How do you feel about Slate's towing capacity?

[E90400K]

Yeah everyone is focused on the ai link but not the fact being unitized near the rear reduces the amount of materials to build up trailering and support structures.

the hitch weight limits on normal trucks are highest the closer the hitch is to the rear axle, with a 5th wheel being strongest mounting directly above the rear axle.

Reduces lever arm forces and twisting forces on the frame to the front as well.




All modern truck drivetrains ice and EV must support continuous max output in hot desert conditions or have a extremely conservative downrating mechanism to prevent damage as even during normal aging and use nearly everyone will hit a cooling limit at some point.

If it can overheat it’s a bad design, it needs to be able to downrate non-destructibly when the system gets near limits. All modern transmissions and engines Have extensive sensors to prevent damage.

Agree. The Honda Ridgeline is basically a Honda Pilot with a pickup bed. It can tow 5,000 pounds. I think the Slate's structure is even more robust than a unibody because it has structural frame elements that make up the bed walls and tied into the front cabin structure.

My opinion is, the Slate just needs more cooling capacity. The issue being the cabin AC/battery cooling system can't handle a towed load over 1,000 as currently outfitted. Asking it to tow just 2,500 to 3,500 pounds is not out of range for a small pickup in that market segment.

 

[GaRailroader]

Agree. The Honda Ridgeline is basically a Honda Pilot with a pickup bed. It can tow 5,000 pounds. I think the Slate's structure is even more robust than a unibody because it has structural frame elements that make up the bed walls and tied into the front cabin structure.

My opinion is, the Slate just needs more cooling capacity. The issue being the cabin AC/battery cooling system can't handle a towed load over 1,000 as currently outfitted. Asking it to tow just 2,500 to 3,500 pounds is not out of range for a small pickup in that market segment.

I agree that structurally the Slate should be able to handle a 2500-3500 tow rating. With the way they have indicated tow rating is a compromise for range it makes me think it was a business decision they made in reduction gear selection. Perhaps they have gone with a tall final gear ratio like 2.73s or 3.23s equivalent on conventional drivetrain and if they had gone with something lower like 4.11s then they would have been able to support a higher tow rating but perhaps EPA rating with that configuration is only 120 miles instead of 150. Most buyers would likely favor a 1000 lb tow limit to get the 150 mile range instead of 120 with the higher tow rating. Obviously I don’t know for certain, just seems to be the most likely explanation in my mind.

 

[danielt1263]

I agree that structurally the Slate should be able to handle a 2500-3500 tow rating. With the way they have indicated tow rating is a compromise for range it makes me think it was a business decision they made in reduction gear selection. Perhaps they have gone with a tall final gear ratio like 2.73s or 3.23s equivalent on conventional drivetrain and if they had gone with something lower like 4.11s then they would have been able to support a higher tow rating but perhaps EPA rating with that configuration is only 120 miles instead of 150. Most buyers would likely favor a 1000 lb tow limit to get the 150 mile range instead of 120 with the higher tow rating. Obviously I don’t know for certain, just seems to be the most likely explanation in my mind.

Same here. And of course a two speed transmission adds complexity... It will be interesting to see if any after market companies offer a two speed manual transmission...

 

[GaRailroader]

Same here. And of course a two speed transmission adds complexity... It will be interesting to see if any after market companies offer a two speed manual transmission...

Shortly after doing a real world test in the 1st production intent Aptera, Aptera announced this partnership with inmotive which offers a low cost 2 speed transmission. Their goal was always 10 miles per kWh and at came in at 6 or 7 if I remember correctly.

https://aptera.us/inmotive-ingear/

 

[E90400K]

Same here. And of course a two speed transmission adds complexity... It will be interesting to see if any after market companies offer a two speed manual transmission...

Going down a rabbit hole...

I don't think it needs a 2-speed transmission to up the towing capacity. It has 200 HP and 190 TQ of electric power. Small ICEV pickups of the '80s towed more with much less horsepower and torque.

It's just a range limit issue. Slate should add some cooling capacity and not worry about the range hit, everyone knows electric towing eats electrons; it's not like the EPA rates EVs for towing efficiency, so who cares.

