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Can't charge at home. Optimal charging habits?

DopeGhoti

Active Member
Aug 28, 2019
1,277
1,466
Phoenix, AZ
I'm awaiting the arrival of a Model 3 LR/AWD, and am quite excited to be weaned off of gasoline. However, I live at an apartment, and cannot charge my car up overnight.

There is, however, a Supercharger near my workplace which I plan to use with a modicum of frequency, but I had a question about what's best for the battery:

I know they generally don't advise charging above 90% unless you're going to need the range. However, it's about a fifteen or twenty mile commute, which is about 5% of the rated 310 mile range. So would it be harmful to make it a habit of charging to 95% before driving home, putting the SoC at about 90% when I park for the evening? Or should I be only getting into the top 10% range when prepping for a long trip for which I need that extra ~30 miles of range?

Naturally, this question is notwithstanding how long it would take to get the stage of charge to 90%; I know that the fuller the battery is, the slower it is to take in more energy.
 
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Others might chime in with more info. Following is what I learned through this forum.
  1. Charge above 90% SOC only when planning for long trips.
  2. 80% SOC seems is be the general consensus.
  3. When parking outside all the time, be mindful of sentry mode, as it eats up the battery quickly compared to general battery drain that happens.
  4. Frequent supercharging is not advisable for long term battery health.
 
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Charging to 95% at a Supercharger takes a long time and therefore not cheap. Just charge to 80% at a Supercharger.
Look for charging options at work and don't forget that even a standard 120V plug can work for many people
Time is only a factor in certain states. Most places it is by kWh unless the state has certain utility rules that prevent selling by the kWh.
 

KenC

Active Member
Sep 4, 2018
4,859
4,628
Maine
I'm awaiting the arrival of a Model 3 LR/AWD, and am quite excited to be weaned off of gasoline. However, I live at an apartment, and cannot charge my car up overnight.

There is, however, a Supercharger near my workplace which I plan to use with a modicum of frequency, but I had a question about what's best for the battery:

I know they generally don't advise charging above 90% unless you're going to need the range. However, it's about a fifteen or twenty mile commute, which is about 5% of the rated 310 mile range. So would it be harmful to make it a habit of charging to 95% before driving home, putting the SoC at about 90% when I park for the evening? Or should I be only getting into the top 10% range when prepping for a long trip for which I need that extra ~30 miles of range?

Naturally, this question is notwithstanding how long it would take to get the stage of charge to 90%; I know that the fuller the battery is, the slower it is to take in more energy.
You can do it, but as has been mentioned, the SC charges slower at higher rates of SOC. Whether you actually need to be in the 90+% SOC range for trips, depends upon your situation. If you run simulations in abetterrouteplanner.com, you may find that charging to 90+% SOC makes little difference. For me, when I make regular trips south to Boston and beyond, I still have to stop at the same SC and charge up, a couple minutes more isn't a big deal.

As others have mentioned, you might look for a 120V outlet at your apartment that you could use, or one at work. For such a short commute, you don't need 240V, 120V will do.
 
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For the battery, without losing too much convenience, I'd charge to 90% and use the car until it was at 30% to 40%. There is a study that says STORING a battery for long periods (like a year) at 100% degrades the battery. 90% is better, and 80% is a little better than that. 50% is best. Hence, we don't like charging to 100% and letting it sit. In your case you'd at least be averaging well below 90% if you didn't charge every day. Which should be fine. This is approximately what I do when traveling and staying at a destination near a Supercharger.

I'd even be OK charging to 95% and driving it home to reach 90%. The problem is that it will take a while to Supercharge since it gets very slow above about 70%. While the Supercharger may be close to work, you'll have to find a way to start the car charging, walk back to work, and then walk back to the Supercharger and vacate the charger space when it's done. Maybe 45 minutes to an hour to charge 30% to 95%? It's kind of slow if you use it like a gas station. If you can get some shopping done or eat lunch the time might be inconsequential. Otherwise you might stick to 80% or less just for speed.
 
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I live in a condo and use a mix of free supercharging and level 2 free charging to get by. I drive nearly 2000kms per month and have had no issues. Sure I'd like to have the convenience of at home charging, even if it cost money, but I'm currently in the process of petitioning my strata (home owners association for you yanks). Its a slow process, so for now I've done just fine with charging at my gym, grocery store, and local supercharger. Ignore those who say supercharging will hurt your battery. Tesla used to give cars free supercharging and many long distance drivers relied mainly on that for energy. I'd just avoid charging above 90% unless strictly necessary.
 
