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Is leaving Tesla plugged in while not charging really beneficial?

CyberGus

Not Just a Member
May 5, 2020
1,444
3,336
Austin, TX
I'm actually less concerned about the slow reduction in range, and more worried about total pack failure (expensive fix!). However, pack failure seems to be caused by the total failure of one or more cells, and I don't know that there's any correlation between charge behavior and cell death. It seems to be a crapshoot. 🤷‍♂️
 
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I'm actually less concerned about the slow reduction in range, and more worried about total pack failure (expensive fix!). However, pack failure seems to be caused by the total failure of one or more cells, and I don't know that there's any correlation between charge behavior and cell death. It seems to be a crapshoot. 🤷‍♂️

True. I've seen very little written about pack failures. However, there seems to be an infinite amount of info, thoughts, opinions, and misinformation about battery degradation.

I wonder if an excessive number of charges to 100% or discharges below 10% can eventually cause a cell to fail? Or are some cells doomed to fail no matter what?
 
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ucmndd

Well-Known Member
Mar 10, 2016
8,827
17,133
California
I just don't understand why people insist on doing something other than the recommendation by the manufacturer. 🤷‍♂️
Feelings, man. And bad info / old habits.

the owners manual said:
There is no advantage to waiting until the Battery’s level is low before charging. In fact, the Battery performs best when charged regularly.
 
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I use Departure Charging (off-peak). Set to depart at 8am. With my Tesla HPWC, It will start to charge around 630am.

Even though I plug in the day before, it doesnt do anything at all until its charging time. So I question what does having it plugged in benefit? I can technically go and plug in at 630am myself manually. Is there or could there be situations where some power draw would happen during the night for battery/thermal needs?
 

jcanoe

Well-Known Member
Oct 2, 2020
5,737
6,358
Maryland
I use Departure Charging (off-peak). Set to depart at 8am. With my Tesla HPWC, It will start to charge around 630am.

Even though I plug in the day before, it doesnt do anything at all until its charging time. So I question what does having it plugged in benefit? I can technically go and plug in at 630am myself manually. Is there or could there be situations where some power draw would happen during the night for battery/thermal needs?
If you plug in each evening with Scheduled Departure charging enabled the Tesla Model Y does not draw power from the grid until charging begins. If it is cold enough the Tesla Model Y will have to warm the battery prior to charging. The Tesla Model Y will draw power from the grid when warming the battery for charging. The Tesla Model Y does not warm the battery when the Model Y is parked, only as part of a charging session or while preconditioning before driving.
 
If you plug in each evening with Scheduled Departure charging enabled the Tesla Model Y does not draw power from the grid until charging begins. If it is cold enough the Tesla Model Y will have to warm the battery prior to charging. The Tesla Model Y will draw power from the grid when warming the battery for charging. The Tesla Model Y does not warm the battery when the Model Y is parked, only as part of a charging session or while preconditioning before driving.
So is it better to not have it on scheduled departure and try to have it charged ASAP so it can also draw power from grid? I live in Las Vegas so high temperatures. I do have a garage. I keep the Model Y at 50% charge limit and my wife depletes it to 35% worst case.

It will charge to 50% in about an hour and then just sit there all night? Will any power be used to thermally condition battery in hot temperatures that I am missing out on with scheduled departure?
 
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So is it better to not have it on scheduled departure and try to have it charged ASAP so it can also draw power from grid? I live in Las Vegas so high temperatures. I do have a garage. I keep the Model Y at 50% charge limit and my wife depletes it to 35% worst case.
Departure schedule benefits the most when the battery pack is cold. If the battery is already at optimal temperature then no pre-heat is needed. If the temperature is really high (more than 95F ?) then it may use AC to cool it down before departure.

It will charge to 50% in about an hour and then just sit there all night? Will any power be used to thermally condition battery in hot temperatures that I am missing out on with scheduled departure?
The car doesn't condition the battery unless it's getting ready for departure. So yes, it will charge to 50% in your case and just sit there.
If you schedule departure then it conditions the cabin and the battery using grid power (when plugged in) if needed.
 
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jcanoe

Well-Known Member
Oct 2, 2020
5,737
6,358
Maryland
So is it better to not have it on scheduled departure and try to have it charged ASAP so it can also draw power from grid? I live in Las Vegas so high temperatures. I do have a garage. I keep the Model Y at 50% charge limit and my wife depletes it to 35% worst case.

It will charge to 50% in about an hour and then just sit there all night? Will any power be used to thermally condition battery in hot temperatures that I am missing out on with scheduled departure?
Scheduled Departure charging so that charging takes place in the early hours of the A.M. is more grid friendly than immediately charging upon plugging in.

The only time that the Tesla vehicle will warm the battery above ~40F is when navigating to a Supercharger. Then the Tesla vehicle will warm the battery up to ~115F for optimal Supercharging.

