For a Model 3+ (being delivered next week), how many miles driven per hour of charge will I get from a wall charger wired into a 60A breaker? I've seen people say 44 and I've seen people say 32. What have you actually seen from your wall charger?
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Exactly how many miles driven per hour of charge?
- Thread starter Wingsy
- Start date
Your 60A is meaning less, since the SR+ will charge at no more than 32A.
Only the LRs will take advantages of the wall chargers for the matter of speed.
Although I am not answering the question, I just wanted to mention that if you're buying the wall unit to charge faster, it is a waste of money. Your mobile connector with the 14-50 adaptor will give you the same speed. However if you want it for other reasons it is a different story of course.
Only the LRs will take advantages of the wall chargers for the matter of speed.
Although I am not answering the question, I just wanted to mention that if you're buying the wall unit to charge faster, it is a waste of money. Your mobile connector with the 14-50 adaptor will give you the same speed. However if you want it for other reasons it is a different story of course.
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willow_hiller
Well-Known Member
SR+? Current wall connectors deliver 32 amps at 240 volts. Multiply those two numbers together and you get a rate of 7,680 watts. The SR+ has an EPA rated from-the-wall efficiency of 250 watts per mile. Divide 7,680 by 250 gives you just over 30 miles of range per hour of charging.
notAnExpert
Member
See the table on this page.
The Model 3 numbers listed there are for LR.
For MR, SR+, and SR, use the 32 amp row of that table because those model variants can't take more than 32 amps.
AlanSubie4Life
Efficiency Obsessed Member
In the end for the SR+ your final number is a bit high but basically correct (your math gives 31rmi/hr). However...
SR+ has a 55kWh battery and a range of 240 rmi, so maybe it is closer to 230Wh/rmi.
Also, the Tesla table appears to be aimed at the RWD versions of the Model 3 only, and appears to assume ~230Wh/rmi (the actual constant for the LR vehicle and the SR+, approximately).
In addition, your math does not account for charging losses.
7680W* 0.9 = 6.91kW (delivered to battery)
6.91kW / 230Wh/rmi = 30rmi/hr
For the AWD, since it gets 310 rmi out of the 75kWh pack (rather than ~325 for the RWD), it is closer to:
6.91kW / 242Wh/rmi = 28.5rmi/hr
Summary: Tesla table is slightly optimistic for the AWD versions of the 3. Just something to be aware of. People sometimes get confused about the extra 10% of energy they have to put in their packs as compared to their rated mile use, when they have a meter on their outlet.
EDIT: And of course rated miles are rarely the same as driven miles! The above is just for rated (displayed) miles.
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Using MPH isn’t exact for charging, it’s just a guide using a number more people can get a handle on. Just like using the same measurement for adding gas in an ICE car.
If you want exact numbers you have to use kilowatts
If you want MPH you have to know what your driving style will give you and work backwards from the kilowatt number.
If you want exact numbers you have to use kilowatts
If you want MPH you have to know what your driving style will give you and work backwards from the kilowatt number.
willow_hiller
Well-Known Member
The EPA rated 250 wh/mi factors in charging losses. It's an average measure of how much you can drive from the electricity measured from the wall. It does seem like an odd thing when you think about it. The EPA wouldn't rate an ICE vehicle's MPG higher if they frequented leaky gas pumps!
The expectation is that gas pumps won't leak. If they all leaked 10%, we'd have a major problem on our hands.
willow_hiller
Well-Known Member
The expectation is that gas pumps won't leak. If they all leaked 10%, we'd have a major problem on our hands.
Maybe this is a question for @Zoomit , but do Tesla vehicles experience more or less charging loss when DC fast charging? I assume most of the loss is in the AC/DC conversion; so the EPA may be understating the efficiency of the cars if you only supercharge.
AlanSubie4Life
Efficiency Obsessed Member
That's true. However, it does not contradict anything I said. Interestingly, I don't know whether it is new, but finally on the EPA fueleconomy.gov the SR Plus exists - it is 250Wh/mi (vs 260Wh/mi for the LR RWD). It did not exist a couple days ago when I checked AFAIK. Interestingly, SR (non plus) is still at 260Wh/mi.
Fuel Economy of 2019 Tesla Model 3
So that lines up pretty well with the 10% charging losses which implies driving efficiency of around 230Wh/rmi (225Wh/rmi). It also suggests that if it really does have a 55kWh battery, the rated range of the SR+ of 240rmi seems a bit pessimistic. Just by a few miles and will be lost in the noise, but I expect the very best reported driving efficiencies from the SR+ just based on the EPA numbers. As one would expect since it does not have quite the road-hugging weight of the other vehicles.
The losses when DC fast charging will certainly be lower, but I have never measured it myself and I don't know how Tesla indicates the energy delivered during Supercharging (since I never do it), so not sure if the efficiency can be directly calculated (probably can, I just don't know).
I would guess the loss is less than 5% in that case. But supercharging is generally so expensive relative to home charging it seems like the EPA numbers would still be the relevant ones to look at.
