Is there any benefit to charging at a lower amperage over night?

[Vicj]

Hello. I have a Tesla Wall charger, and faithfully plug in nightly, recharging at 48 Amps. I start charging at midnight, when the rates drop precipitously.
I was wondering if there's any actual benefits to charging at a lower amperage, as the app allows...say 32amps, instead of 48. Or even 24. I know it will take longer, but that's not an issue for me.
Thoughts from an expert?

 

[outdoors]

Optimal Charging Amperage

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...

teslamotorsclub.com

Thoughts from a good thread.

Mine are that the lower the amps overhead will depending on your car, can reduce your efficiency of your charging session. The car will consume a basic overhead amount of energy because it is on and awake while charging.

If you shorten that time and charge at a higher amperage within reason the car will charge then go back to sleep. The goal would be try to time that charging to coincide with your departure.

I am by no means an expert, but slept in my car last night and didn't stay at a holiday inn express.

 

[Vicj]

I never use the Departure feature, as my departure times vary greatly, and sometimes I don't drive it at all on a particular day. I charge to 85% so, just wondering is charging slower adds any density or anything to the battery

 

[zecar]

Probably not. 11.5kw is slow charghing for a big pack. Lower average state of charge over many years probably makes some difference

 

[Ohmster]

I reduce from 48 to 36. No data or facts to support this habit. Too low may have overhead loses and too high other issues. Don’t know if 36 or 48 clear either.

Do check your rates though. We are on a Time Of Use plan that has a non-intuitive off peak slot. Ours is not midnight but 8AM!

 

[sleepydoc]

Supposedly Tesla limited the number of high-power supercharging sessions a battery can have in its lifetime Which tells me that higher current can shorten batter life. Now that involves significantly higher currents than home charging (Superchargers go up to 250 kW which would be over 1000A on a home 240V circuit)

In general, the car will monitor battery temperature and state of charge and manage the charging rate to optimize charging for the current battery condition so I don’t think it’s anything you need to worry about. That’s probably what you’re seeing when you see ’the rate drop precipitously.;

 

[North75]

Supposedly Tesla limited the number of high-power supercharging sessions a battery can have in its lifetime Which tells me that higher current can shorten batter life. Now that involves significantly higher currents than home charging (Superchargers go up to 250 kW which would be over 100A on a home 240V circuit)

In general, the car will monitor battery temperature and state of charge and manage the charging rate to optimize charging for the current battery condition so I don’t think it’s anything you need to worry about. That’s probably what you’re seeing when you see ’the rate drop precipitously.;

250 kW would be over 1000A at 240V. So way higher current. It’s over 20 times more power then 48A at 240V

 

[sleepydoc]

250 kW would be over 1000A at 240V. So way higher current. It’s over 20 times more power then 48A at 240V

oops! Dropped a zero. Thanks for the catch - fixed it.

 

[jcanoe]

Hello. I have a Tesla Wall charger, and faithfully plug in nightly, recharging at 48 Amps. I start charging at midnight, when the rates drop precipitously.
I was wondering if there's any actual benefits to charging at a lower amperage, as the app allows...say 32amps, instead of 48. Or even 24. I know it will take longer, but that's not an issue for me.
Thoughts from an expert?

Somewhere there is information that Level 2 charging (240V) and 40A is slightly more efficient than either 48A or 32A, etc. Any Level 2 charging is 7X, even up to 20X lower charging level than Supercharging. Level 2 charging is so much lower power level than Supercharging that none of the Level 2 charging amperage settings would stress the battery.

In terms of efficiency, using the Scheduled Departure settings (especially in winter) so that the charging session completes in the early A.M. shortly before you leave home (assuming you commute to your workplace) is the more efficient way to charge at home. The battery will already be warm from the charging session and the Tesla vehicle will not need to draw additional power to warm the battery.

 

[Vicj]

As I mentioned earlier in the post, I don't use scheduled departure. I don't leave at the same time every day, and resetting it every evening is a pita.

 

[jcanoe]

Once warmed the battery will retain heat for many hours. Scheduled Departure set to complete complete charging by 0600 or so each day would provide at least a partially warm battery for driving anytime of the day. In many places, for approximately 6 months of the year, this puts otherwise wasted heat energy from charging to use.

 

[Rocky_H]

From the car's battery perspective, no, it's made to handle much more than that. But for the long term life of your external charging equipment, like the wall connector, I might turn it down some, like into the mid 30's or low 40's. It's rated for a maximum of 48A and can heat up and get pretty warm there. That daily heat cycle of hot/cold/hot/cold causes metals to expand and contract and is the kind of thing that stresses solder joints and electronics over time. So if the extra charging speed isn't needed every single time, I would keep mine a little cooler if I could to make the equipment last longer.

 

[xyeahtony]

no. Just charge as you please. Honestly micromanging the charging of your battery might or can improve battery life by 1% or so, but its not going to make any big difference. you're likely to sell your car before the battery suffers any meaningful degradation. Even battery packs with 200k+ miles and hundreds of supercharge sessions still have over 80% of their original capacity.

 

[thesmokingman]

Lower amperage is less efficient actually. There's a chart that details it. Around 6-7kw you get into the 90s and the max efficiency is 11kw.

 

[D Moore]

From the car's battery perspective, no, it's made to handle much more than that. But for the long term life of your external charging equipment, like the wall connector, I might turn it down some, like into the mid 30's or low 40's. It's rated for a maximum of 48A and can heat up and get pretty warm there. That daily heat cycle of hot/cold/hot/cold causes metals to expand and contract and is the kind of thing that stresses solder joints and electronics over time. So if the extra charging speed isn't needed every single time, I would keep mine a little cooler if I could to make the equipment last longer

 

[D Moore]

good points and advice.

 

[Iron]

As I mentioned earlier in the post, I don't use scheduled departure. I don't leave at the same time every day, and resetting it every evening is a pita.

Set it to earliest time you'll leave and leave it there.