that point, I'd let the cost of electricity determine what to do:
  • If electricity costs a lot less at night, then just wait to charge it overnight.
  • If the cost doesn't change, then I'd start charging it immediately to get to 50%.
Thanks man. For a long time, I had been thinking (conceptually) that any charge was a strain on the battery, since it was holding more energy than an empty battery. That is a very different concept than the battery’s “state of rest” being in the middle at 50%, like equilibrium.