ℬête Noire
Active Member
Same motor, lower peak current passed through it. It does make sense. Well I'm not sure those exact numbers but as a concept it does.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Let's discuss Dual Motor range
- Thread starter ModelNforNerd
- Start date
Knightshade
Well-Known Member
So wouldn't that reinforce the idea that the P speed difference is entirely a software difference? (they're essentially making the AWD slower than the P by reducing the current sent to the same physical parts)
ℬête Noire
Active Member
For all effective purposes it is entirely how much current Tesla is willing to pass through the motors & power electronics, putting extra wear on the drivetrain and stress on the frame, and still honor the full warranty.
Tesla is doing an extra level of testing to make sure they put into the P the best candidates for not melting down and/or flying apart when this is done.But yes, the maximum current flow is entirely dictated by software controlling semiconductor gating, as it is in all EVs.
Last edited:
Knightshade
Well-Known Member
It's entirely how much current Tesla is willing to pass through the motors & power electronics, putting extra wear on the drivetrain and stress on the frame, and still honor the full warranty.
But yes, the maximum current flow is entirely dictated by software controlling semiconductor gating, as it is in all EVs.
Well, my expectation had been they were getting P>AWD performance by getting significantly more power out of the FRONT motor in the P- not that they were pulling back on the power from the rear.
We know that Tesla is already ok putting 800 through the rear motor in every RWD model 3 they sell, so clearly if they're cutting the same motor back to 500 on the AWD to make it not as fast as the P, that's just marketing, and a later uncork for AWD models would be simpler and more likely than the other scenario (where they're limiting current to the non-binned-winner front motor for warranty reasons)
I'd still like to know where the 500/800 claim comes from though and if it's just "something a dude on reddit said" or has a real source.
For all effective purposes it is entirely how much current Tesla is willing to pass through the motors & power electronics, putting extra wear on the drivetrain and stress on the frame, and still honor the full warranty.
But yes, the maximum current flow is entirely dictated by software controlling semiconductor gating, as it is in all EVs.
The same argument can be made even with ICE cars. A lot of ICE engines are actually detuned at the ECU level but have varying power levels depending on what car it's in.
diamond.g
Active Member
Below quote block cribbed from Electrek, which came from reddit which came from @Ingineer
I complied the following information from Ingineerix's posts on Reddit and Youtube:
www DOT youtube DOT com/playlist?list=PLwPiVR1Wtwc1cxO0vlvx5rDnHShUuHvXS
www DOT reddit DOT com/r/teslamotors/comments/7y3t8v/model_3_teardown_videos_youtube/
www DOT reddit DOT com/r/teslamotors/comments/7zyoas/model_3_factory_mode_battery_pack_info_revealed/
Model 3 LR:
Wiring:
"Mostly CAN with a touch of Ethernet (including BroadR-Reach single pair)."
Wiring reduced by having 3 body controllers instead of 1
*No fuses* in Model 3. All solid state virtual fuses. You don't actualy blow anything, you just trigger a software shutoff of the power until you reset the "fuse".
Display:
"Connected by a 2 twisted pair system called FPD link III. There is a 4-pin Fakra HSD connector on the ICE (computer) module behind the glovebox area that can be easily accessed"
Suspension:
Top suspension arm FRP, curiously enough.
Massive front stabilizer
MCU/ECU (computers, incl. autopilot):
Liquid cooled by the main glycol loop
Seat heaters:
"Rear seats do indeed have heaters and they are connected. Just no way in the GUI as yet to enable them."
Drive unit:
"The drive unit contains the Inverter, Switched-Reluctance motor, a gear-reduction, and a differential to split the torque between the 2 wheels."
"The RWD has a higher capacity inverter than the AWD. (800A vs 500A) I don't know if there will be a "P" version yet, but maybe that one would retain the 800A in the rear and add a 500A in front."
Front motor:
There's a giant hollow already just waiting for it. "Cavernous space. You could put a small child in here." Note for if you need a smuggling compartment...
