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ExCivilian

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The laws of physics aren't the problem here.
There's going to be a balance between stability and regen. It's clearly not a binary where the trailer wraps around the truck if the trailer brakes don't go full on. Ultimately you'll want more "backpressure" from the trailer on an EV truck than an ICE truck.
There is no safe way to "back pressure" a tow vehicle in the way you're suggesting. The suggestion is absurd and violates the laws of physics that you ignored in your earlier statement.

If you want to try and thread a needle of rebutting sound towing principles with trolling remarks like, "the brakes don't go full on," which no one ever claimed and would be as dangerous as them never activating while towing downhill that's fine but it indicates to me that you've never towed these types of loads in those types of conditions.

It is a binary. The trailer brakes must activate earlier than the towing vehicle's or the towed vehicle will do something unexpected. If you don't understand that it's because you've never towed in inclement weather and possibly may not have much experience towing at all. The types of questions in these threads and the responses they're getting indicate to me that there's a lot of people in those two groups expecting to strap 8K lbs of deadly mass to their fancy new toy and scoot up and down the public roadways without any inkling of what's going on under the hood. Both groups of people need to understand the dangers and physics involved in towing before they kill themselves and/or someone else.
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LightningShow

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Care to explain why trailers with GVWR under 3000 don't have brakes? Because you seem to be certain that this will result in the trailer ending up sideways any time the tow vehicle brakes.
 

vandy1981

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There is no safe way to "back pressure" a tow vehicle in the way you're suggesting. The suggestion is absurd and violates the laws of physics that you ignored in your earlier statement.
Just something to consider. The F150's integrated trailer brake controller relies on pedal input for trailer brake modulation. If you are saying that the trailer brakes activate with engine braking (or regen braking in the F150L's case), then it would need to have some sort of inertia-based function in the controller. AFAIK, the F150 does not have this.

You seem incredibly knowledgeable about towing--can you provide some sort of reference for how engine braking works with trailer brakes in the F150 ICE or how regen works with trailer brakes in the F150L?
 

ExCivilian

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Care to explain why trailers with GVWR under 3000 don't have brakes? Because you seem to be certain that this will result in the trailer ending up sideways any time the tow vehicle brakes.
What do you think this has to do with a 10,000lb load down a snowy, icy 7% grade?
 

LightningShow

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What do you think this has to do with a 10,000lb load down a snowy, icy 7% grade?
Oh, is that what you thought we were talking about?
 

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guerro

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Context buddy....that picture means nothing. Is that coasting downhill? In the hot Temps? Its a valid question.
Looks like it reads 98 degrees outside temp
 

SomebodyInGNV

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The towing prowess debate for EV trucks is inevitable. No doubt. It'll be entertaining. ... Still, it'll be fun to watch the keyboard war.
Now, instead of endless diesel/gas arguments, we'll have diesel/gas/EV arguments.
 

Kev12345

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Was TFL involved in the Ike gauntlet test? Is there a video other than the Ford B roll footage?
 

LightningShow

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TFL wasn't involved. They confirmed on Twitter.
 

beatle

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Just something to consider. The F150's integrated trailer brake controller relies on pedal input for trailer brake modulation. If you are saying that the trailer brakes activate with engine braking (or regen braking in the F150L's case), then it would need to have some sort of inertia-based function in the controller. AFAIK, the F150 does not have this.

You seem incredibly knowledgeable about towing--can you provide some sort of reference for how engine braking works with trailer brakes in the F150 ICE or how regen works with trailer brakes in the F150L?
Regen is a lot stronger than engine braking. Engine braking these days is pretty weak in order to maximize efficiency. Unlike regen, engine braking only hurts efficiency. I think at some point in the regen gradient, the truck will trigger the trailer's brakes just in the way it triggers the brake lights once a certain deceleration threshold occurs. As you stated, the ICE F150 doesn't trigger the trailer brakes until you actually hit the brake pedal - likely because engine braking isn't all that strong.
 

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duallyben

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Regen is a lot stronger than engine braking. Engine braking these days is pretty weak in order to maximize efficiency. Unlike regen, engine braking only hurts efficiency. I think at some point in the regen gradient, the truck will trigger the trailer's brakes just in the way it triggers the brake lights once a certain deceleration threshold occurs. As you stated, the ICE F150 doesn't trigger the trailer brakes until you actually hit the brake pedal - likely because engine braking isn't all that strong.
Engine braking what is your baseline here? Ford or Gm HD with 10 sp, they suck balls, ram hd with tow mode on can throw you forward. Those are exhaust breaks, my international with L9 Cummins and a built in engine brake slows similar to the ram. I sold the GM, own and personally drive the other 3 regularly.
In saying all that regen braking will need to account for a trailer and Rivian having it off was a legal thing. Same idea why on my ford and GM the exhaust brake had to be enabled every day.
 

beatle

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My reference points are a Ridgeline, Tacoma, and other automatic passenger vehicles with slushboxes, so no diesels or anything with a turbo. My Miata is pretty low compression by today's standards but will still engine brake pretty well, especially at higher RPM and lower gears. I don't tow with the Miata though...
 

vandy1981

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I think at some point in the regen gradient, the truck will trigger the trailer's brakes just in the way it triggers the brake lights once a certain deceleration threshold occurs.
I bought a trailer brake tester because I'm curious about how the Lightning handles braking when it thinks there's a trailer connected.

There was minimal, if any, engagement of the trailer brakes with normal regen when the the trailer brake gain was turned up to its max level. It didn't matter if I was in normal or trailer mode, if cruise control was enabled, or if I had 1 pedal driving enabled. Trailer braking was also decoupled from the brake light that's triggered by deceleration with regen.

Hard braking did engage trailer brakes and there was minimal engagement with low-speed stops at intersections.

I'll do some more testing, but it appears that the truck doesn't apply the trailer brakes with normal regen which definitely helps with effiiciency.

Take this all with a grain of salt. I didn't have a chance to use the tester on our old gas truck so I don't know if the behavior would be the same. I did not have a trailer attached when I did the test because the tester blocks the 7-pin connector when in use. I don't know how this would affect trailer brake engagement under normal braking. I also did not test it at extreme grades like you'd have with the Ike Challenge.
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