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Sheltering in Place - Charge or not

hmgolds

Member
Aug 30, 2018
128
95
Brainerd, MN and Boston, MA US
I haven't left my home in 9 days. I just have it plugged in and the charge limit set down to 50%. 50% is still plenty of miles if I need to venture out for food or supplies. I have a HPWC so if I do need to hit the road for whatever reason, I can up the charge limit and top it off pretty quickly.

I can't argue with that for you. But the OP charges on house current (I take that to mean 15a, 120v). And what would concern me (especially for a 75yo in California) is the possible need to drive 100 or even 200 miles to get to a hospital accepting patients. Since there is no material downside to charging to 80%, that's what I would do in his situation.
 
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erb2000

Member
Jan 3, 2020
15
39
Bedford, MA
I can't argue with that for you. But the OP charges on house current (I take that to mean 15a, 120v). And what would concern me (especially for a 75yo in California) is the possible need to drive 100 or even 200 miles to get to a hospital accepting patients. Since there is no material downside to charging to 80%, that's what I would do in his situation.

This is incorrect. See https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
tl;dr: Only charge to 50%.
 

Vancan

Member
Nov 5, 2018
22
13
Vancouver
drive your tesla around. You don’t gotta get out the car..
Yup that's what I do: carry Lysol wipes, disinfect all the door handles and elevator buttons you touch going to and from your car, and don't get out of it during your drive. In my case I live alone and am the only driver, so no chance of picking up or passing on anything. And the option to get out and drive is so liberating during this self-isolation time!
 
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Nopantz

Member
Feb 28, 2019
51
50
Denver Metro
I was charging often 50-80% and my battery was reporting low (~290 mi after about 10K miles). Despite what the manual said, the service center recommend charging 30%-70$ or 20%-80% for better calibration. They had me deep cycle the battery - I ran it down to 7mi and then charged it to 100% to recalibrate it, now maybe I'm 297-299 mi on M3D.
 

hmgolds

Member
Aug 30, 2018
128
95
Brainerd, MN and Boston, MA US

Note that I said "material" downside. Show of hands, how many of us only charge to 80%? How many of us would have bought a Tesla if you could only charge to 50% on a regular basis? Further, we don't necessarily know how Tesla's battery management comes into play. While putting a Tesla logo on a battery doesn't change the laws of physics or chemistry, we do know that there are controls in place to prolong life. So 80% as measured and reported by the charging circuit may not be the 4.05v per cell as tested in the article you referenced.

In fact, the article you referenced states "Industrial devices, such as the EV, typically limit the charge to 85% and discharge to 25%, or 60 percent energy usability, to prolong battery life.". Does that mean 100% as reported by the charging app is really 85% of battery voltage? I don't know.

So I don't disagree with your comment that charging to an actual cell level of 50% might be best, I just question whether doing so in our Teslas - as reported by the Tesla charging system - leads to the same benefit. And whether that benefit is significant enough to worry about.
 

smatthew

Active Member
Jun 9, 2018
1,292
2,233
CA Bay Area
If you only charge to 80% your batteries will become imbalanced over time. The only way to fix this is to leave the car above 85% SOC for days. People who have only been charging to 80% have seen reported capacity drop.
 

erb2000

Member
Jan 3, 2020
15
39
Bedford, MA
Note that I said "material" downside. Show of hands, how many of us only charge to 80%? How many of us would have bought a Tesla if you could only charge to 50% on a regular basis? Further, we don't necessarily know how Tesla's battery management comes into play. While putting a Tesla logo on a battery doesn't change the laws of physics or chemistry, we do know that there are controls in place to prolong life. So 80% as measured and reported by the charging circuit may not be the 4.05v per cell as tested in the article you referenced.

In fact, the article you referenced states "Industrial devices, such as the EV, typically limit the charge to 85% and discharge to 25%, or 60 percent energy usability, to prolong battery life.". Does that mean 100% as reported by the charging app is really 85% of battery voltage? I don't know.

So I don't disagree with your comment that charging to an actual cell level of 50% might be best, I just question whether doing so in our Teslas - as reported by the Tesla charging system - leads to the same benefit. And whether that benefit is significant enough to worry about.
Thank you for the elaboration and I agree with you. Note that we're talking about storing the car for an indefinite period to time. The generally accepted best practice is to set it to 50% and leave it plugged in. But the advantages of having 80% charge for emergencies or just peace of mind could easily outweigh the minor benefit of 50%.
 
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brucet999

Active Member
Mar 12, 2015
2,696
1,569
Huntington Beach, CA
I am 75 years old and am sheltering in place with no plans to drive for weeks, maybe a month. Should I charge my Model 3 every few nights or just wait until I plan to drive.
How is your electricity billed?

If you are billed on tiered rates, then you can leave it plugged in because it makes no difference when you charge.

If you are billed at time of use (TOU) rates, then you want to plug in at night when rates are low and charge to 80% or so. Let it run down to no less than 50% before charging again to be sure you have enough range for unforeseen eventualities.
 

Uncle Paul

Well-Known Member
Nov 1, 2013
6,299
7,596
Canyon Lake,CA
Technical people might give you other calculated answers, but I imagine a prudent person, in your circumstances, might just set your charge around 75% and not over think it. Of course, if you are planning a longer outing, perhaps charge up to 90% the night before.
 

erb2000

Member
Jan 3, 2020
15
39
Bedford, MA
You don't mention the SOC best for long term storage. There are dozens of articles and they all say 30% to 50% actual, with 40% being best. Since actual and displayed are different, you have to guess. 50% is a good guess for the Tesla.
 

Sans-gas

Member
May 1, 2019
127
52
NW WA
I am 75 years old and am sheltering in place with no plans to drive for weeks, maybe a month. Should I charge my Model 3 every few nights or just wait until I plan to drive.
Drive around, enjoy the scenery and sound system and charge it when it’s under 40%. That’s what I’m doing. I avoid contact with people, but enjoy the car too much to stay at home all the time.

I’m still “sheltering in place” but the place is sometimes my M3.

Be safe.
 

normd

Member
Mar 9, 2020
10
13
Waynesboro, VA
I read here that chemistry is chemistry, which is true, but from what I read the chemical com[position of the Tesla battery is different than that of an iPhone. So, how you manage our batteries is different than for an iPhone. Conditioning the battery is important every few months as described above but I am planning on charging when it get below 50% up to 80% for my convenience.
 

vickh

Active Member
Dec 16, 2018
3,149
709
az
If you only charge to 80% your batteries will become imbalanced over time. The only way to fix this is to leave the car above 85% SOC for days. People who have only been charging to 80% have seen reported capacity drop.

that imbalance is reversible though right?

50% is easy for those of us who don't have long commutes (a lot of people these days!)
 
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