 

[Tom Sawyer]

It will be interesting to see if any after market companies offer a two speed manual transmission...

Interesting indeed!

How many other EVs (not from a DIY kit but from a mainstream manufacturer (Has Aptera even reached production?)) offer a multi-speed transmission of any sort?

Just because I haven't heard of any doesn't mean it's either another hallucination or wishful thinking.

 

[danielt1263]

Interesting indeed!

How many other EVs (not from a DIY kit but from a mainstream manufacturer (Has Aptera even reached production?)) offer a multi-speed transmission of any sort?

Just because I haven't heard of any doesn't mean it's either another hallucination or wishful thinking.

I believe one of the high end, European SUVs has a 2 speed transmission.
I really think though, that the towing limit is more a factor of engine and battery cooling.

 

[ElectricShitbox]

Interesting indeed!

How many other EVs (not from a DIY kit but from a mainstream manufacturer (Has Aptera even reached production?)) offer a multi-speed transmission of any sort?

Just because I haven't heard of any doesn't mean it's either another hallucination or wishful thinking.

Porsche Taycan has a 2 speed transmission on the rear motor. I think there's a couple others, but it's not common.

 

[GaRailroader]

Porsche Taycan has a 2 speed transmission on the rear motor. I think there's a couple others, but it's not common.

Tesla also had a 2 speed on the about 1 years of production of the Roadster but discontinued due to reliability issues. The Roadster was powered by a single induction motor which works better at lower RPMs than high. With the newer EVs frequently having dual motors they typically put a permanent magnet motor in the rear which is better at higher RPM and put an induction motor in the front which performs better at lower RPMs. This combination makes the need for a 2 speed less prevalent unless it is a single motor application or they don't want to use rare earth metals.

 

[Driven5]

I think the Slate's structure is even more robust than a unibody because it has structural frame elements that make up the bed walls and tied into the front cabin structure.

Slate will not be 'even more robust than a unibody' because it is a unibody. That's what it means to have 'structural frame elements that make up the bed walls and tied into the front cabin structure'. The Ridgeline is constructed much the same way, but with more of that structure. But don't just take my word for it...

we started with a frame, architecture, and because it was gonna be a truck, we said it’s gotta have a frame, but then we started looking at efficient design and it really morphs itself into a proper body in white that wraps itself around the battery such that you have the battery below the floor and, and so that that frame ended up morphing itself into a unibody

Sure it may have integrated 'rails', but so do many (most for modern?) other unibodies. So the hitch is mounted to relatively thin unibody-type sheet metal structure, and then cantilevered out to load those mounts in a manner which is known to basically cut tongue weight ratings in half...

Sure they may design a hitch that doesn't need the extension itself, but the that doesn't change the physics loading into the sheet metal mounting points. So for those saying it *should* have at least a 2k tow rating, that's structurally where it appears to have gone.

Perhaps they have gone with a tall final gear ratio like 2.73s or 3.23s equivalent on conventional drivetrain and if they had gone with something lower like 4.11s then they would have been able to support a higher tow rating...

They geared it with the motor running out of rpm at just over 90mph, which more people are worried about than are the towing capacity... So there's no way they could get away with any shorter of gearing than that, and the idea of a 2-speed transmission misses the plot entirely.

 

[GaRailroader]

They geared it with the motor running out of rpm at just over 90mph, which more people are worried about than are the towing capacity... So there's no way they could get away with any shorter of gearing than that, and the idea of a 2-speed transmission misses the plot entirely.

Is the 90 mph top speed due to the RPM limit of the motor or is that where aero drag and all the drags equal motor output at that RPM with the gearing selected?

 

[kvermeer]

Is the 90 mph top speed due to the RPM limit of the motor or is that where aero drag and all the drags equal motor output at that RPM with the gearing selected?

It's not the aero power limit, at least not in the short term. Other vehicles that have the same amount of power as a Slate (and slower acceleration due to pauses for gearboxes and narrow ICE power bands) include the 155 MPH, 200 HP Ford Fiesta ST, the 137 MPH, 205 HP Honda Civic SI, and the 145 MPH, 175 HP Mini Cooper S. Those hatches are shorter and more aero than a Slate, but not by that much.

