Flat Tow support for Slate truck in the works [confirmed]

[Tran]

I asked about flat towing support for the Slate truck and here was their confirmation:

Hi Joe,​

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Great question! Towing a Slate behind a motorhome is exactly the kind of adventurous, off-grid thinking we're excited to see from future drivers.​

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We're happy to share that flat towing is actively in the works to be supported for Slate, including highway towing behind larger vehicles like RVs. Stay tuned for more specific guidelines and recommendations as we get closer to launch to make sure everything's smooth and road-trip ready.​

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Let us know if you'd like to be added to our updates list for towing and travel-related features!​

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Cheers:+​

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Kathryn || Slate agent team​

 

[Saint Alban]

Excuse my ignorance, I’m unfamiliar with this. What does it mean for a vehicle to have flat towing support? I thought you could do this with any vehicle.

 

[YDR37]

Excuse my ignorance, I’m unfamiliar with this. What does it mean for a vehicle to have flat towing support? I thought you could do this with any vehicle.

Nope. Always check the manual to see if flat towing is supported, because it may not be. If it's not, flat towing can seriously damage the transmission. Even if flat towing is supported, there may be special instructions to put it into flat-towing mode.

You can usually flat tow vehicles with manual transmissions. But if a vehicle has an automatic transmission (which of course is the vast majority of new vehicles), then all bets are off.

You can probably flat tow if the vehicle has an automatic transmission and a traditional four-wheel drive system with a transfer case, but it may not be straightforward. For example, you can flat tow a 2023 F-150 4x4, but according to the manual, putting it into "Neutral Tow Mode" requires 11 steps, including setting "Temporary Neutral Mode", which is 7 more steps. Then there are 9 steps to exit "Neutral Tow Mode".

Try this website (or your owner's manual) for more info.

 

[Saint Alban]

Nope. Always check the manual to see if flat towing is supported, because it may not be. If it's not, flat towing can seriously damage the transmission. Even if flat towing is supported, there may be special instructions to put it into flat-towing mode.

You can usually flat tow vehicles with manual transmissions. But if a vehicle has an automatic transmission (which of course is the vast majority of new vehicles), then all bets are off.

You can probably flat tow if the vehicle has an automatic transmission and a traditional four-wheel drive system with a transfer case, but it may not be straightforward. For example, you can flat tow a 2023 F-150 4x4, but according to the manual, putting it into "Neutral Tow Mode" requires 11 steps, including setting "Temporary Neutral Mode", which is 7 more steps. Then there are 9 steps to exit "Neutral Tow Model".

Try this website (or your owner's manual) for more info.

Damn, I didn’t know it was that complicated. Thanks.

 

[EVmodeler]

The Slate will likely have a permanent magnet motor. PM motors will act like a generator since they have built-in excitation (the magnets) even when “off” and can generate very high voltages when operated above “base” speed (which I estimate is in the low 40 mph range- working on a model The inverter is likely designed to manage this situation (at least for a short time) in case of some kind of failure, like an HV battery fault.
Some electric axle systems are designed for adding to one axle to make a hybrid with an engine (and possibly other motors) on the other axle. Some of the Ford hybrids are of this design.
Some motor suppliers offer an axle disconnect for these applications, or even for a two motor AWD EV. The disconnect lets the axle free-wheel to reduce the drag from the PM motor when it’s not needed or used. I am not sure if any of these disconnect options have made it to production in EVs or hybrids. It costs extra, and is a relatively low loss.
Slate may be looking into this sort of mechanical disconnect system to allow flat towing. There are other ways to achieve this function with the inverter, but they may require some of the vehicle to “on” or a special mode.
There are axle disconnects that can be added to conventional vehicles to allow flat towing with a transmission that otherwise would not allow it.

And please, don’t get started on “towing with regen to charge the battery” ! Yes it is possible, but requires quite a bit of controls, and a lot can go wrong. (I have done it in a controlled environment on a chassis dyno).

 

[YDR37]

Always check the manual to see if flat towing is supported, because it may not be. If it's not, flat towing can seriously damage the transmission. Even if flat towing is supported, there may be special instructions to put it into flat-towing mode.

At this point, I don't know of any BEVs (excluding hybrids) on the market that can be flat towed. If it is confirmed that the Slate does have that capability, it could be the first.

I haven't checked every current EV model, so I could be wrong. If you know otherwise, feel free to correct me.

 

[AZFox]

For those wondering, the reason an automatic transmission needs the engine running is because the transmission's innards require lubrication that's provided by the torque converter, which acts as a fluid pump. The pumping part of a torque converter is bolted to the engine's flywheel, hence the engine needs to be running for the pumping to happen.

I've heard that in an emergency you can safely flat-tow an automatic by running the engine at idle and shifting the transmission to neutral. Cannot confirm this, so YMMV.