Weekend Driver

[MrG_NY]

Question on charging and keeping the car plugged in or not.

I am getting ready to order and have a question about charging and the car sitting for periods at a time.The car will sit for most of the week since I work from home. The car will be driven when we go for dinner during the week usually one night. The car would be taken out some Friday evenings and use on the weekend for longer drives.The weekend milage cam be anywhere from 200- 400 miles plus.

The car will be parked outside in the driveway in the carport, I will be putting a charger in the carport. I may park the car outside the carport in the winter so my wife won't need to clean her car off if it snows.

Looking at a LR AWD

 

[jjrandorin]

Some form of this question is asked every 2-3 days on this site. Rather than say "search for it" like people do, and to (hopefully) head off the discussion that invariably follows, here is the guidance from tesla itself, in the manual for the car on page 122.

==========================================

About the Battery

Model 3 has one of the most sophisticated

battery systems in the world. The most

important way to preserve the Battery is to

LEAVE YOUR VEHICLE PLUGGED IN when

you are not using it. This is particularly

important if you are not planning to drive

Model 3 for several weeks. When plugged in,

Model 3 wakes up when needed to

automatically maintain a charge level that

maximizes the lifetime of the Battery.

Note: When left idle and unplugged, your

vehicle periodically uses energy from the

Battery for system tests and recharging the

12V battery when necessary.

There is no advantage to waiting until the

Battery’s level is low before charging. In fact,

the Battery performs best when charged

regularly.

Note: If the Model 3 Battery becomes

completely discharged in a situation in which

towing is required, the owner is responsible

for towing expenses. Discharge-related towing

expenses are not covered under the Roadside

Assistance policy.

The peak charging rate of the Battery may

decrease slightly after a large number of DC

Fast Charging sessions, such as those at

Superchargers. To ensure maximum driving

range and Battery safety, the Battery charge

rate is decreased when the Battery is too cold,

when the Battery’s charge is nearly full, and

when the Battery conditions change with

usage and age. These changes in the

condition of the Battery are driven by battery

physics and may increase the total

Supercharging duration by a few minutes over

time.

 

[gary3411]

I'm in about the same exact situation as you.

It is my guess that it truly doesn't matter if the car is plugged in or not as long as the battery is in a stable condition (40-90%). I think the whole "keep it plugged in whenever not driving" is simply a hedge to protect consumers against themselves from accidentally draining it too far. I do what's convenient and only plug in if it drops below 50 or I know I need a larger charge in the near future. I'm not an expert and this is not advice, but I do care deeply about the health of my car and logic tells me keeping it plugged in cannot be that important.

 

[MrG_NY]

Thank you for the response jjrandorin.
I have been reading the forum and read mixed reasons for plugging in or not. I figured to leave it plugged in and on the other hand knowing that Lithium ion batteries for tools should not be left in the charger I wanted to post the question. I had a friend have his house burn dow do to a battery overheating in a charger and starting the fire.

 

[Big Earl]

Thank you for the response jjrandorin.
I have been reading the forum and read mixed reasons for plugging in or not. I figured to leave it plugged in and on the other hand knowing that Lithium ion batteries for tools should not be left in the charger I wanted to post the question. I had a friend have his house burn dow do to a battery overheating in a charger and starting the fire.

It’s not good to leave lithium batteries at 100%. In a Tesla, you can set the change limit anywhere you want between 50% and 100%, so being plugged in doesn’t necessarily mean it’s going to charge to 100% like a cordless tool.

People spend countless hours on here discussing the pros and cons of various charge levels, when to charge, etc. There is plenty of existing reading material to keep you busy for at least several days.

 

[MrG_NY]

I'm in about the same exact situation as you.

It is my guess that it truly doesn't matter if the car is plugged in or not as long as the battery is in a stable condition (40-90%). I think the whole "keep it plugged in whenever not driving" is simply a hedge to protect consumers against themselves from accidentally draining it too far. I do what's convenient and only plug in if it drops below 50 or I know I need a larger charge in the near future. I'm not an expert and this is not advice, but I do care deeply about the health of my car and logic tells me keeping it plugged in cannot be that important.

Thanks for your reply Gary,
My thought is along yours. What if you had to take the car to the airport or cruise terminal, as long as you have a decent charge it should be able to sit for a week as long as everything is off.

