When to start charging?

[kithytom]

I couldn't find anywhere from Tesla what is the best practice when it comes to charging.

Let's say I don't need to worry about range (all trips are short) and I have access to charging every night in my garage.
When Model Y drops to what percentage should I start to charge? Below 25%, 20%, 15%, or doesn't matter at all?

 

[jjrandorin]

I couldn't find anywhere from Tesla what is the best practice when it comes to charging.

Let's say I don't need to worry about range (all trips are short) and I have access to charging every night in my garage.
When Model Y drops to what percentage should I start to charge? Below 25%, 20%, 15%, or doesn't matter at all?

The very short answer would be to set it to 50% and charge it daily. There is no (none) benefit at all to "run it down before charging it back up". You wont find any guidance from tesla other than "plug it in and charge somewhere on the slider".

What you WILL find, however, are probably 100+ threads and 1000+ posts here on the general topic.

 

[Sophias_dad]

What you WILL find, however, are probably 100+ threads and 1000+ posts here on the general topic.

You mean 101+ threads, now

 

[BitJam]

I agree with @jjrandorin except some people recommend charging to 60% rather than 50%. In addition, I recommend using scheduled charging to charge in the middle of the night even if your electricity rate is not cheaper at night.

Here are some answers from Tesla:

Home Charging - Frequently Asked Questions

Learn more about how to charge a Tesla at home, including home charger installation costs, equipment options and how long it takes to fully charge a Tesla battery.

www.tesla.com

What's a best practice for charging a Tesla at home?
We recommend plugging in every evening to top off the battery.

Should I wait for the battery to fully deplete before charging?
Tesla uses lithium ion batteries so there is no memory effect, this means there is no need to deplete the battery before charging. We recommend plugging in as often as possible.

 

[jjrandorin]

I agree with @jjrandorin except some people recommend charging to 60% rather than 50%. In addition, I recommend using scheduled charging to charge in the middle of the night even if your electricity rate is not cheaper at night.

Here are some answers from Tesla:

Home Charging - Frequently Asked Questions

Learn more about how to charge a Tesla at home, including home charger installation costs, equipment options and how long it takes to fully charge a Tesla battery.

www.tesla.com

What's a best practice for charging a Tesla at home?
We recommend plugging in every evening to top off the battery.

Should I wait for the battery to fully deplete before charging?
Tesla uses lithium ion batteries so there is no memory effect, this means there is no need to deplete the battery before charging. We recommend plugging in as often as possible.

If someone doesnt have TOU rates, and is charging on a 120v connection (Like a regular outlet), it would be better for them to charge right when they get home from driving, so the battery was still warmer (especially in the winter), even if that was during the day instead of at night.

I do agree with using scheduled charging in general though, as well as, in general, charging at night unless there are extenuating circumstances (using 120v, wanting to charge while the sun is up because of having solar, etc).

 

[jcanoe]

I couldn't find anywhere from Tesla what is the best practice when it comes to charging.

Let's say I don't need to worry about range (all trips are short) and I have access to charging every night in my garage.
When Model Y drops to what percentage should I start to charge? Below 25%, 20%, 15%, or doesn't matter at all?

You did not state whether you will be charging at 120 volts (Level 1) or 240 volts (Level 2). Level 1 charging in winter can be hampered by the cold. With Level 1 charging it is best to plug in and start to charge as soon as you arrive home since the battery will be warm from the drive. When charging using Level 1 it is not unusual to use all available time when parked at home to charge the Tesla Model Y, be ready for the next day's driving.

If you are charging using Level 2 (240 volts) then you can set up Scheduled Charging to start charging at a specific time. This is useful if your electric utility offers a time of use (TOU), off-peak rate plan. You can also set the Tesla Model Y to always complete charging just prior to you leaving in the A.M. This will help ensure that the battery is already warm (from the charging session) and improve efficiency when warming the passenger cabin.

 

[MacO512]

The very short answer would be to set it to 50% and charge it daily. There is no (none) benefit at all to "run it down before charging it back up". You wont find any guidance from tesla other than "plug it in and charge somewhere on the slider".

What you WILL find, however, are probably 100+ threads and 1000+ posts here on the general topic.

Good post. I'd just add that feel free to skip charging some of the days when it's inconvenient, it's just not a big deal either way.

 

[MacO512]

Doesn't level 1 charging cost more because it's an unbalanced load? Doesn't really matter with appliances but with a.car charging hundred of hours a month I doubt the homeowner has close balance across both phases most of that time.

Of course level 1 also costs more cause car can't sleep as much.

 

[jjrandorin]

Good post. I'd just add that feel free to skip charging some of the days when it's inconvenient, it's just not a big deal either way.

Absolutely!

If someone has home charging and its easy to plug in, plug in. If its not easy to plug in (need to rotate cars, etc) or one doesnt have home charging, its perfectly fine to run it down before charging if that is what works.

From your post I can tell you know this, but for the threads sake, I will say my advice was in the context of what was asked, which is someone with home charging, trying to figure out how low they "should" run the battery down before they charge it back up. If its more convenient to run it down, or charge every 3rd day, have at it, for anyone reading.

Its just not necessary to run it down (and its not necessary to plug it in daily either).. do what works for each person.

 

[jjrandorin]

Doesn't level 1 charging cost more because it's an unbalanced load? Doesn't really matter with appliances but with a.car charging hundred of hours a month I doubt the homeowner has close balance across both phases.

Of course level 1 also costs more cause cat can't sleep as much.

