What am I missing?

[Zooman001]

I feel like I am missing something, all three models of the CT are advertised as having a 3500lb payload. But shouldn’t the tri motor with the 500 mile range be less. The extra weight of the motors plus the much bigger battery pack should subtract from the GVWR and equal a smaller payload.

Also if you can make the tri motor go 500 miles why wouldn’t that battery pack be put in the dual and single motor and have an even better range?

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[Jhodgesatmb]

That is what Elon Musk announced in 2019. If you can get him to talk about payload, etc., we have a long list of questions we would love for you to ask him.

 

[Crissa]

You have to be able to move and stop a payload to carry it as well.

The battery will be less than a thousand pounds for a whole battery pack (probably around 500? This is a wild guess) and the additional motor weighs like seventy pounds. So that's a difference of like, two or three passengers.

This difference would matter to a small car, but not to a truck.

-Crissa

 

[Zooman001]

You have to be able to move and stop a payload to carry it as well.

The battery will be less than a thousand pounds for a whole battery pack (probably around 500? This is a wild guess) and the additional motor weighs like seventy pounds. So that's a difference of like, two or three passengers.

This difference would matter to a small car, but not to a truck.

-Crissa

Every pound matters for me, I tow big heavy trailers

 

[Crissa]

Every pound matters for me, I tow big heavy trailers

What's in your truck won't change your towing capacity appreciably, beyond model, because of those battery packs being down low balanced weight.

Just get the tri motor.

-Crissa

 

[Zooman001]

What's in your truck won't change your towing capacity appreciably, beyond model, because of those battery packs being down low balanced weight.

Just get the tri motor.

-Crissa

Actually towing capacity is irrelevant in most cases, payload is almost always the limiting factor in what you can tow

 

[carpedatum]

It wouldn't be a big surprise, I suppose, for these numbers to become a bit different/more precise as the detailed design effort progresses, but it is probably also helpful to remember from Battery Day that Tesla intends to diversify its approach to battery cathode make-up as a function of vehicle demands. The higher capacity batteries may not just be larger/heavier. It is possible, just by using more nickel in the cathode (at greater expense) to produce a higher-capacity pack that doesn't weigh a lot more than a lower capacity one.

While Tesla implied they would go with "High Nickel" packs for Cybertruck and Semi, I don't think that takes using cheaper iron-based or nickel+manganese cathodes off the table for cheaper, lower-range versions of CT. These might be a bit more dense, which would bear on the payload capacity of the cheaper variants.

Then of course there is always the possibility of using different suspension and braking components in different variants of CT to achieve roughly the same payload capacity, even if pack weight and drive train weight do bear on the subject. The tri-motor may just have a beefier air suspension, brake calipers, etc. over the cheaper trucks.

I think you did hit the nail on the head regarding pack variants - it wouldn't surprise me to see a long-range dual motor variant, for example, if Tesla thinks there is market demand for it. I don't think they'll take that kind of decision lightly until it gets relatively easy for them to build these things (more variants = more manufacturing complexity).

 

[Zooman001]

It wouldn't be a big surprise, I suppose, for these numbers to become a bit different/more precise as the detailed design effort progresses, but it is probably also helpful to remember from Battery Day that Tesla intends to diversify its approach to battery cathode make-up as a function of vehicle demands. The higher capacity batteries may not just be larger/heavier. It is possible, just by using more nickel in the cathode (at greater expense) to produce a higher-capacity pack that doesn't weigh a lot more than a lower capacity one.

While Tesla implied they would go with "High Nickel" packs for Cybertruck and Semi, I don't think that takes using cheaper iron-based or nickel+manganese cathodes off the table for cheaper, lower-range versions of CT. These might be a bit more dense, which would bear on the payload capacity of the cheaper variants.

Then of course there is always the possibility of using different suspension and braking components in different variants of CT to achieve roughly the same payload capacity, even if pack weight and drive train weight do bear on the subject. The tri-motor may just have a beefier air suspension, brake calipers, etc. over the cheaper trucks.

I think you did hit the nail on the head regarding pack variants - it wouldn't surprise me to see a long-range dual motor variant, for example, if Tesla thinks there is market demand for it. I don't think they'll take that kind of decision lightly until it gets relatively easy for them to build these things (more variants = more manufacturing complexity).

Very good points, I hadn’t really considered different composition of packs for different models

 

[alan auerbach]

I feel like I am missing something, all three models of the CT are advertised as having a 3500lb payload. But shouldn’t the tri motor with the 500 mile range be less. The extra weight of the motors plus the much bigger battery pack should subtract from the GVWR and equal a smaller payload.

Also if you can make the tri motor go 500 miles why wouldn’t that battery pack be put in the dual and single motor and have an even better range?

You indicated elsewhere that your concern is trailer weight, not truck-bed carrying capacity.