 

[jjrandorin]

Thank you for the response jjrandorin.
I have been reading the forum and read mixed reasons for plugging in or not. I figured to leave it plugged in and on the other hand knowing that Lithium ion batteries for tools should not be left in the charger I wanted to post the question. I had a friend have his house burn dow do to a battery overheating in a charger and starting the fire.

If I were in your specific situation, based on tesla's guidance, I would have my car set to something like . 60% max charge level and keep it plugged in. If I knew I was going to drive a lot a specific weekend, I would bump it up the night before to 90% or whatever I thought I needed to cover the expected driving on the weekend I was going to do.

I would NOT "plug in every few days" or any such thing, I would just set it to 50/60/70% and plug it in every day and let the car do its thing.

 

[jjrandorin]

Thanks for your reply Gary,
My thought is along yours. What if you had to take the car to the airport or cruise terminal, as long as you have a decent charge it should be able to sit for a week as long as everything is off.

Depending on what you have on or off, the car is going to lose charge every single day. If you use features like sentry mode (which many people parking the car in a lot for storage would want to do), your car will lose 24-30 miles a day. If you dont use sentry or cabin overheat protection at all, you are looking at 2-6 miles a day of range loss.

 

[ewoodrick]

I plug in once or twice a week and over a year, no appreciable loss.
Tesla designed the car and battery so that you don't have to worry about it, so don't

Don't worry, the car will stay in the garage after the wife decides she wants to drive it during the week

 

[KenC]

My Model 3 is in a carport in Maine, and my UMC is right there. I set my SOC to 80%, and leave it connected all the time. Works fine.

Question on charging and keeping the car plugged in or not.

I am getting ready to order and have a question about charging and the car sitting for periods at a time.The car will sit for most of the week since I work from home. The car will be driven when we go for dinner during the week usually one night. The car would be taken out some Friday evenings and use on the weekend for longer drives.The weekend milage cam be anywhere from 200- 400 miles plus.

The car will be parked outside in the driveway in the carport, I will be putting a charger in the carport. I may park the car outside the carport in the winter so my wife won't need to clean her car off if it snows.

Looking at a LR AWD

 

[Nevada Jen]

For what it's worth, I don't think I would pay for the LR in your situation. LR seems a better fit for someone who drives their car more than one "tank" on a daily basis with no where to charge without losing time during the day.

 

[MrG_NY]

For what it's worth, I don't think I would pay for the LR in your situation. LR seems a better fit for someone who drives their car more than one "tank" on a daily basis with no where to charge without losing time during the day.

Going long range since I want all wheel drive and I will do 300 plus miles in a weekend. Drive a G80 now that has a 20 gallon tank. LR is a better fit.

 

[Watts_Up]

Going long range since I want all wheel drive and I will do 300 plus miles in a weekend.
Drive a G80 now that has a 20 gallon tank. LR is a better fit.

I agree, the SR is a good compromise as a second car especially if you can charge at home.
However you have to consider winter driving or just raining days, and the LR range is certainly more appropriate.

 

[darth_vad3r]

I'm not an expert and this is not advice, but I do care deeply about the health of my car and logic tells me keeping it plugged in cannot be that important.

Logic tells you that going against Tesla’s advice isn’t important?

Experts have said that more shallower depth of discharge is better for your battery than fewer deeper depth of discharges, so charging 2-3% every few days left plugged in (automatically each time it dips ”too far”) is not only healthier for your battery than less frequent longer chargers of say 10-20%, but also more convenient — since you’ll always be at your desired setpoint, even if the car went crazy overnight trying to download an update over weak wifi, or you left climate control or sentry on accidentally, or whatever.

 

[edigest]

It is my guess that it truly doesn't matter if the car is plugged in or not as long as the battery is in a stable condition (40-90%). I think the whole "keep it plugged in whenever not driving" is simply a hedge to protect consumers against themselves from accidentally draining it too far.

Another reason to leave it plugged in is to allow the battery management system to "level" the cells. A large disparity between cell levels (e.g., one cell fills to a lower level than others) can reduce the rated range.

Unfortunately, I can't find the reference but I read a study of the Tesla BMS that said it would continue to level the batteries if kept plugged after charging stopped.

 

[ewoodrick]

Logic tells you that going against Tesla’s advice isn’t important?

No, that's not my interpretation. Logic tells me that there is interpretation in Tesla's essentially one and only statement.

If we take it at face value, then everyone would be damaging their battery if it isn't plugged in all the time, except maybe when driving. Do you believe this? Should I leave the car at home plugged in and take Uber to work?

