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Work-from-home/Pandemic charging practices

Picking up my MY later this week, I am so happy! I've read up on all the information/posts about why we charge and even the real geeky electrical engineering stuff of romex, outlets, and wall connectors. Apologies if this has been asked before; I tend to post about specific situational questions.

I work from home Mon-Fri (random trip to Costco or post office during lunch) and Sat-Sun is usually cover band gigs, other errands, or going somewhere with the wife. So I hardly travel away from the house during the week. I will be using the 20A outlet in my garage; I am firmly opting not to install a 50A outlet nor the HPWC because we are moving in 6-8 months. Sentry Mode and Cabin Overheat will probably be off most of the time, especially at home. No need and it's starting to get colder out in NJ. I might do the other stuff like precondition the car/warm the cabin and seats up before heading out somewhere.

My question to optimize/maximize the battery's lifespan is: With my Tesla mostly sitting for 5 days a week, should I leave it charging in my driveway day and night because I can OR should I leave it disconnected and do my thing until I get down to ~20% and just fill 'er up to 80% again?
 

cgell

Member
Supporting Member
Jan 30, 2020
442
598
NJ
Picking up my MY later this week, I am so happy! I've read up on all the information/posts about why we charge and even the real geeky electrical engineering stuff of romex, outlets, and wall connectors. Apologies if this has been asked before; I tend to post about specific situational questions.

I work from home Mon-Fri (random trip to Costco or post office during lunch) and Sat-Sun is usually cover band gigs, other errands, or going somewhere with the wife. So I hardly travel away from the house during the week. I will be using the 20A outlet in my garage; I am firmly opting not to install a 50A outlet nor the HPWC because we are moving in 6-8 months. Sentry Mode and Cabin Overheat will probably be off most of the time, especially at home. No need and it's starting to get colder out in NJ. I might do the other stuff like precondition the car/warm the cabin and seats up before heading out somewhere.

My question to optimize/maximize the battery's lifespan is: With my Tesla mostly sitting for 5 days a week, should I leave it charging in my driveway day and night because I can OR should I leave it disconnected and do my thing until I get down to ~20% and just fill 'er up to 80% again?
Based on the fact that you are going to use a 20amp and that your vehicle will be warming up during winter you may want to charge more often. Waiting until 20% is cutting it close and ideally you don’t want the battery getting below 30% when you can avoid it. You can leave it plugged in, but the only question would be the weather since it will be outside.
 
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I work from home, and sometimes drive as little as 3 miles a day. I keep my charge limit at 70% usually. I honestly don't always plug it in, unless I go below 50%. Prior to weekend I might set the charge limit to 80%, and prior to long trips I will charge to 100% the night before.

That said I think something like 50-70/80% is more optimal than 20-80%, and plugging it in is always more optimal than not plugging it in.
 
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jcanoe

Well-Known Member
Oct 2, 2020
6,723
7,605
Maryland
If it not too much trouble, i.e. moving the Tesla Model Y into the garage, then leave the Tesla plugged in. If you don't plug in every day nothing bad will happen. (One reason not to leave the Tesla vehicle plugged in all the time when parked at home is ground strike lightning and power surges during or after electrical storm outages.) I always unplug my Tesla if there are thunderstorms in the local forecast or when lightning is within 10 miles of my location.

I have charged my Model Y using a 20A circuit. The 20A will add ~5% of charge to the battery per hour or 12 to 14 miles or driving range. Figure out how many hours it would take to go from 70% etc. to the 90% state of charge that you would want to charge to before leaving on a longer drive or trip. For me that defines the lowest state of charge that I am comfortable letting the battery go down to before charging. In this example to bring the battery from 70% to 90% before leaving on a trip would take ~4 hours of charging using Level 2 240V/20A charging

If you precondition before driving, especially in winter, this will not show up in your driving efficiency as part of the Wh/mi efficiency number but it will sap the battery unless the Tesla is plugged in during preconditioning. My experience based, on last winter here in Maryland, is that I used almost as much energy preconditioning the Tesla vehicle (four times a day most days) as I did driving the Model Y. I typically drive less than 15 miles per day.
 
Thank you everyone for chiming in so far. I don't have the luxury of keeping the MY in my garage (too much stuff ha!) so I will just run the mobile connector from the outlet to under the garage door and outside to the vehicle. I've read that the connector cable is robust enough to be "sat on" by something like a garage door.
 
I work from home, and sometimes drive as little as 3 miles a day. I keep my charge limit at 70% usually. I honestly don't always plug it in, unless I go below 50%. Prior to weekend I might set the charge limit to 80%, and prior to long trips I will charge to 100% the night before.

That said I think something like 50-70/80% is more optimal than 20-80%, and plugging it in is always more optimal than not plugging it in.