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Is DC charging have more or less efficient than AC charging? Maybe about the same, possibility less. 50kW DC Fast Charging units are about 92% efficient converting from 3ph 480VAC to 400VDC. That’s about the same as 240V AC charging. Here’s some data on a popular DCFC from INL: https://avt.inl.gov/sites/default/files/pdf/evse/ABBDCFCFactSheetJune2016.pdf
I don’t know how Superchargers compare. Losses go up with increased amperage but the duration that the car’s systems have to operate goes down.
If your question is whether there are fewer losses from Supercharging, I’d guess not. Just like accelerating quickly takes more energy to get up to speed, pumping electrons into the battery faster will take more energy.
The SR+ tested to 247 mi per the EPA documents and was voluntarily lowered to 240 by Tesla.
AlanSubie4Life
Efficiency Obsessed Member
Thanks. Haven’t been tracking these details. That definitely seems to line up with the numbers!
Mo City
Active Member
I drive a little over 100 miles each day and it takes an average of 3 1/2 hours to charge reach night.
AlanSubie4Life
Efficiency Obsessed Member
I think the question that was being asked here is from the DC out of the supercharger, to when it makes it into the battery - what is the efficiency? Presumably the only losses will be the heat generated as charge is pushed into the cells. (There won't be any AC/DC conversion loss in the car.)
As you say, presumably the efficiency of a Supercharger from AC to energy delivered to the battery won't be much different than a home setup (presumably it might typically be a bit worse depending on I^2*R heating losses); it's just dependent on converter efficiencies and these other heating losses.
I have always assumed that Tesla bills for energy delivered to the battery, which provides an inherent benefit to Supercharging as far as cost goes (well, Supercharging is really expensive to begin with, so really more of a discount on Supercharging when comparing to the cost of charging at home - home charging of course will normally win out and has the benefit of not being a huge pain in the rear). However, I have no idea, as I have free Supercharging, and I also don't ever Supercharge.
The losses from a Supercharger should be similar. It’s just a stack of 12 of the chargers that are in the car, grouped together.
OP, the discussion went sort of off in a slightly different direction, but both 44 and 32 are the correct answers to your question, depending on which tesla you are talking about.
I have no idea what tesla you mean when you say "Model 3+" because tesla does not sell that as a model, and it doesnt fit the slang used here either.
You could be talking about a "Model 3 Short Range +" or Model 3 SR+. If so, 32 miles per hour range is the maximum charging speed you will receive on that car, provided you are not using a tesla supercharger.
You also could be talking about a Model 3 Performance, which some here refer to aw a "Model 3P+" or "M3P+" (although the M3 nomenclature is completely wrong). If you mean that car, then you will be able to get 44 Miles per hour charging on a 60amp circuit using a tesla wall connector at home.
I am going to guess that you mean the Model 3 SR+ which is the same assumption someone else made in this thread, but the above is why you are seeing both answers.
AlanSubie4Life
Efficiency Obsessed Member
Sure, as I said above, that is true, but the question was: do you get better cost efficiency? At home, you pay for what you pull from the wall. What does Tesla charge you for (my guess is energy delivered to the battery)?
(And even if they charge for energy delivered to your car charge port (rather than the battery), would that still be better, and if so, how much better?)
The question really (as I understand it) was: how much of the energy delivered to the car charge port makes it into the battery as useful stored energy in the case of DC charging? In the case of AC charging it is ~90%.
(And a related question is what does Tesla charge for when supercharging? 1) AC power 2) Power delivered to car charge port or 3) Energy stored in battery during session?
My guess is 3) (meaning you would not pay for any conversion and battery heating losses) but I have no idea.). Does Tesla charge for energy used to heat your battery when it is cold arriving at a Supercharger? Also I have no idea...
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I don't know what power value Tesla measures to tabulate the Supercharger bill, but we do know what the power reference is as shown on the screen during a Supercharging session. Those kW's are power delivered to the battery and don't include car HVAC. This is hard to determine from a Supercharger, but can be discerned from European CCS stations. Bjorn has a recent video that shows DC Fast Charging his Model 3. The DCFC unit shows it's power output and he compares it to the in-car displayed value.
HVAC Off
DCFC: 120.3-120.7 kW
Car: 120 kW
HVAC On
DCFC: 127.7-124 kW
Car: 120 kW
So if Tesla charges based on the power indicated on the screen, that would be power provided to the battery. That doesn't include internal battery charging losses, nor HVAC or presumably other car accessories.
The answer to this question is challenging because it requires knowing the battery usable capacity. The Tesla EPA submissions have two examples of LR battery capacity measurements: 78.269 and 79.218 kWh. We can average those and assume 78.74 kWh. u/Wugz has some accurate charging session data posted online. I looked at a 9 min period of steady 145 kW charging and calculated a 2.5% charging loss.
Specifically, this was 144.7kW of power going into the battery but the power stored was 141.1 kW over 9.16 minutes gaining 27.4% SOC.
For reference, if we assume the usable capacity is only 75 kWh, the charging loss recalculates to 7.1%.
Also, I've used between 5 and 8% for my models of other OEMs batteries. Those were at much lower power levels and have different thermal management systems so they are hard to compare.
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