In one sense there's no practical limit on how heavy a trailer can be -- given the right conditions. Snowy hills differ from dry level concrete -- picture how many rail cars a locomotive can pull on a flat run. Other variables are the wheels (brakes, tires/rims, drive system), the hitch design, the trailer design and how it's loaded, braking control differential (tow-er vs tow-ee), and especially how you drive.

The official posted limit on how much weight you can pull is a compromise decided on by the maker's depts for sales, legal, and engineering. If you're not concerned with violating some towing statute, or with suing the truck company if you lose control, you can tow way more than the nominal amount -- under the right conditions. But with your experience I'm sure you know all that.

 

[Challeco]

What's in your truck won't change your towing capacity appreciably, beyond model, because of those battery packs being down low balanced weight.

Just get the tri motor.

-Crissa

Gross vehicle weight does matter to commercial operations. It is a matter of taxes as well as transportation law. I am a mere civilian, however, what I understand of Zooman001's question is the gross vehicle weight matters to what jobs he may or may not contract.

 

[Luke42]

Very good points, I hadn’t really considered different composition of packs for different models

They haven't said they *wouldn't* use LiFePO4 cells in tabless 4680 packaging for the short-range batteries, and high-nickel lithium cells in 4680s for the long-range batteries.

If Tesla went that route, the long-range and short-range packs might weigh about the same. LiFePO4 batteries are *great* batteries -- they're safer, higher-amperage, longer-lasting, and more failure-tolerant than most other lithium chemistries. The only drawback is that they're heavier per kWh when compared to the other lithium chemistries. If you have some extra battery-weight in the budget, spending it on the LiFePO4 battery chemistry seems like a reasonable choice.

Tesla is already using LiFePO4 batteries in the short-range Chinese variants short-range 3/Y vehicles. Apparently Chinese customers are not as range-obsessed as we are.

Anyway, it's a fun hypothesis to think about.

Of course, as with all engineering, the devil is in the details.

 

[Crissa]

Tesla has no LiFePO4 production, especially not in the US. (In China they buy them from a third party.)

The Cybertrucks as ordered will not have them.

Gross vehicle weight does matter to commercial operations.

I suppose. The Cybertruck will qualify for the commercial vehicle tax credit. I wonder if I should incorporate just to get it. Naw, I don't approve of such things.

500lbs isnt going to change things much, tho.

-Crissa

 

[TheLastStarfighter]

I feel like I am missing something, all three models of the CT are advertised as having a 3500lb payload. But shouldn’t the tri motor with the 500 mile range be less. The extra weight of the motors plus the much bigger battery pack should subtract from the GVWR and equal a smaller payload.

Also if you can make the tri motor go 500 miles why wouldn’t that battery pack be put in the dual and single motor and have an even better range?

In the motortrend article where they had early access to the CT, they discussed the placement of the battery. It's in the center and does not stretch over the rear wheels to prevent impact on the payload capacity. In fact, it stops well short of the rear, as they have the compartment for the bed over to roll into. So at most you have 50% of the increased battery weight to account for, probably less. Maybe 25%? An 85kw Tesla battery was 1200lbs. We don't know the size of the CT battery, but the 500 mile range claimed for the Tri is not double the Dual. We don't know the battery types, either. The Single and Dual may use the old style, while the Tri may use the new type from Battery Day. They claimed numbers like 10% reduction in mass with 16% increase in range vs the same cells. If you take that and apply it to the range with a goal of keeping the weight the same, you increase range by 16%, then increase the size of the battery another 10% without changing mass. That means the new tech can get you 1.28X the range at the same weight. The claim is the Tri has 40% more range than the dual, so they only need another 12%. So they make the battery a little bigger still and you're still only about an extra 100lbs in weight. If less than half of that weight is over the rear wheels, we might be talking 40lbs. If the additional motor in the tri weighs 70lbs, the total impact on the payload might be 110lbs. So virtually nothing. It's reasonable to think that the payload of the Tri is 3500lbs, while the Dual might be 3600lbs, but who cares?!?

 

[Luke42]

Tesla has no LiFePO4 production, especially not in the US. (In China they buy them from a third party.)

You're right -- I remember, now!

It looks like Tesla is buying their LiFePO4 cells from CATL:
https://cleantechnica.com/2020/11/01/tesla-model-3-with-new-lfp-battery-now-supercharges-even-faster/#:~:text=Tesla's LFP supplier, CATL, is,chemistry to other EV makers.

LiFePO4s are good batteries, though, if they fit within the weight and $ budgets.

 

[Crissa]

Elon said '10% vehicle weight' for a Model 3 that's 300-400 pounds. Or about a third of the battery pack weight.

The weight savings of the integrated battery pack should be higher for larger battery packs.

It's really unlikely that they would use the old-style battery packs in any version of the Cybertruck.

-Crissa