I think the Model 3 will only be available in 2 battery configs, an entry level and an upgraded level. Initially that means 75KWH as Elon stated was the largest they could fit at this time, and some smaller size. The reason is that this car is intentionally being manufactured with as few variants as possible in order to keep down complexity and cost. Upgraded battery cars will be produced and shipped first, as Elon stated. Also, RWD only at this time. So, I'm good with that. I'm looking to order a RWD car with upgraded battery.
IdaX
Member
Yeah, that number could be in the ballpark. Would be more like 260 Wh/mi without the weight difference, but some additional modest improvement could come from the lower weight.
JeffK
Well-Known Member
IdaX
Member
Well, all things being equal, looks that way. I don't know much about the Bolt, but reading on Wikipedia it looks like the Bolt gets 208 Wh/mi, and with a horrendous 0.3 Cd too. I couldn't say why Tesla is less efficient: more losses in the motors? Higher losses maintaining battery temperature? Harder to compare across manufacturers like that.
Swampgator
Active Member
IdaX,
You don't understand the physics properly. Rolling resistance increases with vehicle weight. This therefor increases the amount of energy that must be expended to move that weight even while not accelerating.
You don't understand the physics properly. Rolling resistance increases with vehicle weight. This therefor increases the amount of energy that must be expended to move that weight even while not accelerating.
IdaX
Member
Uh-huh. Rolling resistance is just not the primary loss mechanism at 60mph: drag is. The difference in friction in the axles isn't driving the losses. Take a look at this graph (which is actually for the Roadster but shouldn't be too far off for the Model 3):
Drag losses are a little less than triple the rolling resistance.
Swampgator
Active Member
That dark blue line (RR) moves up as weight increases, independent of drag.
That was exactly my point. The Roadster weighed about 1000 pounds less than the Model 3 will weigh.
You had commented "So weight won't affect highway mileage unless you're going uphill or downhill." and this is incorrect. 1000 pounds may move that line up to 80 on your graph, closer to the impact of drag on range and possibly exceeding the drivetrain impact. Yes, all other things equal drag is the main factor as speed increases, but weight is an important factor still.
That was exactly my point. The Roadster weighed about 1000 pounds less than the Model 3 will weigh.
You had commented "So weight won't affect highway mileage unless you're going uphill or downhill." and this is incorrect. 1000 pounds may move that line up to 80 on your graph, closer to the impact of drag on range and possibly exceeding the drivetrain impact. Yes, all other things equal drag is the main factor as speed increases, but weight is an important factor still.
We can calculate what the Model 3 should get in terms of Wh/mi, if you don't mind my dropping some science on your ass. The units Wh/mi, if you simplify them, come out as just a force in Newtons. And at speed, the force required to keep a Tesla moving at that speed is proportional to v^2 as it's mostly drag. F_drag goes as Cd*A*v^2, where Cd is the drag coefficient, v the velocity, and A the cross-sectional area. Let's assume that the Model 3 will get the same Cd as an S: Cd=0.21. Then its force, or Wh/mi, will scale with the S's as their relative cross-sectional areas.
Width = 1.885m and height = 1.435m for the Model 3 according to Wikipedia. Leads to a cross-sectional area of 2.705 m^2 if it were square. I realize that it's not, but so long as it has the same profile as the S then the difference from square will come out in the wash.
For the S, the width is 1.964m and the height 1.435m. So area is 2.818 m^2.
So by that calculation, then, the Model 3 won't get all THAT much better Wh/mi than an S: it would do just 4% better in fact. Assuming highway driving. If a Model S75 gets 259 miles of range, then, I would expect that a 3-75 would get something like 270 miles of range. Could get a smidge more if it's lighter (but maybe it won't be with all that steel instead of aluminum). Not the magic 300, but not too shabby.
I'm pretty sure the Model S has a Cd of .24 not .21. If I accept the rest of your assumptions and plug the correct Cd for the S in, I come up with a ~ 16% difference which would give the Model 3 75D a range of 300.44 miles.