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DopeGhoti

Active Member
Aug 28, 2019
1,277
1,466
Phoenix, AZ
While the Supercharger may be close to work, you'll have to find a way to start the car charging, walk back to work, and then walk back to the Supercharger and vacate the charger space when it's done.

I know I said there was a Supercharger close to work, but sadly it's not that close. If it were, I would indeed have just planned to "top up" as needed when the state of charge got low enough to warrant it.

Also, I may have not been clear in my intent, which was not to charge up to 95% to get home at 90% every day, but only when the time comes to require charging. I've long been in the (admittedly bad) habit of waiting for my ICE cars to turn on the 'Feed Me' light before refueling; I'm going to hopefully revise this habit to make somewhere in the 20-30% range my trigger for 'refueling', which for a LR Model 3 looks to be roughly in the '60-90 miles of capacity' range.
 
This is a little out of the box, but in your circumstance I would charge to 70% on the way home each day. You'll stay between roughly 55% and 70% each day (assuming the 20 mile commute is each way) which puts you in tier 1 ($0.14/minute). And it will take less than 15 minutes at the charging station.

For long trips, you don't even need to top up to depart from home. Going west, Buckeye Supercharger is less than 35 miles; Casa Grande is 50 miles east on I-10. Going north, Cordes Lakes is 63 miles.
 
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AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
14,914
19,266
San Diego
I know I said there was a Supercharger close to work, but sadly it's not that close. If it were, I would indeed have just planned to "top up" as needed when the state of charge got low enough to warrant it.

Also, I may have not been clear in my intent, which was not to charge up to 95% to get home at 90% every day, but only when the time comes to require charging. I've long been in the (admittedly bad) habit of waiting for my ICE cars to turn on the 'Feed Me' light before refueling; I'm going to hopefully revise this habit to make somewhere in the 20-30% range my trigger for 'refueling', which for a LR Model 3 looks to be roughly in the '60-90 miles of capacity' range.

I am going to assume your commute is 20 miles one way. Do you do it at 70mph?

If so, you’re going to use about 270Wh/mi/232Wh/rmi *40mi = 46rmi per day which is 15% of your battery.

So you’ll probably use more like 17-18% of your battery each day assuming no other driving. If you use any features like Sentry or Overheat protection (in Phoenix!) it’ll be more like 20-25% per day - perhaps you’ll be lower, if you have covered parking everywhere, though.

It may end up being even higher in summer - I have zero experience with how hard the car has to work to keep things cool in a very hot environment.

Just to calibrate you here.

Overall, not having a way to charge at home sounds painful. If your Supercharge is nice and you have something to do there that you would be doing anyway (grocery shopping or dining or something) it seems like it could work. Have you checked to see how busy they get? It seems like it is only going to get worse but who knows.
 
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DopeGhoti

Active Member
Aug 28, 2019
1,277
1,466
Phoenix, AZ
I am going to assume your commute is 20 miles one way. Do you do it at 70mph? If so, you’re going to use about 270Wh/mi/232Wh/rmi *40mi = 46rmi per day which is 15% of your battery.

I generally aim to cruise at ~68 MPH on the highway; I am more often than not in anything but a hurry (which is one reason that charging somewhat frequently doesn't strike me as a terrible burden).

So you’ll probably use more like 17-18% of your battery each day assuming no other driving. If you use any features like Sentry or Overheat protection (in Phoenix!) it’ll be more like 20-25% per day - perhaps you’ll be lower, if you have covered parking everywhere, though.

It may end up being even higher in summer - I have zero experience with how hard the car has to work to keep things cool in a very hot environment.

Just to calibrate you here.

Thanks for the more specific estimate. Given those numbers, it looks like I'm likely to be charging once a week or so. This is more often than I'd been gassing up, but that doesn't seem so terrible a burden. I've got books I've been meaning to read anyhow.

Overall, not having a way to charge at home sounds painful. If your Supercharge is nice and you have something to do there that you would be doing anyway (grocery shopping or dining or something) it seems like it could work. Have you checked to see how busy they get? It seems like it is only going to get worse but who knows.

I've noodled around the area and it doesn't usually seem too busy. One upside is that my parking at home and (usually) at work is covered, and my employer does have a few first-come-first-served EV charging spots, though they are only 120V, so I will at best recover one leg of my commute on the days that I get one of those spots.

I am going to approach my apartment complex's management to see if I can get them to expose one of the covered an outlets in the carport if I offer to cover the cost of the electrician and the electricity. Sadly, it's not feasible to fling an extension cord out of my window down to the carport. Even trickle-charging overnight would be helpful, if it can be arranged.
 
