jebinc
Well-Known Member
They can add more batteries to a "For Fee" Option to the base DM AWD, IMHO. Say 400 mile range for an extra $1500 and 500 mile range pack for $3000.
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Thanks for your comments. Your push back stimulates thinking so I appreciate that. I have no inside knowledge. This is my thinking.
Now you are talking. So if I add a part I want to remove a part or better yet, 2 parts or 3 parts. This is the philosophy EM has used to engineer this new dual motor drive unit.
Getting rid of the differential removes a handful of mechanical parts in a critical functional path. Adding a motor adds a handful of parts and minimal wiring in a non-critical path. The second motor is not critical only the first motor (agreed, this could be debated).
The cost of the Model 3 motor according to Sandy Munro is less then $1000 and has a reduction gear and a couple bearings (I am speculating). The motor is manufactured precisely but has few moving parts.
Once I have thrown away the differential, I can throw away the stability control mechanism that involves frictional breaking as a substitute for real traction management. Now I have real traction management with the 2nd motor and SW. What is possible with SW and real traction is not fully explored yet. A lot will be learned with the Model S tri-motor. Some of that learning has already started on the Nürburgring.
There is a lot we don't know. Will there be a second inverter or a shared inverter or some new improved approach. Will the super bottle be simplified because of the new thermal management opportunities. The new dual motor drive unit will take some time to perfect but with volume production it will happen.
In the end, just as there is a single part number for the rear drive unit there will be a single part number for the dual motor drive unit. The part count will be about the same (my guess) but the feature set will be improved (towing maybe).
We seem to be of different minds about this and that is ok.
There is no question about if it critical or not, it is. For example, if you want the car to drive straight... (At least in a RWD version, I suppose in an AWD vehicle you could disable both rear motors if one of them fails.) Or if a gear breaks and jams, it is hard to drive your vehicle with one wheel locked up... Or if there is a HV wiring fault, etc.
I assume each motor will have it's own oil pump, filter, heat exchanger, resolver, temperature sensors, etc. So it is more than a handful of parts.
It won't be a shared inverter, that doesn't really work if you want independent control of the motors... As far as the SuperBottle if anything it would be more complicated as it has additional items to cool. With likely a larger potential heat load.
Probably not. They will probably have a separate left and right drive unit like they have done in the Tesla Semi.
As far as traction control they have been doing that with four rear motors on the Semi already and think they can greatly reduce the risk of jack knifing because of it. So I suspect that Tesla has a very good handle on what is possible.
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JRP3
Hyperactive Member
An electric motor is a much more complex and costly item to build than a differential.
No you can't. You still want to have all that available even if a motor, inverter, contactor, fuse, etc., fail under motion.
To be blunt I think the issue is there is a lot that you don't know. Motors cannot share the same inverter and still be operated independently. Frankly I doubt PMSRM's can be operated with the same inverter even in sync.
I don't think it will be at all like the semi but it will benefit from all they have learned in the semi. I think it will be a single qualified tested drive unit to be field replaced.
I agree that the semi development experience has delivered a lot of traction management experience.
Show me a differential that is not encased in the traditional pumpkin enclosure and I may consider thinking about possibly agreeing with the diffy-vs-additional drive unit. A pumpkin is a hated feature in the Audie-book: lowers true clearance by a lot and it induces very significant aerodynamic losses.
Are you joking? If an extra 200 miles only cost $3000 then we'd all be driving 500 mile cars right now! The estimates I've seen are that the 500 mile pack is an extra 100-120 kWh on top of the 300-mile pack, and that Tesla would be doing well to build them at $100/kWh -- in other words the cost to them is at least $10,000, so the cost to you would have to be like $15K for that upgrade. I think throwing the extra motor in is probably cheap compared to the batteries, and makes the whole package look better vs. advertising how expensive battery packs are.
JRP3
Hyperactive Member
Not sure I understand, every transaxle has a differential in it, including Tesla's, and those aren't traditional pumpkin enclosures.
jebinc
Well-Known Member
No argument. No one knows what battery costs will be in 2022+. If it's like 4K TVs, that started at $10000 a copy and quickly dropped to under $1000, pack prices in 2022 (and beyond) could be a lot less costly then they are today. I suppose Tesla is counting on that too, since they are offering the base model at $39,999.
You mean like the differential that is contained in every Tesla drive unit?
For example here is the differential in a Bolt EV drive unit:
Just that little four gear set in the middle of the final drive gear. (I couldn't quickly find a tear down of the Model 3 motor.)
RFernatt
Solar/EV Owner/Enthusiast
Saw this McLaren I hadn't seen before today and immediately thought the side profile shape reminded me of the CT.
jeewee3000
Active Member
JRP3
Hyperactive Member
Don TLR
Active Member
Get your Cybertruck Goodies while waiting for your truck to come in, posted last night
https://shop.tesla.com/category/apparel/men
https://shop.tesla.com/category/apparel/men
JRP3
Hyperactive Member
New here been stalking the thread for a while lots of great information so thank you guys.
On to the CT they mentioned in the video the wheels may be different in production but lately I've been thinking about them. Maybe the design is for drag but If CT has air suspension what is the likelyhood that it also has self inflated tires? Would make some sense considering CT is so called bulletproof and the whole tesla glass thing. This is actually pretty common with Semis wondering if maybe it has trickled down into the CT so the wheels are actually designed that way to cover up the air lines that connect to the hub and valve to air them up.
MOD EDIT: No responses, please. Moving this to “CTruck” thread once I awaken.
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