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Does a model S 90D really charge this slowly?

Billbrown1982

TM3 LR 2021 | Red | FSD
Dec 21, 2020
611
351
Basildon
So, i've got a 90D as a courtesy car while my 2021 model 3 is being repaired. Never had a Tesla before so I only know the speeds that I get from my 3.

At work we have a piddly 4kw charger. But I know that if I stick my car on there and go out and do a 10 hour shift, it will be full when I get back, regardless. It normally ends up charging a lot quicker than it says it will actually.

I stuck this 90D on today for about 9 hours.....and it went from 30% to 60%

Is that normal for these? I checked that the charge wasn't limited in app or anything. I'm not really enjoying this car (although its better than nothing granted) but if this is the charging speeds i'm gonna get then my god I want mine back asap!
 
Probably about right.
My quick calculation... if you added 30% to a 90kWh battery that would have added 27kWh to the car. If the charger was giving the full 3kW for 9 hours that would give 27kWh, so unless the charging loss is 1kW (because your charger's a 4kWh charger) then it is about right. Sometimes, the charger is not giving the full 4kWh you expect, maybe only 3.6 or 3.7kWh.
 
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Physics at play.
tl;dr, they both charge at the same rate, but relative to each car, the same energy added is proportionally different for different size batteries and different driving efficiencies

Keeping numbers simple, approximate and not accounting for other variables 4kW for 10 hours will add 40kWh of energy.

Say a LR battery is 70kW, 40kWh is 57% of that battery, as it would be similar for a Model S 70.
For the 90, call it a 90kW battery, 40kWh is 44% of that battery.
Adding an SR+ to the mix, say 50kW battery, 40kWh is 80% of that battery
But its the same 40kWh of energy added at the same rate but is proportionally a different amount of % depending on the battery size.

More importantly...

Plucking numbers out of the air as its dependent on your circumstances. How far does that 40kWh get your car?
At 250Wh/mile, that 40kWh is going to get you 160 miles
At 350Wh/mile, that 40kWh is going to get you 100 miles

As the larger Model S loaner will be less energy efficient, you are likely to do higher Wh/mile than you might with a Model 3. So the 250Wh/mile above may be more representative of the Model 3 whilst the 350Wh/mile more representative of that Model S loaner. Same amount of energy, same amount of time to charge, but it will get you different distances depending on how efficient your car is, what the weather is and how you drive et. al.
 
Last edited:

Adopado

Well-Known Member
Aug 19, 2019
5,760
4,367
Scotland
So, i've got a 90D as a courtesy car while my 2021 model 3 is being repaired. Never had a Tesla before so I only know the speeds that I get from my 3.

At work we have a piddly 4kw charger. But I know that if I stick my car on there and go out and do a 10 hour shift, it will be full when I get back, regardless. It normally ends up charging a lot quicker than it says it will actually.

I stuck this 90D on today for about 9 hours.....and it went from 30% to 60%

Is that normal for these? I checked that the charge wasn't limited in app or anything. I'm not really enjoying this car (although its better than nothing granted) but if this is the charging speeds i'm gonna get then my god I want mine back asap!
Bigger battery... same rate of charge...
 
  • Informative
Reactions: Billbrown1982

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