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RickW

Member
Aug 5, 2019
147
77
Seattle
Very quick question. If you are not going to drive your car for 2 weeks, keeping it parked in the garage, do you just charge to 90% and leave it unplugged, or do you leave it plugged in for the full 2 weeks and have it charge at night on schedule (ie using Stats to charge every 3-5 days while away)?
Additionally, if you leave Sentry Mode on then do you account for further degradation for the two weeks (I believe that it's 1 percent per day with everything off (and 3-5% with Sentry)). I could be wrong on these numbers but I've seen them posted.

Second question, what would you do if you have to be away for a month to prevent the battery dropping to 0?

Thanks.
 

St☰v☰

Member
Aug 27, 2019
787
530
SoCal/Texas
I think there is a "store" setting on the charge screen.

Nope, I was wrong, it's in a non-Tesla monitoring program:

Charging Modes.jpg


This isn't storing

potatos potatoes
 

go2realize

Member
May 23, 2019
52
39
Michigan
Very quick question. If you are not going to drive your car for 2 weeks, keeping it parked in the garage, do you just charge to 90% and leave it unplugged, or do you leave it plugged in for the full 2 weeks and have it charge at night on schedule (ie using Stats to charge every 3-5 days while away)?
Additionally, if you leave Sentry Mode on then do you account for further degradation for the two weeks (I believe that it's 1 percent per day with everything off (and 3-5% with Sentry)). I could be wrong on these numbers but I've seen them posted.

Second question, what would you do if you have to be away for a month to prevent the battery dropping to 0?

Thanks.
For a week of vacation, I charged the car to 80%, changed the limit to 50%, left the car plugged in and disabled all settings to reduce vampire drain and left. During the vacation, I checked the car only couple of times to avoid waking it up, thus also reducing the battery drain. I lost 1-2% per 24hrs over the week.
 

user212_nr

Active Member
Aug 26, 2019
1,407
744
US
For a week of vacation, I charged the car to 80%, changed the limit to 50%, left the car plugged in and disabled all settings to reduce vampire drain and left. During the vacation, I checked the car only couple of times to avoid waking it up, thus also reducing the battery drain. I lost 1-2% per 24hrs over the week.

Why the discharge? It is petty, but keeping the limit at 80 would avoid a 30% charge/discharge cycle on the battery.
 

go2realize

Member
May 23, 2019
52
39
Michigan
Why the discharge? It is petty, but keeping the limit at 80 would avoid a 30% charge/discharge cycle on the battery.
I don't know what caused the 1-2% discharge per 24hrs, but I assume it is normal for the TM3.

From what I read through this and other electric car forums, lithium-ion batteries are recommended to be at 30-50% capacity for long term storage. By keeping the limit to 50% and plugged-in, I ensured that it never falls too low. Since this was my first time leaving TM3 for more than couple of days, I charged it to 80% to understand the vampire drain also.
 

ivan801

Member
Oct 30, 2018
176
369
Lehi, UT
I think that we all agree that the best state of charge for storage is 50%. However, I believe that the marginal benefit is not worth even thinking about unless you are going to park it for months. When I go out of town I leave it plugged in and don't change my daily charge setting of 90%.

By the way, I also have two 2018 Nissan LEAFs that I charge to 100% every time I get a chance. Because they have a limited range of about 120-130 miles I just don't want to ever have to worry about it (or for my wife or daughter to worry about it). Yes, I know it's not ideal for LEAF batteries, but it's even less ideal for me to get a call from my daughter asking me how to use AAA.
 

SSedan

Active Member
Jul 24, 2017
2,948
2,323
Greenville Wisconsin
Why the discharge? It is petty, but keeping the limit at 80 would avoid a 30% charge/discharge cycle on the battery.

You are completely wrong, it would still discharge. 6% 5 times would still be a total 30% total discharge cycle. Topping up more often doesn't change total percentage.

There may be a tiny benefit to setting the charge limit to 50% as it is said the battery is happiest there, keeping it at 75-80% by topping up constantly is just keeping it at a needlessly high SOC. It is splitting hairs far as battery health at 50 vs. 80% though.
 
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rrolsbe

Member
Feb 18, 2017
232
129
Albuquerque
Follows is my understanding of this topic as it pertains to the Model 3 long range battery. Lets say the average phantom drain while on vacation is 2% or approx 6 miles/Day X 14 days that would be 84 miles. It is my understanding the charger will top off to the set charge level after an approx 3% drop or around 10 miles. So if the car is plugged into shore power, charged to 80% and the charge level is set 80% you would get 8 or 9 partial discharge/charge cycles while on vacation. If you charged to 80% and unplugged from shore power you would be at around 53% state of charge when you returned from vacation. When you charge the car back up to 80% in single charging session, you actually reduce the life of the battery slightly more than the 8 or 9 partial discharge/charge cycles. Of course, there are many other parameters involved like SOC, battery temperature, battery chemistry etc... For long term storage (two weeks is not really long term) I would charge the traction battery to 50% and keep the car in a temp range of no more than 25C/77F (lower the better) and no lower than around 0F (lower might be just fine? but certainly higher than -22f). Then put the car in storage mode as per the Tesla service document. After two months, the traction battery should still be close to 50% and would not have went though around 37 partial 3%/10 mile discharge/charge cycles. Since the 12V battery would be disconnected, attaching a Smart AGM battery charger to it might be a good idea. The AGM 12V battery will also not experience over 100 charge/discharge cycles during the two month period while is storage mode, thereby extending its usable life as well.
 