Pack:
" I can tell you the voltage ranges haven't changed too much. BMS considers 100% SoC at 4.2v per cell but the bottom changed slightly; it's now 2.85v/cell for 0% SoC, whereas on S/X it was 2.5v/cell. Note that Tesla advises owners not to charge above 90% daily unless really needed, so that puts the top at around 4.1v/cell. There is also a bottom reserve of 3.5kWh that you can't touch."
4426 2170s, 96S46P arrangement, 4x modules
76kWh actual, 74kWh nominal. Possibly only 72.5 kWh usable due to the 3.5kWh "bottom reserve".
Max charge 192A**, max discharge 1200A (ED: this appears to be max regen, as it's in the same column as regen (equates to 47-78kW). Max discharge equates to 294-482kW / 392-646 max theoretical HP from the pack)
Min bus voltage 245V, max bus voltage 402V
Max regen 46,9kW, max discharge 370kW
Cooling:
Mounted on sizeable rubber gaskets and with a lot of acoustic foam, to keep it quiet.
Weights added to the cooling fan to ensure that it's properly balanced.
12V battery:
45 Ah. Not sealed.
Heat exchanger:
"It's a plate stack type on top of the drive unit. Looks similar to the one I showed in the 1st video where the glycol is chilled by the A/C refrigerant. "
"Yes, and not only that, but if it is super cold and they actually need to add heat (the motor/inverter is super efficient, so not much waste available), they purposely run the inverter in an inefficient mode to generate excessive waste heat to heat the pack. S/X had a s***ty electric battery heater in the glycol loop and these seem to be very unreliable. So on 3 they basically did it with software!"
Build quality and engineering:
"I've taken apart hundreds of cars so far, and I find the 3 to be well put together and a lot of thoughtful engineering throughout. Particularly impressed by the high levels of integration as compared to S/X. Also going to a electric pump and filter on the DU means they want it to last a long time. Really, the only maintenance most owners will need to perform is adding windshield washer fluid and replacing tires. Maybe a 12v battery every 5 years. Brake pads should do 100k unless you do a lot of aggressive stops."
"I think you must be referring to Sandy Munro. He had a lot to say about the fit/finish and went on and on about how the first responders can't get to the cut loop. First off, none of the fit/finish issues exist on recent the cars I've investigated, and secondly, Sandy's focus on the cut loop is silly. In any accident that would need first responders to cut into the car, the HV system has already been totally disabled by the RCM (Airbag Computer). Anything that matters seems to be really good. I welcome more objective analysis though!"
General safety:
"The RCM (Airbag ECU) blows the HV pyrotechnic disconnect in the HV pack as soon as there is an accident. Easy to safe the HV system by unplugging one low-voltage connector."
"The HV system is totally isolated from the chassis, and if the BMS detects that the isolation has been compromised, (due to a short from chassis to any part of the HV system) it will open the contactors."
"The fire vents relieve any pressure inside the hermetic pack enclosure, and if there are any hot gases, the deflectors redirect them to a safe place. There is a cabin filter, but it's inside, so a post filter, not a pre-filter like the S/X have."
"There is a lot of redundancy in critical systems. I've seen it in the BMS, Brakes, Power steering Rack, CAN buses, and Power distribution (no fuses). I haven't had the drive unit apart yet, but I expect it to have some redundancy, or at least built with fault tolerance in mind."
Power steering = 2 separate controllers; one can fail and you still have power steering.
Crash energy absorption structure is unboltable. If the car is in a crash, you can remove it and install a new one.
Automatic water vent if the pack somehow gets flooded.
From another user, about Ingineerix who took the car apart, in comparison to a person who posted a different teardown:
"I don't know what qualified that person to assess the quality of engineering, but I know Ingineerix personally and have never met anyone with a higher level of engineering skill and knowledge."
I don't understand why the REAR would be limited to 500, instead of the front. When accelerating, the car shifts its weight onto the rear wheels, give you more traction. That is where you want most of your power. If they limited the front to 500, then it would make sense instead. Or are you saying the RWD is 800, the AWD is 500 in both, and the P is 800 rear, 500 front?