It might be power in the long term, the motor might be rated for 200 horsepower in short bursts to accelerate but be unable to maintain 200 horsepower hours of highway cruising. And to be fair, neither can those ICE vehicles - if you pinned them to the redline, they'd overheat in minutes.

Also, it appears the tires are "H" speed code (130 mph) Kenda Klever S/T, so that's at least one other limiting factor...

I do think that another factor is a lack of appropriate test tracks on which to attempt a top-speed run in a Slate. There's not a single road in the country with a 90 MPH speed limit, and if you're at a track day or on a drag strip, surely there are more appropriate vehicles with which to go racing.

I don't want Slate to have made engineering tradeoffs made that compromise daily driving in any way for the sake of 100+ mph top speed attempts... I'd much rather compromise top speed for the sake of low-end torque.

 

[cadblu]

Other vehicles that have the same amount of power as a Slate (and slower acceleration due to pauses for gearboxes and narrow ICE power bands) include the 155 MPH, 200 HP Ford Fiesta ST, the 137 MPH, 205 HP Honda Civic SI, and the 145 MPH, 175 HP Mini Cooper S. Those hatches are shorter and more aero than a Slate, but not by that much.

I’m not sure why, but somehow I would feel way more comfortable going 90+ mph in any of the vehicles you mentioned than in a Slate. For me, the tall upright profile, short wheelbase, and narrow track would be nerve wracking in a high speed situation, and somehow I don’t see the Slate being nimble in an evasive maneuver at speed. And wait till you see what high speed driving in a EV does to range. Therefore I’m not planning anything past 65 -70 mph unless someone can prove otherwise.

 

[E90400K]

Slate will not be 'even more robust than a unibody' because it is a unibody. That's what it means to have 'structural frame elements that make up the bed walls and tied into the front cabin structure'. The Ridgeline is constructed much the same way, but with more of that structure. But don't just take my word for it...
Sure it may have integrated 'rails', but so do many (most for modern?) other unibodies. So the hitch is mounted to relatively thin unibody-type sheet metal structure, and then cantilevered out to load those mounts in a manner which is known to basically cut tongue weight ratings in half...

Sure they may design a hitch that doesn't need the extension itself, but the that doesn't change the physics loading into the sheet metal mounting points. So for those saying it *should* have at least a 2k tow rating, that's structurally where it appears to have gone.


They geared it with the motor running out of rpm at just over 90mph, which more people are worried about than are the towing capacity... So there's no way they could get away with any shorter of gearing than that, and the idea of a 2-speed transmission misses the plot entirely.

Boxed sheet metal can be quite strong regardless of the gauge used to construct the boxed elements. While the Slate doesn't have a traditional ladder truck frame it does have a large frame rail battery box and very large frame rails that serve as the traditional rocker panels. Perhaps the tow kit would include a revised rear bumper that serves as the hitch much as small pickup trucks of the 1980's had a trailer ball that bolted directly to the step section of the bumper, which would reduce the lever effect of, what seems to be, a makeshift hitch system in the pics you posted of the prototype truck. 3,500 pounds is not a lot of weight to tow especially when a tongue weight of 200 to 350 pounds is normally the spec for a 2,000 - 3,500 pound loaded trailer.

 

[JoeBlow-Kokomo]

That is impressive! Perhaps I have been advertised into believing 4WD is more necessary than it actually is. I stand corrected.

Most "need' for 4wd was about no weight over the rear axle of pickup trucks. Put 150lbs of sand over each wheel well and trucks drive just fine in winter without 4wd. MIllions and millions of them. Including me. And I've owned 5 4wd vehicles. I live in northern Indiana, less than 60 miles from Michigan and have for all of my 67 years. Normal for needing 4wd was a couple of events a year. Some years not at all. Slate and most other EV's are built on a 'skateboard' chassis/battery pack at the lowest point of the car. And equally balanced over ALL FOUR WHEELS. So just like ALL FWD, VW Beetles and Chevy Covairs with RWD and rear engines, they will be dandy snow machines. Without the extra weight and handling loss of front wheel motor.