I dont know about the load, but the issue with level 1 charging (in the US) is that the car being awake is X amount of overhead on the charging rate, which as a percentage of level 1 charging on 15amps is a fairly decent sized chunk. Its enough that its possible for a car that is parked in the cold to be plugged into a level 1 circuit thats 15amps, and not be able to charge at all because all the electricity is going to heat the battery.

with level 2 charging (of basically any amps) that "car awake" overhead is the same amount of energy but a much lower percentage, so it makes less of a dent in the overall charging. The faster you charge (level 2) the faster the car can go back to sleep and stop that "car awake" overhead, so less overall energy used.

 

[E90alex]

Everyone you ask will have a different opinion.

Teslas official stance is simply keep it plugged it in as often and as long as possible and set the limit no more than 90% for daily use.

Personally I only use about 12-15% of battery for my daily commute. I set charge level to 55% and charge it every night. I also set “off peak” charging even though I don’t have off peak electricity rates so that it finishes charging right before I leave in the morning so the battery doesn’t cool off overnight and have to warm up again.

 

[ucmndd]

Doesn't level 1 charging cost more because it's an unbalanced load? Doesn't really matter with appliances but with a.car charging hundred of hours a month I doubt the homeowner has close balance across both phases most of that time.

Why would an “unbalanced load” cost more? A kilowatt hour is a kilowatt hour.

 

[MacO512]

Why would an “unbalanced load” cost more? A kilowatt hour is a kilowatt hour.

I've heard electricians can save hundred a month for schools or commercial buildings
by moving breakers to balance the load. I'm not sure if that applies to some or all or very little residential 120/240 volt systems. The basis of it I believe is that meters only measure amps then calculate that at 240 so if it's all on one leg it's basically twice the cost as split even.

 

[MacO512]

Ok just googled it some more, appears that balancing doesn't save money for 120/240 volt systems, but it would reduce current on electrical wires, the neutral wire, and avoid having to upgrade service.

 

[Benito1283]

Plug in whenever you can. When you drive a bunch and then park (w/o plugging in), you often lose 1-2% battery to vehicle standby before the car goes to sleep. Do this 50-100 times and you've used a complete battery cycle. I've lost up to 4% standby in very hot weather - I assume from cooling things before going to sleep.

 

[kithytom]

Thanks all for the inputs on this repeatly discussed topic.

I’m in NorCal not much cold temp situation and no TOU so no optimal time and using Nema 14-50 @ 32A. Here is what I’m planning moving forward.

Set charge limit to 60%.​

Whenever battery drops below 15%, start charge immediately after park since it’s still warm.​

No charge if above 15% and no need for range in upcoming trips.​

 

[Benito1283]

I’m not sure how you concluded about waiting to 15% to charge. Everyone is suggesting not to let it get that low to charge. There’s no benefit. Rather, the lower the average depth of discharge, the better for long-term battery health. In other words, plug it in as often as you can.

 

[jcanoe]

Thanks all for the inputs on this repeatly discussed topic.

I’m in NorCal not much cold temp situation and no TOU so no optimal time and using Nema 14-50 @ 32A. Here is what I’m planning moving forward.

Set charge limit to 60%.​

Whenever battery drops below 15%, start charge immediately after park since it’s still warm.​

No charge if above 15% and no need for range in upcoming trips.​

Many Tesla owners do not regularly discharge the battery below 20% unless on a trip and will be stopping at a Supercharger (< 20% SOC along with Preconditioning for Supercharging ensures the fastest Supercharging session.) When the battery SOC is at or below 20% the Tesla Model Y will automatically display a notice on the screen that you should plug in and charge (this message cannot be turned off, gets to be annoying.) Also, below 20% SOC maximm power to the drive unit(s) is reduced, Sentry Mode is disabled along with Cabin Overheat Protection.

If 60% is your target SOC then consider maintaining the battery between 50% and 60%, or 40% and 60%.

I would suggest setting an off-peak rate window that ends at 0600 or 0700 (even though you are not currently on a TOU rate plan.) The utility power demand is generally lower between midnight and 0630 so you would be helping reduce the need for additional power generation if you charge, complete charging during this time.

When you charge the Tesla Model Y the battery pack is warmed from the charging session. If you leave at approximately the same time, Monday through Friday, this would be shortly after the charging session completes. You can set the Climate Control Preconditioning to always precondition the passenger cabin to your desired temperature by the time you normally leave for your commute. The Tesla Model Y heat pump will be able to direct warm coolant from the battery pack to help warm the passenger cabin using less energy to warm the passenger cabin than if the battery pack was cold.

 

[BitJam]

No charge if above 15% and no need for range in upcoming trips.

In terms of longevity, letting the battery get too low is just as bad as letting it get too high. Batteries are happiest around 50% which is why only charging to 50% or 60% is recommended. Keeping the battery between 40% and 60% would be ideal. Letting it go down to 15%, not so much. I imagine it is roughly the equivalent of charging up to 85%.

 

[kithytom]

I’m not sure how you concluded about waiting to 15% to charge. Everyone is suggesting not to let it get that low to charge. There’s no benefit. Rather, the lower the average depth of discharge, the better for long-term battery health. In other words, plug it in as often as you can.

From personal experience of having a 2017 Model X. Five years and 48k miles, the battery degraded enough to a point where Tesla had to replace them in Octorber 2022 (under warrenty). The charging routine was: limit always set to 90% unless road trip, charge whenever parked at home (Wall Connector Gen 1). I think a few possible factors that led to this battery degradation:

1. Charge limit of 90% was too high for 2017 Model X.
2. Charge whenever parked at home (often charged when battery was above 50%).
3. Bad qulity.
4. Technology was still experimental at that time.

I can only control the first two factors. Since 90% is within Tesla's recommended limit for Model Y, this leaves me the only option to experiment factor 2. Since there is no harm (official confirmation from Tesla) to charge at this low level, I am going to try it given my miserable experience prior.