First charge!!

[Rocky_H]

Read the original post that I quoted. It had nothing to do with some 2nd level calculation.

Yes it did.

It had everything to do with someone thinking that the rate of charge was tied to the trim level, which it is not.

As I have been trying to explain to you, the fill rate in terms of energy per second will be the same. The filling rate in terms of distance per second will be different, and that was what the person was specifically referring to.

Obviously the trim level can affect the efficiency of using said energy in the battery pack, but when charging the vehicle, the trim level or wheel size means absolutely squat.

Then feel free to give your explanation of why things like the Model S 85 had a different recharging rate in miles per hour than the P85D, which both used exactly the same battery.

 

[Rocky_H]

I am in the know. I'd lay 2:1 odds that the battery pack in the OP's car has my fingerprints around the penthouse somewhere. I'm a process engineer for Tesla in the Gigafactory. I touch anywhere between 50-100 of these packs a day...

And that's great. I'm certain you do know tons more than I do about most aspects about how those battery packs are made and function. But in this particular area about how the efficiency calculations display in the use and charging, you just aren't getting it correct, or maybe aren't communicating it well.

 

[GigaGrunt]

Tesla estimates 44 miles/hour with the HPWC @ 48A, so I'd say you're pretty close. Perhaps the 2-mile delta is because you have a Performance, which is a little less efficient than the RWD version and gets fewer miles per charge.

Wall Connector

See above. He stated the difference in charge rate could be due to the Performance model, compared to a RWD. It will charge the same. No. Matter. What. it may net out to a few less miles when driving, but charge rate is not affected by the trim or wheel size.

Yes it did.

As I have been trying to explain to you, the fill rate in terms of energy per second will be the same. The filling rate in terms of distance per second will be different, and that was what the person was specifically referring to.

Then feel free to give your explanation of why things like the Model S 85 had a different recharging rate in miles per hour than the P85D, which both used exactly the same battery.

Depending on the installed options, but I recall the P85D had dual chargers as part of the P package, where as the base 85 only had a single charger. I wasn't employed here then. But the Model 3 has the same charger in all cars currently produced. With the same battery pack. And the trim package or wheel size does not change the charge rate. Period.

 

[GigaGrunt]

And that's great. I'm certain you do know tons more than I do about most aspects about how those battery packs are made and function. But in this particular area about how the efficiency calculations display in the use and charging, you just aren't getting it correct, or maybe aren't communicating it well.

It has nothing to do with efficiency calculations and how they display in the use and charging on displays. The person theorized the trim level may affect charging rate. And I'm here to tell you it doesn't.

 

[Eno Deb]

It has nothing to do with efficiency calculations and how they display in the use and charging on displays. The person theorized the trim level may affect charging rate. And I'm here to tell you it doesn't.

You are wrong. Given the same charging power, a more efficient vehicle gains more range per unit time than a less efficient vehicle. That's why a RWD Model 3 will charge slightly more miles/hour than the AWD version from the same power source.

 

[narayan]

The battery resistance increases as the it takes on charge. Eventually it's "full" and can't eat any more electrons. Think of it like filling a big tall water tank from the bottom with a garden hose. Eventually the pressure trying to escape the tank will be equal to the pressure of the water going in and it won't take anymore water.

Not quite. It's really the voltage difference that determines charging current. In the first order, the battery internal resistance can be considered constant (an actively cooled battery). Let's say it has some value R. Let's also assume that you are using a supercharger whose internal resistance (impedance) is close to 0. If Vc is the charger voltage and Vb(t) is the battery voltage, then the maximum current the charger can source into the battery is (Vc-Vb(t))/R. At the start of charging, the Vb(0) is at minimum, you get maximum charging current. I(0) = (Vc - Vb(0)/R. As Vb increases, I decreases. Towards the end, it probably drops to a low enough value (for fully charging a battery), that the charger senses this current and turns itself off. In reality, the resistance, R, of the battery does increase as it heats up, and this will also decrease the current further, but I believe this is a second order effect in the Tesla. Not so much for cars like the Leaf whose battery pack has no temperature management.

 

[GigaGrunt]

You are wrong. Given the same charging power, a more efficient vehicle gains more range per unit time than a less efficient vehicle. That's why a RWD Model 3 will charge slightly more miles/hour than the AWD version from the same power source.

I'm sorry but you're wrong. The efficiency in which this vehicles uses the energy from said pack has nothing to do with how it charges said pack. If you're seeing any difference in the charging rate of a RWD vs AWD, I assure you it has nothing to do with the efficiency of the vehicle.

I watch these packs move down the line all day. A RWD and an AWD pack have the same internals, the same cells, with only additional circuitry for the FDU and add't cabling for the FDU. Nothing else is different.

 

[Rocky_H]

See above. He stated the difference in charge rate could be due to the Performance model, compared to a RWD. It will charge the same. No. Matter. What. it may net out to a few less miles when driving, but charge rate is not affected by the trim or wheel size.

Oh my gosh. Dude! You really need to go back above and re-read the example I gave to you about filling the Ford F-250 and the Ford Fiesta. From the same gas station hose, they will fill at the SAME rate in terms of gallons of fuel per time. But they will fill at very DIFFERENT rates in terms of miles per time. Do you still not understand that? You seem immovably stuck on the energy filling rate.