ℬête Noire
Active Member
I highly doubt drastically changing the front-back power split like that makes engineering sense.
First thing is you assume something like the Model S power split, or on even rougher 1/3 front, 2/3 rear approximation. Then you extrapolate the Amp needed (as per what I did further up).
Incidentally that does suggest that the specific number 500A is too low, more like capping current to the back to 660A makes sense. Not sure what Mr. Reddit was thinking, allegedly, maybe something I'm missing?
Last edited:
Spudford
Member
Now, I'm no engineer, and I know jack squat about electricity and physics, but I know some statistics. My impression of modern manufacturing is that tolerances are very closely tracked, and when there is a statistically significant variation identified on some parameter during production, it constitutes a quality problem that is hunted down and fixed. (Or maybe compensated for.)
I know that when ICE race car engines are rebuilt, they will sort through mountains of pistons to find the ones that weigh the least, so maybe I'm off base here. But I'm guessing that the performance advantage gained from cherry-picking electrical/electronic components won't be much.
If I sort through 10,000 shoelaces to find the two lightest-weight ones, and put them on Usain Bolt's shoes, I think it would probably make less of a difference in his performance than telling him his shoelaces were lighter.
I know that when ICE race car engines are rebuilt, they will sort through mountains of pistons to find the ones that weigh the least, so maybe I'm off base here. But I'm guessing that the performance advantage gained from cherry-picking electrical/electronic components won't be much.
If I sort through 10,000 shoelaces to find the two lightest-weight ones, and put them on Usain Bolt's shoes, I think it would probably make less of a difference in his performance than telling him his shoelaces were lighter.
Knightshade
Well-Known Member
Right. That's exactly why the only difference between the AWD and base P appears to be software..
Which makes it highly likely you'll see some uncorking later- either a "free" small bump as the Model S got when competition requires it, or a large paid one when it makes economic sense for Tesla to offer it.
Knightshade
Well-Known Member
well that's why I was asking- we know the 800a # on RWD is a "real" number from an actual teardown of a car.
People are quoting the 500 number as if it has some basis in fact- but so far I can't find any (and AFAIK nobody has an AWD to check- so unless someone found something in software with early AWD code it appears to be someone just randomly guessing)
No. Every Tesla product has someone saying something like this early and then manufacturing disappointment for customers that let this seed grow/fester. Please stop.
ℬête Noire
Active Member
That's a definite possibility, depending on what kind of mortality rates they are seeing in actual use. Although we should expect any "uncork" to come well short of the Performance, I'd think?
ℬête Noire
Active Member
It's unclear if there is going to be much C-rate ceiling in the battery to uncork the Performance. I assume you're referring to some sort of Ludicrous mode? I guess we'll see when the Performance comes out how much it appears to have left to open up.
Knightshade
Well-Known Member
I think you could see a couple things-
A) They offer an additional cost L upgrade for the P that bumps that and then like the S did with uncorking, everything else gets significantly faster for free-probably as competition shows up... Same gap between them but moves everything up a bit compared to other cars
B) They decide the AWD motor tolerances really are basically identical to the ones making the cut for the P, and they decide to offer AWD owners a P unlock that essentially converts it to the same as a base P... it'd have to be same (or probably a little more) than the current 11k price to not upset previous P buyers or hurt future P sales- but I bet they'd still get some decent takers for what essentially costs Tesla nothing versus some P upgrades they offered for the S that actually required HW changes... (and I suppose they could then offer the additional paid L upgrade too for those cars)
ℬête Noire
Active Member
The rub with this is that it relies on the premise that maximum battery current found via the factory mode hack, 1200A, isn't what the battery is capable of. Napkin math suggests they'll need basically all of that 1200A to drop from the RWD's 4.8sec to the P's 3.5sec (rolling start to rolling start). We'll see I guess.
JeffK
Well-Known Member
So this was posted to reddit. 116 MPGe for 310 mi range.
Damn I want that white interiorSo this was posted to reddit. 116 MPGe for 310 mi range.
Similar threads
- Locked
- Marketplace listing
- Marketplace listing