I'm awaiting the arrival of a Model 3 LR/AWD, and am quite excited to be weaned off of gasoline. However, I live at an apartment, and cannot charge my car up overnight.

There is, however, a Supercharger near my workplace which I plan to use with a modicum of frequency, but I had a question about what's best for the battery:

I know they generally don't advise charging above 90% unless you're going to need the range. However, it's about a fifteen or twenty mile commute, which is about 5% of the rated 310 mile range. So would it be harmful to make it a habit of charging to 95% before driving home, putting the SoC at about 90% when I park for the evening? Or should I be only getting into the top 10% range when prepping for a long trip for which I need that extra ~30 miles of range?

Naturally, this question is notwithstanding how long it would take to get the stage of charge to 90%; I know that the fuller the battery is, the slower it is to take in more energy.
This is gonna get old after the shine of the new car wears off. Typically charging to 90% takes 40-50 mins. I don’t supercharge often but that’s the sense I get when I’m road tripping and charging to stop to eat, walk, and shop.

There’s a youtuber teslajoy who has a condo and supercharges weekly since no charging at her home. Sometimes the tesla charging get full so she goes to a different supercharger 15 mins away and then charges while sitting in the car. It just seems annoying. Heck I love the car but I’d rather be doing something else besides sitting in a car charging every week.
 

DopeGhoti

Active Member
Aug 28, 2019
1,277
1,466
Phoenix, AZ
I'm seeing a lot of conflicting advice here and other places regarding the healthiness of using Superchargers with regularity. I'm glad to hear your anecdotal report that it is not a problem, and unless I see some solid advice to the contrary, am probably going to avail myself of the SC near my employer as needed until and unless I can arrange for a charging solution at home.
 

srs5694

Active Member
Jan 15, 2019
1,622
2,180
Woonsocket, RI
There’s a youtuber teslajoy who has a condo and supercharges weekly since no charging at her home.

Here's her main video on the subject:


I haven't watched it in a while, but I believe she relies on a combination of Superchargers and public Level 2 EVSEs, with the emphasis on the latter. That's an option that's not been given much emphasis in this thread, but IMHO it should be. In many areas, Level 2 EVSEs (mostly J1772 units, but some Tesla Destination sites) are fairly common, and if you'll be at a location for a while, they can be very useful. You can find these at some shopping malls, movie theaters, parks, downtown business districts, parking garages, etc. The single best resource I know for finding them is PlugShare. It provides a filter for plug type -- set it for Tesla (Destination and/or Supercharger) and J1772 to find the stations you can use in your area.

You might also want to consider buying Tesla's CHAdeMO adapter. This will enable you to use CHAdeMO DC fast chargers, which are slower than Superchargers but faster than Level 2 EVSEs. At $450, the adapter isn't cheap, but if you're relying on public charging infrastructure, it could be very useful, particularly if there happen to be CHAdeMO stations at malls or something near you. Again, use PlugShare to find CHAdeMO stations near you to help you assess whether it might be worth buying the adapter.
 
I felt the same way when I received my car. I lived in an apartment in LA so home charging just wasn’t and option. All I heard from other users was that supercharging would kill my battery, yet no one that advised against it had ever had a battery significantly decay from overuse of supercharging, or had even used supercharging as a primary means of fueling up. So I decided to bite the bullet and try it out. Since then I have used the car to travel around the country multiple times.
I have never run out of battery and have only had trouble finding chargers in extremely remote areas like along the Mexican/Texan border. I have plugged into J1772s less then 20 times, everything else has been through Superchargers. I just checked my mileage efficiency and yup, it’s still at 100%. I have never regretted not having a Chademo adapter. I have actually only come upon a chademo once where there was not a Supercharger right next to it. If you’re caught without a Supercharger, a J1772 adapter and the plug that comes with the model 3 (for me) has been more than enough. Like I said, it’s been less than 20 times in 90000 mi that I’ve had to resort that.

This is all anecdotal, but I don’t think Tesla would be releasing a mass market car knowing that so many city dwellers needing a public charger for primary use if that would kill the battery. I think the most important part is stopping it at 80-90%. I’ve had clear skies sticking with that rule.
 

joebruin77

Active Member
Dec 23, 2018
1,319
1,281
Encino, CA
For the first few weeks I had my Tesla, I did not have a home charger. I used the app Plugshare to find local J1772 charges and they were plentiful. Many of them were free. I also have the app EV Match: https://www.evmatch.com/ . This app lets you find private home owners who are willing to let you charge at their home charger for a small fee. You can even use the app to make an appointment or reservation to use the charger so you know it will be free when you need it.
 
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