Engineering deep dive: Slate EV truck chassis, body, battery, safety, suspension, underbody undercarriage

[cvollers]

Agree, and what is holding back going to a 800V architecture? If it's cost, then perhaps that is indicative of the argument for the reasons why expensive BEV are expensive, they are built with better, more expensive components. How much really is being saved by deleting the fluff infotainment electronics and associated software?

I like the concept of decontenting the fluff, but any fresh BEV at this point should be nothing less than 800V.

I asked ChatGPT and got this result:

“1. Battery Size and Charging Speed Needs

• Smaller EVs typically have smaller battery packs (e.g., 30–50 kWh vs. 70–100+ kWh in larger EVs).
• These smaller packs don’t take as long to charge, even on 400V systems, so the time-saving benefit of 800V fast charging is marginal.

2. Cost and Complexity

• 800V systems require more expensive components, such as:
  • High-voltage inverters
  • More advanced insulation
  • Specialized charging hardware
• For low-cost EVs, keeping the bill of materials (BOM) low is essential. Adding 800V support increases cost without offering proportionate value to the target buyer.

3. Charging Infrastructure Compatibility

• 400V is still more common in public charging networks.
• Most users of small EVs charge at home or use slower public chargers, not ultra-fast stations where 800V would matter.

4. Thermal and Efficiency Gains are Smaller

• 800V systems reduce current for the same power level, which helps with thermal efficiency, but smaller EVs don’t draw high enough currents to significantly benefit.

In short, the advantages of 800V—faster charging, better efficiency at high power—are most useful for larger, long-range EVs. For small EVs, 400V is simpler, cheaper, and “good enough.””

 

[E90400K]

I asked ChatGPT and got this result:

“1. Battery Size and Charging Speed Needs

• Smaller EVs typically have smaller battery packs (e.g., 30–50 kWh vs. 70–100+ kWh in larger EVs).
• These smaller packs don’t take as long to charge, even on 400V systems, so the time-saving benefit of 800V fast charging is marginal.

2. Cost and Complexity

• 800V systems require more expensive components, such as:
  • High-voltage inverters
  • More advanced insulation
  • Specialized charging hardware
• For low-cost EVs, keeping the bill of materials (BOM) low is essential. Adding 800V support increases cost without offering proportionate value to the target buyer.

3. Charging Infrastructure Compatibility

• 400V is still more common in public charging networks.
• Most users of small EVs charge at home or use slower public chargers, not ultra-fast stations where 800V would matter.

4. Thermal and Efficiency Gains are Smaller

• 800V systems reduce current for the same power level, which helps with thermal efficiency, but smaller EVs don’t draw high enough currents to significantly benefit.

In short, the advantages of 800V—faster charging, better efficiency at high power—are most useful for larger, long-range EVs. For small EVs, 400V is simpler, cheaper, and “good enough.””

So Chap GP seems to confirm it's a cost issue, which makes my point that more expensive EV are expensive because they use better, more expensive components for better charging performance.

Chap GP just leads back to my concern about market acceptance. People on the lower income level of society don't own a single-family home that has access to private overnight EV charging. They will have to use the public DCFC network to charge their Slate, which is just 90 miles of usable range (20% to 80% SOC), which will take 30 minutes. To get to 150 miles of range at 100% SOC will probably take an hour or more. Drive 10,000 miles a year at 90 miles a clip and that's 56 hours spent fueling a Slate.

A Ford Maverick 2.0L Ecoboost has 400 miles of range per tank and at its EPA rating of 26 MPG, it will need around 24 fills of the tank to travel 10,000 miles per year. 24 tank fills at 5 minutes each is just 2 hours per year to fuel the Maverick.

 

[Chadsfantasygarage]

Maybe Slate 2 will get a longer wheelbase and two more doors. And power windows/mirrors. But please don’t add screens.

Yes that makes sense to me. Perhaps a long enough body to accommodate an optional inclosed 3rd row that can be converted back into a smaller pickup truck with a mid gate to allow for longer items without making the overall length too long?

 

[cvollers]

Yes that makes sense to me. Perhaps a long enough body to accommodate an optional inclosed 3rd row that can be converted back into a smaller pickup truck with a mid gate to allow for longer items without making the overall length too long?

I like your image but think it’s a little too long for what Slate might do. I doubt the bed will get longer than what they have now so the C pillar will have the same relationship to the rear door as the current B pillar does to the front door.