user212_nr

Active Member
Aug 26, 2019
1,407
744
US
Follows is my understanding of this topic as it pertains to the Model 3 long range battery. Lets say the average phantom drain while on vacation is 2% or approx 6 miles/Day X 14 days that would be 84 miles. It is my understanding the charger will top off to the set charge level after an approx 3% drop or around 10 miles. So if the car is plugged into shore power, charged to 80% and the charge level is set 80% you would get 8 or 9 partial discharge/charge cycles while on vacation. If you charged to 80% and unplugged from shore power you would be at around 53% state of charge when you returned from vacation. When you charge the car back up to 80% in single charging session, you actually reduce the life of the battery slightly more than the 8 or 9 partial discharge/charge cycles. Of course, there are many other parameters involved like SOC, battery temperature, battery chemistry etc... For long term storage (two weeks is not really long term) I would charge the traction battery to 50% and keep the car in a temp range of no more than 25C/77F (lower the better) and no lower than around 0F (lower might be just fine? but certainly higher than -22f). Then put the car in storage mode as per the Tesla service document. After two months, the traction battery should still be close to 50% and would not have went though around 37 partial 3%/10 mile discharge/charge cycles. Since the 12V battery would be disconnected, attaching a Smart AGM battery charger to it might be a good idea. The AGM 12V battery will also not experience over 100 charge/discharge cycles during the two month period while is storage mode, thereby extending its usable life as well.

Right, except that you will not get "8 or 9" partial cycles, but probably thousands of even smaller cycles. Leaving unpluggged (or plugged in with limit at -30% current SOC) just the same as leaving your car unplugged at night because you have enough to get to work and back the next day.

The effect is petty, but its not the optimal solution.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,432
7,633
Boise, ID
Right, except that you will not get "8 or 9" partial cycles, but probably thousands of even smaller cycles.
"smaller partial cycles" You're still quite getting the term. In battery industry studies, the charging event itself is not referred to as a "cycle". A "cycle" is defined as the full capacity of the battery depleted and refilled. This can be done in one piece, with dropping from 100% to 0% and then back up, or it can be done with:
half two times
a fourth four times
a tenth ten times
etc.
So if you are doing this thing with smaller amounts of running down and refilling, that is not "more cycles". It is just more of those events that it takes to add up to one cycle.

But that is why not all cycles are created equal. What are the temperature conditions? And if you are using half capacity X2, is that being done in the upper end: 50-100? Or is it more in the middle: 25-75? One type does cause a bit more stress than the other method.
 
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user212_nr

Active Member
Aug 26, 2019
1,407
744
US
"smaller partial cycles" You're still quite getting the term. In battery industry studies, the charging event itself is not referred to as a "cycle". A "cycle" is defined as the full capacity of the battery depleted and refilled. This can be done in one piece, with dropping from 100% to 0% and then back up, or it can be done with:
half two times
a fourth four times
a tenth ten times
etc.
So if you are doing this thing with smaller amounts of running down and refilling, that is not "more cycles". It is just more of those events that it takes to add up to one cycle.

But that is why not all cycles are created equal. What are the temperature conditions? And if you are using half capacity X2, is that being done in the upper end: 50-100? Or is it more in the middle: 25-75? One type does cause a bit more stress than the other method.

If the user always charges to 90% then you still have a cycle even though you did not reach 100%. 100% is not the actual capacity as we all know with some spare and being called "overcharged".

So if the user is charging to 90, then the battery drops to 89.9 and charges back to 90.0 then you have a cycle.

It is such a small "cycle" that it might not even deserve mention, but that is the point of leaving it plugged in.
 
  • Disagree
Reactions: SSedan and Rocky_H

Rocky_H

Well-Known Member
Feb 19, 2015
6,432
7,633
Boise, ID
If the user always charges to 90% then you still have a cycle even though you did not reach 100%. 100% is not the actual capacity as we all know with some spare and being called "overcharged".

So if the user is charging to 90, then the battery drops to 89.9 and charges back to 90.0 then you have a cycle.

It is such a small "cycle" that it might not even deserve mention, but that is the point of leaving it plugged in.
That is not how battery cycles are defined.
 

user212_nr

Active Member
Aug 26, 2019
1,407
744
US
That is not how battery cycles are defined.

Well using the industry definition makes it harder to talk about. I suppose one can refer to "depth of discharge" only. So in this user's case he has a 30% discharge vs thousands of minor discharges.
 

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