As been pointed out by others, weight does make at least some difference, so the Model 3 75D should be well over 300 miles in range.
Of course I have my heart set on ludicrous, so no 300 mile range for me.
ModelNforNerd
Active Member
So I'm gonna BLOW YOUR MIND here, and counter you with this:
Margin.
Which trim level does Tesla stand the most to gain margin-wise on, to replenish the capital outlay they have for start-up costs?
Hint: It's got a P, a 75, a D, and maybe even an L somewhere in it.
If we don't see it right away, it's not because of some "performance gap", it's because it's not ready.
They WANT it to be out there and recouping cash for them.
@IdaX, check out my range calculations here. I think you will find that interesting. I should point out that I wrote those in December 2016, long before Elon tweeted about the 75 kWh. Since then I have fine-tuned the calculations. The new version is here. I'm now expecting 297 mi EPA for the Model 3 75D.
IdaX
Member
Nice! I hadn't appreciated that the M3 Cd would be lower than that of the MS (not sure why I thought the MS was 0.21; your source definitely has some authority to it!). M3 isn't as long as MS, so that should help it somewhat to get the lower Cd. Your spreadsheet definitely tells the tale, as you account for all factors!
Tam
Well-Known Member
Swampgator
Active Member
I'm gloating a little bit, but I was called out by sooo many for thinking the M3 75 would exceed 300 miles and weigh less that 4000#
From my post in April 2017:
Tesla will NOT use the same motor as in the S and X.
Why would they? The Model 3 will be 20% lighter than the S, so a smaller motor will give plenty of go power along with the required efficiency.
There is also a report of a third party vendor stating they are making permanent magnet motors for the M3. SO if true this will be a major departure for Tesla. But one thing for sure is that Tesla is not afraid to challenge the current orthodoxy...even when it is their own.
Some think they will be using a new, hybrid type motor than is more efficient than a given induction or PM motor of the same size.
This is the fun stuff we get to see at the next reveal.
From my post in April 2017:
Tesla will NOT use the same motor as in the S and X.
Why would they? The Model 3 will be 20% lighter than the S, so a smaller motor will give plenty of go power along with the required efficiency.
There is also a report of a third party vendor stating they are making permanent magnet motors for the M3. SO if true this will be a major departure for Tesla. But one thing for sure is that Tesla is not afraid to challenge the current orthodoxy...even when it is their own.
Some think they will be using a new, hybrid type motor than is more efficient than a given induction or PM motor of the same size.
This is the fun stuff we get to see at the next reveal.
JeffK
Well-Known Member
I think many of us said something similar. Especially since JB's comments were that it was an entirely new motor design for Tesla.I'm gloating a little bit, but I was called out by sooo many for thinking the M3 75 would exceed 300 miles and weigh less that 4000#
From my post in April 2017:
Tesla will NOT use the same motor as in the S and X.
Why would they? The Model 3 will be 20% lighter than the S, so a smaller motor will give plenty of go power along with the required efficiency.
There is also a report of a third party vendor stating they are making permanent magnet motors for the M3. SO if true this will be a major departure for Tesla. But one thing for sure is that Tesla is not afraid to challenge the current orthodoxy...even when it is their own.
Some think they will be using a new, hybrid type motor than is more efficient than a given induction or PM motor of the same size.
This is the fun stuff we get to see at the next reveal.
What's going to be interesting is that it's a 258 HP motor. Note the Model S 85D at 0-60 in 4.2 seconds had two 259 HP motors. I wonder what's in store for Model 3 AWD.
ModelNforNerd
Active Member
Tam
Well-Known Member
More clarification from Elon Musk:
standard: Just over 50 kWh
Long range: about 75 kWh
Tesla Model 3 battery packs have capacities of ~50 kWh and ~75 kWh, says Elon Musk
standard: Just over 50 kWh
Long range: about 75 kWh
Tesla Model 3 battery packs have capacities of ~50 kWh and ~75 kWh, says Elon Musk
Fusion
Member
Pkmmte
Le meow
If that's the case, then this thread's title is technically correct...
Found this on reddit... image is not mine.
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