Optimal Charging Amperage

[SNYDERHAUS]

I just picked up my Tesla today and had a few questions about charging that I can’t seem to find online (let’s face it, Quora is just a bunch of opinions, hehe)

I have the Tesla Wall Charger on a 60amp circuit. I know that Tesla has active battery heating and cooling to optimize the charging and discharging, but I was wondering what is the optimal amperage to charge the car?

Can I use all 48amps and let it charge sooner, does the active heating/cooler keep it stable so there’s no degradation? Or for longevity of the battery am I better at keeping the charger set to 15amps or so and charge that way over night?

Any insights are appreciated!

 

[charlesoris]

48A will do fine.

 

[bruce4000]

I set mine so it charges midnight to 6 am so off peak and do enough to cover my daily driving. In my case I only need at 20 amps.

 

[MY-user]

I just picked up my Tesla today and had a few questions about charging that I can’t seem to find online (let’s face it, Quora is just a bunch of opinions, hehe)

I have the Tesla Wall Charger on a 60amp circuit. I know that Tesla has active battery heating and cooling to optimize the charging and discharging, but I was wondering what is the optimal amperage to charge the car?

Can I use all 48amps and let it charge sooner, does the active heating/cooler keep it stable so there’s no degradation? Or for longevity of the battery am I better at keeping the charger set to 15amps or so and charge that way over night?

Any insights are appreciated!

Slow charge overnight 15-20 amps. Use scheduled departure feature on your app.

 

[jjrandorin]

Slow charge overnight 15-20 amps. Use scheduled departure feature on your app.

ALL home charging is "slow" and there is no difference to the car between 15-20 amps and 48amps (none). The only difference in slowing it down is keeping the car awake longer (thus using more energy because the car is awake longer).

 

[Big Earl]

The slower you charge, the less efficient it will be due to fixed overhead loads and heat loss (mostly a winter phenomenon). There is no longevity benefit to charging more slowly than 48 amps.

 

[MY-Y]

I believe that 48 Amps charges a bit more efficiently than lower amperage. No reason not to use 48 if you've got it. It's a trickle compared to the super charger that the batteries are designed for.

 

[MY-user]

ALL home charging is "slow" and there is no difference to the car between 15-20 amps and 48amps (none). The only difference in slowing it down is keeping the car awake longer (thus using more energy because the car is awake longer).

The energy to keep the car awake longer is minimal. Also what's the point of charging at 240v 48amps to 80% in the evening and let the car sit charged and lose 2-3% by morning? It's more practical to use scheduled departure and charge for 8-10 hrs. at 15-20amps.

 

[jjrandorin]

The energy to keep the car awake longer is minimal. Also what's the point of charging at 240v 48amps to 80% in the evening and let the car sit charged and lose 2-3% by morning? It's more practical to use scheduled departure and charge for 8-10 hrs. at 15-20amps.

No, its not (and the car doesnt lose 2-3% by morning). Awake car = 1-2 miles of drain per hour. Not awake car = 1-3 miles of drain per day. The fact that you say "lose 2-3% a day" is because you are keeping your car awake longer.

 

[MY-user]

The fact that you say "lose 2-3% a day" is because you are keeping your car awake longer.

Probably, and I also never turn off Sentry Mode.

 

[jjrandorin]

One more thing... the purpose of scheduled charging was intended to be so that you could get either the car or the battery warm, so you would use less energy heating those things on the road, if you need that extra range. The best thing for energy use is to charge the car as fast as home charging can go, but have it finish before you leave. Thats optimal.

Failing that, its most efficient to charge as fast as your home charging allows. Its not worth it to upgrade panels and incur thousands of dollars of expense to charge faster, but there is no reason to "turn it down" at all.

 

[Quagmire2]

The energy to keep the car awake longer is minimal. Also what's the point of charging at 240v 48amps to 80% in the evening and let the car sit charged and lose 2-3% by morning? It's more practical to use scheduled departure and charge for 8-10 hrs. at 15-20amps.

Or use scheduled departure and still charge at 48A and the car will charge the battery to have the car ready by the set departure time. Also tell it when is your off peak hours so it will charge it during the off peak hours as well.