Your situation is very similar to mine so I'll try following that 70/80/100% practice for charging my vehicle! And Jcanoe advice to disconnect it during thunderstorms sounds like a good idea too.
 
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I work from home, and sometimes drive as little as 3 miles a day. I keep my charge limit at 70% usually. I honestly don't always plug it in, unless I go below 50%. Prior to weekend I might set the charge limit to 80%, and prior to long trips I will charge to 100% the night before.

That said I think something like 50-70/80% is more optimal than 20-80%, and plugging it in is always more optimal than not plugging it in.
That's my pattern as well - I can't leave my car plugged in 24/7 (I have to lay it across a sidewalk with a cord cover...not ideal but it's the card I'm dealt), so I plug it in below 50%, with the charge limit set to 70%; if I know I'm going to be driving, say, >30 miles that day, I'll move it to 80. On a 5-20 outlet, I get about 6 miles per hour, which reliably gets me about 20% overnight.
 
Relating specifically to long term battery longevity and your driving regime follows are my thoughts. The HV traction battery optimum SOC level is probably between 40 to 50 percent; likewise, the less fluctuation in SOC leads to longer battery life. The 12V battery will also last longer when kept closer to the float voltage level and minimizing low depth of charge levels. Given the above, I would set the charge level to 50% and leave the car plugged in so it can top off to 50% automatically. When the car is not awake for other reasons, it will top off the HV battery after dropping around 3% battery capacity. If the car is awake for other reasons (Sentry Mode etc..) , I have read that it will top off maybe once an hour or more (why not top off the both batteries while awake every 15 minutes)? Not sure if the car tops off the HV battery when it wakes from sleep to top off the 12V battery (makes sense if it did from a charging cost perspective)? When parked over several days, my car sleeps approx 17 hours then wakes up for approx two hours to top of the 12V battery then rinse and repeat. I can't see any reason why topping off the HV (assuming you a plugged in) and 12V batteries during that two hour window does not make sense? Some of the above could have changed; therefore, If any of the above is incorrect or I left out anything pertinent to what I discussed please chime in.

Regards, Ron
 
I just returned from a trip where my Model Y was left parked in my home garage from Tuesday evening through the following Tuesday morning, ~ a full week. My Model Y was left unlocked, not plugged in. No sentry mode (never when parked in my home garage.) Had 70% SOC when I left, 69% SOC when I returned.
Awesome data point, thanks. Did you wake it up via mobile app much?
 
If it not too much trouble, i.e. moving the Tesla Model Y into the garage, then leave the Tesla plugged in. If you don't plug in every day nothing bad will happen. (One reason not to leave the Tesla vehicle plugged in all the time when parked at home is ground strike lightning and power surges during or after electrical storm outages.) I always unplug my Tesla if there are thunderstorms in the local forecast or when lightning is within 10 miles of my location.

I have charged my Model Y using a 20A circuit. The 20A will add ~5% of charge to the battery per hour or 12 to 14 miles or driving range. Figure out how many hours it would take to go from 70% etc. to the 90% state of charge that you would want to charge to before leaving on a longer drive or trip. For me that defines the lowest state of charge that I am comfortable letting the battery go down to before charging. In this example to bring the battery from 70% to 90% before leaving on a trip would take ~4 hours of charging using Level 2 240V/20A charging

If you precondition before driving, especially in winter, this will not show up in your driving efficiency as part of the Wh/mi efficiency number but it will sap the battery unless the Tesla is plugged in during preconditioning. My experience based, on last winter here in Maryland, is that I used almost as much energy preconditioning the Tesla vehicle (four times a day most days) as I did driving the Model Y. I typically drive less than 15 miles per day.
I'm concerned on what you said.... if Im not in the house and left my car plugged.... what happened if there is a electric storm coming and not able to come home to unplug it???
 

jcanoe

Well-Known Member
Oct 2, 2020
6,723
7,605
Maryland
I'm concerned on what you said.... if Im not in the house and left my car plugged.... what happened if there is a electric storm coming and not able to come home to unplug it???
Probably nothing bad would happen if the power goes out during an electrical storm while the Tesla vehicle is plugged in. There is a chance, however small, of a close by lightning strike passing a very large voltage through the home's wiring. This could damage anything in its path. I have had the following equipment damaged over the years: television, laptop and surge protector power strip (the inside was just crispy critters inside after a close lightning strike.)

Ham radio operators have been dealing with the risk of lightning striking radio antennas and damaging the equipment ever since radio was invented. The best method of protecting electronics from damage due to lightning and voltage surges that can occur when power is restored is to unplug anything that could be damaged by a power surge. Antenna connections can be quickly disconnected and even dropped outside the home until the storm threat of has past.
 

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