Okay, maybe that's an aggressive stance, but if you allow no deviance from the Tesla statement, then that is the stance that you are taking.

So we'll accept deviance. How long is okay to stay unplugged? 12 hours? 18 hours? 24 hours? 36 hours? If you are going to allow deviance, which number is the right number?

Or maybe we take it to the other extreme and say that you shouldn't leave the car unplugged for a year. Is that damaging? Doesn't the car completely shut everything down before the battery hits absolute 0 to keep from damaging the battery?

Or maybe we just get realistic about it and say that it's okay for the car to be unplugged or the car plugged in. You don't want to take it above about 80-90% on a regular basis. And you don't want to let it drop below 10-20% on a regular. (Let me caveat these statements with "It is okay to do this if you need to on a regular, basis. Tesla fully supports it".

There is a LOT of grey area here. And we'll assume that along with Tesla's essentially one and only written statement, that their organization wide (not up to individual interpretation) guidance is yet another version of "Tesla Guidance" As such, it doesn't seem to be a big deal since they don't continuously charge cars at Service or Delivery Centers. To the contrary, may people see the battery draining a lot when parked for a few weeks at Service Centers.


So why do we have to keep scaring all of the newbies into worrying so much about a car that was designed not to be worried about. I believe that Tesla doesn't give any battery specific guidance because they don't believe that it really is a big deal.
.

 

[darth_vad3r]

No, that's not my interpretation. Logic tells me that there is interpretation in Tesla's essentially one and only statement.

If we take it at face value, then everyone would be damaging their battery if it isn't plugged in all the time, except maybe when driving. Do you believe this? Should I leave the car at home plugged in and take Uber to work?

Okay, maybe that's an aggressive stance, but if you allow no deviance from the Tesla statement, then that is the stance that you are taking.

So we'll accept deviance. How long is okay to stay unplugged? 12 hours? 18 hours? 24 hours? 36 hours? If you are going to allow deviance, which number is the right number?

LOL take Uber to work. The best behaviour would be to strive to minimize the deviance as much as easily possible.

it doesn't seem to be a big deal since they don't continuously charge cars at Service or Delivery Centers. To the contrary, may people see the battery draining a lot when parked for a few weeks at Service Centers.

When I got my car I counted at least 5-dozen Tesla’s parked in the underground of the SC ... I don’t think they have that many plugs. Judging by the SC charge state seems irrelevant here

So why do we have to keep scaring all of the newbies into worrying so much about a car that was designed I believe that Tesla doesn't give any battery specific guidance because they don't believe that it really is a big deal.
.

??? ... but they DO give specific guidance ... they say to keep it plugged in! Ideal would be always plugged in when not driving. If it’s easy for you to do for it.

Don’t skip days on purpose to “help” the battery... it helps it to stay plugged in.

To re-quote the post we are talking about...

I think the whole "keep it plugged in whenever not driving" is simply a hedge to protect consumers against themselves from accidentally draining it too far. I do what's convenient and only plug in if it drops below 50 […] I do care deeply about the health of my car and logic tells me keeping it plugged in cannot be that important.

If one cares deeply, they should follow the advice as much as possible. More shallower discharge and recharge events are better than less deeper ones. There are lots of charts and research on this.

Tesla’s one-sentence advice is conveying all this advice in one sentence. And it's actually several sentences in the manual ...

Model 3 has one of the most sophisticated battery systems in the world. The most important way to preserve the Battery is to LEAVE YOUR VEHICLE PLUGGED IN when you are not using it. [bold, caps, emphais original, not mine] This is particularly important if you are not planning to drive Model 3 for several weeks. When plugged in, Model 3 wakes up when needed to automatically maintain a charge level that maximizes the lifetime of the Battery.

Note: When left idle and unplugged, your vehicle periodically uses energy from the Battery for system tests and recharging the 12V battery when necessary.

There is no advantage to waiting until the Battery’s level is low before charging. In fact, the Battery performs best when charged regularly.
​

So they say 3 things ... what's most important, that there's no advantage to waiting to get low to charge (actually there is a disadvantage is what they are implying), and that it performs BEST when charged regularly. Seems that if you care about your battery health you'd follow their advice:

1. The most important way to preserve the Battery is to LEAVE YOUR VEHICLE PLUGGED IN when you are not using it.
2. There is no advantage to waiting until the Battery’s level is low before charging.
   
3. the Battery performs best when charged regularly.