 

[Big Earl]

Probably, and I also never turn off Sentry Mode.

If you never turn off Sentry Mode, then it doesn’t matter how fast you charge. Do whatever floats your boat but be prepared for your state of charge estimation to drift over time due to the car not being able to sleep.

 

[SNYDERHAUS]

I just want to say thanks for all the comments! I appreciate the insights being a super Tesla noob.

 

[MY-user]

Or use scheduled departure and still charge at 48A and the car will charge the battery to have the car ready by the set departure time.

Yes, in a perfect world but:
- if you leave your home an hour early then your car might not have enough charge.
- Tesla app is a POS and will fail you a couple of times per month. If you charge at low amp then in the morning you will still have a chance to crank it up to 48 amps and get a decent amount of energy.

 

[MY-user]

The best thing for energy use is to charge the car as fast as home charging can go, but have it finish before you leave. Thats optimal.

Are we talking about $0.07 per night? Let's not focus on it too much.

Its not worth it to upgrade panels and incur thousands of dollars of expense to charge faster,

Agree 100%

but there is no reason to "turn it down" at all.

There are a lot of reasons but they are not related to efficiency.

 

[jjrandorin]

There are a lot of reasons but they are not related to efficiency.

Nor battery health, battery degradation, etc (all home charging is slow charging, to the car, so anything you read about fast vs slow charging does not apply to "only" 48amps charging on a model 3/Y, which can take up to 250amp directly).

As far as your sentry mode use, if you never turn off sentry mode, its going to be an additional 9,000-11,000 "miles" of usage on your battery, just sitting there, so if you drive 10k miles a year, your battery will have discharged approximately 20k miles worth of energy, or basically double the cost.

That is your choice, and I am not faulting you for it, but this OP mentioned most efficient, so there is nothing about efficiency that says "turn down the speed". There also isnt anything about battery degradation. There could be convenience in timing charging, but there are other ways to do that too.

 

[MY-Y]

My car starts charging around 5:00 in the morning at 48 amps. It hits 80% at 6:30 when I'm ready to leave. Power is cheap then, and the battery is more warmed up than a slower longer charge. If you've got 48 amps, enjoy the benefits of it.

 

[MY-user]

My car starts charging around 5:00 in the morning at 48 amps. It hits 80% at 6:30 when I'm ready to leave. Power is cheap then, and the battery is more warmed up than a slower longer charge. If you've got 48 amps, enjoy the benefits of it.

Did Tesla app ever let you down? If you don't check the app around 5:30 then you might be surprised that your car is not charged. Not a big deal unless you drive a lot.

Nor battery health, battery degradation, etc (all home charging is slow charging, to the car, so anything you read about fast vs slow charging does not apply to "only" 48amps charging on a model 3/Y, which can take up to 250amp directly).

As far as your sentry mode use, if you never turn off sentry mode, its going to be an additional 9,000-11,000 "miles" of usage on your battery, just sitting there, so if you drive 10k miles a year, your battery will have discharged approximately 20k miles worth of energy, or basically double the cost.

That is your choice, and I am not faulting you for it, but this OP mentioned most efficient, so there is nothing about efficiency that says "turn down the speed". There also isnt anything about battery degradation. There could be convenience in timing charging, but there are other ways to do that too.

The energy is not expensive and if in 5 years I will truly benefit from Sentry mode then I say it's worth it. As far as adding 10k per year, I think it's less. It consumes about 6% per day. I just did the math. It's closer to 7k. Still much more than I thought it would add up. In the end, I purchased the car to enjoy everything it's got to offer. Warm steering wheel in the winter, Preconditioning, safety, acceleration, etc. If I didn't want these features I'd be driving another car that costs 1/2 as much.

 

[Quagmire2]

Yes, in a perfect world but:
- if you leave your home an hour early then your car might not have enough charge.
- Tesla app is a POS and will fail you a couple of times per month. If you charge at low amp then in the morning you will still have a chance to crank it up to 48 amps and get a decent amount of energy.

I have yet to run into an issue of the app refusing to set scheduled departure. If you do, just program it directly in the car.