Inside a hot garage where the daytime temperature inside the garage can climb well above 100F the Tesla vehicle may circulate coolant, using the radiator to help cool the battery. It is not clear, at least to me, if the AC compressor is used to help cool the battery when the Tesla vehicle is parked. This does happen right after the Tesla vehicle has been driven and the battery is warm.) If the AC comes on while parked you might find condensate beneath the vehicle but in dry desert climate this water could evaporate before you notice. The Tesla vehicle does not have to be plugged in to cool the battery.
 
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Inside a hot garage where the daytime temperature inside the garage can climb well above 100F the Tesla vehicle may circulate coolant, using the radiator to help cool the battery. It is not clear, at least to me, if the AC compressor is used to help cool the battery when the Tesla vehicle is parked. This does happen right after the Tesla vehicle has been driven and the battery is warm.) If the AC comes on while parked you might find condensate beneath the vehicle but in dry desert climate this water could evaporate before you notice. The Tesla vehicle does not have to be plugged in to cool the battery.
So whether plugged in (instant), plugged in (scheduled) or unplugged, the vehicle will behave the same from a battery thermal management standpoint in my garage? No difference?
 

jcanoe

Well-Known Member
Oct 2, 2020
5,737
6,358
Maryland
So whether plugged in (instant), plugged in (scheduled) or unplugged, the vehicle will behave the same from a battery thermal management standpoint in my garage? No difference?
Yes, the Tesla vehicle behaves the same when parked whether plugged in or unplugged. When Tesla vehicle remains parked for a period of time the battery state of charge will start to drop. This happens more quickly if Sentry mode is turned on at the parked location. After the battery charge level drops a few percent, if plugged in the Tesla vehicle will charge the battery up to the preset charge limit.
 
Your feelings on the subject aside, your chosen charging habits (fewer, deeper, discharge cycles) are objectively worse than more frequent smaller cycles.

You should stop if your primary objective is to maximize battery health.
Are there other measurable metrics besides range degradation that, as owners, we can check to confirm battery health? I've had my Y LR for a week shy of a year and driven 15K miles so far. I charged it to 100% this past weekend, for the 3rd time ever, prior to a 200 mi trip. My range degradation over the first year is 5 miles (321 miles at 100%), or about 1.5%. My efficiency is 252 wh/mi lifetime and that number is still slowly decreasing, i.e. becoming more efficient. I just want to know if there is a metric I can check to see if my charging habit is causing damage to the battery in some other way.
 
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Good question.
@Benito1283, I should have clarified that I have no reason to doubt the car will use AC to precondition the battery or set climate prior to departure. I don’t use these features, as I live in a temperate climate. I am skeptical that my car is using AC overnight when it is not charging.

The downsides to plugging in overnight are minor. A power surge is probably the biggest reason, but the wear and tear on the charging port and just the general hassle for a presumed useless activity are also factors. But I’m willing to do it if I can discover a good reason.
I get the whole point of your question. If you don't need to charge, yet you CAN plug in, SHOULD you plug in? If battery has say 50% charge or more, left only overnight, is there ANY point to plugging in? I have wondered the same. There is hassle to constantly plugging/unplugging and wear and tear on the charge port. So it is a good question.
In some cities, you see many Teslas parked on the street for hours or overnight with no way to plug in. I have neighbors who leave theirs on the street unplugged for days, but they could put in the garage and plug in. Are they harming the long term life of their batteries? It would seem unlikely.
 
Good question.

I get the whole point of your question. If you don't need to charge, yet you CAN plug in, SHOULD you plug in? If battery has say 50% charge or more, left only overnight, is there ANY point to plugging in? I have wondered the same. There is hassle to constantly plugging/unplugging and wear and tear on the charge port. So it is a good question.
In some cities, you see many Teslas parked on the street for hours or overnight with no way to plug in. I have neighbors who leave theirs on the street unplugged for days, but they could put in the garage and plug in. Are they harming the long term life of their batteries? It would seem unlikely.
You're harming the long term health of your batteries if you're charging above 50% when you don't need to. My vehicle is pretty much always below 50% (the charge limit is set to 50%) except when I am doing longer trips, and when I do that, it charges up just before I leave so the amount of time spent over 50% is minimized. I always plug in when I park in the garage.
 
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You're harming the long term health of your batteries if you're charging above 50% when you don't need to. My vehicle is pretty much always below 50% (the charge limit is set to 50%) except when I am doing longer trips, and when I do that, it charges up just before I leave so the amount of time spent over 50% is minimized. I always plug in when I park in the garage.
This is another topic entirely. I never charge to over 50% unless doing a trip the next day. You can't set less than 50% as the setpoint anyway. I find it odd Tesla wouldn't give a warning if it harms long term health of the batteries to exceed 50%.
The original question in the thread, is it helpful to plug in at all times ? Why do you always plug in when you park in the garage? Does this extend the battery life? There seem to be some differing opinions on this.
 

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