 

[metroshot]

I don't care if the battery is 400 or 800v.
I just want to access Tesla Superchargers where I normally charge my Mach E.
With such a small battery, it should be enough time to get a coffee or bathroom trip.

 

[Johnny-Longtorso]

Based on the specs I've seen this is very, very optimistic. (my guestimate being that's near 1k pounds based on ~ 65# for a 4x8 sheet of 3/4" MDF)

It may fit, but I don't see the suspension dealing with it, nor do I see it moving this material safely for more than a few blocks.

Am I wrong?

 

[cvollers]

Based on the specs I've seen this is very, very optimistic. (my guestimate being that's near 1k pounds based on ~ 65# for a 4x8 sheet of 3/4" MDF)

It may fit, but I don't see the suspension dealing with it, nor do I see it moving this material safely for more than a few blocks.

Am I wrong?

The quoted load rating is 1400 pounds.

 

[Johnny-Longtorso]

The quoted load rating is 1400 pounds.

Ah, OK.

So with me@ 240# that would be right on the edge.

 

[metroshot]

Based on the specs I've seen this is very, very optimistic. (my guestimate being that's near 1k pounds based on ~ 65# for a 4x8 sheet of 3/4" MDF)

It may fit, but I don't see the suspension dealing with it, nor do I see it moving this material safely for more than a few blocks.

Am I wrong?

EVs are amazing - as long as the load is not taller than the cab height, it will get almost the same range due to aerodynamics.

When I had the Ford Lightning EV, it would haul half ton weights in the bed without any issue.

 

[Roy]

Would it be an accurate guess to say the Slate will have regen braking. That seems to be a basic part of a viable EV.

 

[Chadsfantasygarage]

I like your image but think it’s a little too long for what Slate might do. I doubt the bed will get longer than what they have now so the C pillar will have the same relationship to the rear door as the current B pillar does to the front door.

I'm not sure exactly what you are saying about length, but if you keep the 5 foot bed from the current slate AND add rear doors you actually end up with something even longer then my previous green render. My render below is what a quad cab slate WITH a 5 foot bed would look like.

 

[metroshot]

Would it be an accurate guess to say the Slate will have regen braking. That seems to be a basic part of a viable EV.

Yes, makes sense for EV and PHEV to have that.

I just hope Slate does not do what Tesla did - 1PD only.

I prefer 2PD with light regen while coasting - like my Mach E.

 

[Roy]

I’m not sure who has put-up this forum. I hope it is somebody from Slate. And forgive me if these questions have been answered on the Slate Auto page or someplace in all of the product announcement presentations.

What type and kind of regen braking does the Slate have?

Will there be a plug or a wire access point for trailer/towing lights?

Does Slate have a list of receiver hitches which will fit the Slate?

Besides the accessory external spare wheel mount, where does the spare reside in the base
vehicle, and is it a full size tire and rim?

What size is the wheel bolt pattern?

What on the Slate will not be DIY for repair and rebuild?

Has Slate gotten any estimates, from a knowledgeable insurance industry underwriter, as to the expected insurance coverage rate?

Besides the announced Slate University, for the gear head DIY crowd, will Slate provide a repair/maintenance procedure manual which can be printed out?

For the camping/hiking/cycling crowd, will there be a plug or adapter port for a solar panel to charge off-grid or for camp lights and a fridge, or what ever?

Is Slate actively recruiting possible independent shops for warranty repair work?

How would an interested independent shop start the process to be a vendor?


If this is the wrong place to ask all of these questions, let me know and I will move it.

 

[cvollers]

I'm not sure exactly what you are saying about length, but if you keep the 5 foot bed from the current slate AND add rear doors you actually end up with something even longer then my previous green render. My render below is what a quad cab slate WITH a 5 foot bed would look like.

Ahhhh…ok my bad. I think just a slightly longer version of v1. No truck bed but an open (with roll bar) or enclosed rear section and those four doors. Oh and a lift. Keep the lift gate and add the spare tire rear bumper mount. Like a poor man’s version of the ROX Toyota built for SEMA.

 

[lgerger]

t any fresh BEV at this point should be nothing less than 800V.

In my view, 400V was likely chosen due to reduced cost (a major selling point of this vehicle), and more readily available parts. I personally think that was the right decision from a company perspective. I don't like the thicker and heavier cables, and less efficient charging of 400V, but that's not what this brand is aiming for (at least in their first iteration).