There are two different measures, and you refuse to understand this. You would have been correct if the person had been referring to kW charging rate or kWh per second, or something like that, because yes, the rate of energy transfer does not depend on the trim or efficiency. But since the person was talking about the miles per hour recharging rate, that is directly impacted by trim, efficiency, etc.

I am really trying to be patient with you, but your refusal to learn is making this much more difficult than it needs to be.

 

[GigaGrunt]

It's funny that in the face of evidence, people will stand by what they think they know, no matter what.

Keep holding on to your 'hokey 2nd level calculation'....

 

[Rocky_H]

@GigaGrunt Let's see if I can try this again, since you seem to just want to disagree rather than understand. Let's say you were filling two versions of Model 3. You gave them the same charging time from the same source. They both got exactly 10 kilowatt hours of energy. That's the same filling rate, right? You've been saying they have the same filling rate because they have the same identical battery. That would be correct, because they got the same amount of energy. But on the displays, one version says that it got 40 miles added. The other might say it got 42 miles added. Now why would that be?

It's funny that in the face of evidence, people will stand by what they think they know, no matter what.

Yes, I'm finding that interesting.

 

[Eno Deb]

I'm sorry but you're wrong. The efficiency in which this vehicles uses the energy from said pack has nothing to do with how it charges said pack. If you're seeing any difference in the charging rate of a RWD vs AWD, I assure you it has nothing to do with the efficiency of the vehicle.

Assume the battery has a low state of charge and can charge at the full 240V/48A, i.e. 11.52kW. One hour of charge will thus put 11.52kWh into the battery. Assuming the RWD uses say, 230Wh/mile and the AWD 250Wh/mile, during the one hour the RWD will gain a range of 11.52/.23=~50 miles, and the AWD 11.52/.25=~46 miles. Thus, the RWD charged at 50 miles/hour and the AWD at 46 miles/hour from the same power source.

 

[SSedan]

GigaGrunt.
Look at what I said. I said that if the same car were offered with trim packages that included different this was a hypothetical situation TIRES THAT HAD DIFFERENT EFFICIENCY RATINGS, maybe one low rolling resistance the other full sticky performance, that would result in the cars being programmed with a different standard energy per mile ratings. That would result in different mileage added at the same amperage setting. My point was pack size has NOTHING to do with charging rate expressed in miles, programmed standard vehicle energy use is all that dictates that.

Lets take this further the Model S and X have the same batteries, chargers and motors right, I thought so but could be wrong? For a given amount of energy input though they do not get the same mileage added, that is because the energy use per mile is different between the two vehicles.

 

[StellarRat]

You guys are clearly talking about two different things. One person is talking about range gained over charge time, while the other is talking a power stored over charge time. #1 is true if both vehicles have identical charging system and battery packs then yes, the more efficient vehicle will get more driving range for time of charge. It stands to reason a car that can get 500 miles on full charge with the same battery as one that can only get 250 miles is going gain more range per charge time as it is twice as efficient in power consumption per mile. But, as far as actual power dumped into the batteries they are exactly the same if the batteries and charging system are identical. Looking from the power use efficiency perspective then I'd have to say the M3P with fat tires is least efficient while the RWD is most efficient.

 

[Rocky_H]

You guys are clearly talking about two different things. One person is talking about range gained over charge time, while the other is talking a power stored over charge time. #1 is true if both vehicles have identical charging system and battery packs then yes, the more efficient vehicle will get more driving range for time of charge. It stands to reason a car that can get 500 miles on full charge with the same battery as one that can only get 250 miles is going gain more range per charge time as it is twice as efficient in power consumption per mile. But, as far as actual power dumped into the batteries they are exactly the same if the batteries and charging system are identical. Looking from the power use efficiency perspective then I'd have to say the M3P with fat tires is least efficient while the RWD is most efficient.

Yes, that is what I've been trying to explain this whole time. Let's not misuse the terms, though. It's energy going in, not power. Power is the rate of energy transfer.

 

[Eno Deb]

You guys are clearly talking about two different things. One person is talking about range gained over charge time, while the other is talking a power stored over charge time.

Yes, but the OP's question and subsequent replies were specifically about miles/hour charged, which depend in part on the efficiency of the vehicle. Anyway, the OP seems to have left the building, so perhaps it's time to let the thread die.

 

[StellarRat]

Yes, that is what I've been trying to explain this whole time. Let's not misuse the terms, though. It's energy going in, not power. Power is the rate of energy transfer.

Fine, fine, STORED power. How's that? Let's give this one a rest now. I think there was just a miscommunication here.

 

[BestHand]

...it may net out to a few less miles when driving, but charge rate is not affected by the trim or wheel size.

Here you actually agree that for the same value of energy less efficient car drives less miles. So, assuming that car computer shows speed of the charge in miles added to its displayed range it is obvious that for the same capacity batteries it will show higher speed for more effective car. We do not define rate of charge as how much energy we put into the battery in time cause it is not what we interested to know, we want to know how many mile we adding to our range in time.