I can tell you, the lightning does realize more regen with my 7300lb trailer attached. Particularly down hill.

But the law of the conservation of energy means this is not free,

 

I agree there is some level of regen, as it is today, depending on your trailer gain setting. Maybe this is all the adjustment we may have. However, can more be had through trailer break control optimization /modulaton where the friction brakes are used less in lieu of regen. Thanks for your response.

 

This would work fine if you installed a regenerative braking system on the trailer. Basically, that would entail installing an electric motor on the trailer axles and feeding the power back to the truck charging system via a custom electrical harness. This is why folks are designing some trailers, especially travel trailers, for use with EVs.

Remember that it’s not the weight that has the greatest impact on towing efficiency it’s the aerodynamics, or lack thereof, of the trailers.

 

This would work fine if you installed a regenerative braking system on the trailer. Basically, that would entail installing an electric motor on the trailer axles and feeding the power back to the truck charging system via a custom electrical harness. This is why folks are designing some trailers, especially travel trailers, for use with EVs.

Remember that it’s not the weight that has the greatest impact on towing efficiency it’s the aerodynamics, or lack thereof, of the trailers.

Yes agreed, however this is a purists way of thinking. Having to buy more equipment of limited use. I also agree that EV trailers are also being developed to provide for longer range. This is good and may provide more future options. However, this doesn’t cover the personal/commercial world that simply want to use their existing trailers for longer tow range. Is there something that can be modified or optimized to maximize range with the current schema? Maybe my thoughts are bit optimistic in what it may add but has someone really understood what can be gained, if anything, by looking at the interaction of the trailer brake system with the trucks system?
For braking, weight is the predominant factor because it is momentum which is determined by the mass of the vehicle that if reduced by regen is energy that can be recaptured. Thanks for your reply and input.

 

Typically, you want your trailer to brake first for stability. The lower you turn your break controller down, the less the trailer brakes and the more regen you get. You can control that balance.

Have a play and let us know.

fyi: my trailer is an Airstream, not bad on aero.

 

As we've towed our 3,800lb single axle camper 25,000+ miles, I'm not sure I understand the original question, or concern, as trailer 'brakes' don't get applied until actual PHYSICAL braking is applied by the tow vehicle, the LIGHTNING. This means that the tow vehicle is ALREADY applying it's own brakes, and therefore, any REGEN of concern is happening at the same time, whether or NOT the trailer brakes are being applied. Matter-of-fact, REGEN is happening potentially BEFORE braking is applied, when going down hills, when letting off the GO pedal, etc.
The trailer 'pushing' the truck, such as when going down hills, is already going to be adding to REGEN that would not already be a part of the equation, depending on speed, conditions, etc.

In essence, the towed-weight and/or aero of the trailer are going to 'hurt' efficiencies when under regular towing scenarios, or especially uphill, but the trailer then gives 'back' some efficiencies when going downhill, or in similar situations where the trailer is now 'pushing' the truck, adding more Regen than might normally be a part of the equation.

But, there is no way to change the dynamics of the laws of physics, weight, momentum, aero, etc... it is what it is - although, as we've all come to conclude, SPEED is the main 'hurt', or 'help', depending on how you make use of it. Anytime your foot is not on the GO pedal, you are doing well. But, most drivers don't want to slow down, they want to maintain speed, which is part of what hurts towing efficiencies, especially when hills or mountains are involved.

Rather than maintain speed, maintain the amount of the GO pedal pressure, instead(otherwise known as the KW output of power from the battery).
I would like to deploy a special cruise-based DRIVE MODE Towing Setting for this exact reason: 'MAX POWER' mode, where you set the amount of KW of power as the Max Output, while towing.
You then set the CRUISE to ON, let your foot off the pedal, and have the truck maintain a speed, yes, but only up to this Max POWER OUTPUT, such as 25%. Under normal flat roadways, your 55mph set speed may be well within the max, yet, when you come into an uphill trajectory, the truck then uses no more than that max 25% KW output, even as slowing starts to occur.
Of course, as a driver, you can always add your foot to the equation, if necessary, for any situation, as needed. Some very LONG uphills may slow you to the point of needing additional speed, but for most scenarios, this would provide consistent KW power output, rather than the HUGE hits to the battery pack, to maintain a set speed, over the long run.

 

As we've towed our 3,800lb single axle camper 25,000+ miles, I'm not sure I understand the original question, or concern, as trailer 'brakes' don't get applied until actual PHYSICAL braking is applied by the tow vehicle, the LIGHTNING. This means that the tow vehicle is ALREADY applying it's own brakes, and therefore, any REGEN of concern is happening at the same time, whether or NOT the trailer brakes are being applied. Matter-of-fact, REGEN is happening potentially BEFORE braking is applied, when going down hills, when letting off the GO pedal, etc.
The trailer 'pushing' the truck, such as when going down hills, is already going to be adding to REGEN that would not already be a part of the equation, depending on speed, conditions, etc.

In essence, the towed-weight and/or aero of the trailer are going to 'hurt' efficiencies when under regular towing scenarios, or especially uphill, but the trailer then gives 'back' some efficiencies when going downhill, or in similar situations where the trailer is now 'pushing' the truck, adding more Regen than might normally be a part of the equation.

But, there is no way to change the dynamics of the laws of physics, weight, momentum, aero, etc... it is what it is - although, as we've all come to conclude, SPEED is the main 'hurt', or 'help', depending on how you make use of it. Anytime your foot is not on the GO pedal, you are doing well. But, most drivers don't want to slow down, they want to maintain speed, which is part of what hurts towing efficiencies, especially when hills or mountains are involved.

Rather than maintain speed, maintain the amount of the GO pedal pressure, instead(otherwise known as the KW output of power from the battery).
I would like to deploy a special cruise-based DRIVE MODE Towing Setting for this exact reason: 'MAX POWER' mode, where you set the amount of KW of power as the Max Output, while towing.
You then set the CRUISE to ON, let your foot off the pedal, and have the truck maintain a speed, yes, but only up to this Max POWER OUTPUT, such as 25%. Under normal flat roadways, your 55mph set speed may be well within the max, yet, when you come into an uphill trajectory, the truck then uses no more than that max 25% KW output, even as slowing starts to occur.
Of course, as a driver, you can always add your foot to the equation, if necessary, for any situation, as needed. Some very LONG uphills may slow you to the point of needing additional speed, but for most scenarios, this would provide consistent KW power output, rather than the HUGE hits to the battery pack, to maintain a set speed, over the long run.

I really like this idea of “Max Power”. This fits the idea of adjusting control parameters to get better efficiency. No new hardware, just better optimization of use for a specific task. For most towing trips this would increase range pending extreme environmental conditions. Autopilot for power, a kin to autopilot for speed. This would be a great driving mode to have available. Thanks for this great idea.

 

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Thanks guys for all the great input and information. I did not expect a specific solution. My only reason for asking this question is to understand if the additional momentum, which in many cases, the trailer may have more momentum (p=mV) then the truck itself. For example GSMBLUE’s 7300 lb. trailer can potentially have more convertible momentum than the 6800 lb. truck itself. Great to hear he gets some benefit when pulling his trailer based on using the trailer brake gain to maximize. I know this is a tough ask without a slave motor on the trailer for regen as Chasing Coral advocates. I also appreciate the Leaf to Lightning “out of the box” thinking about a potential way of maximizing towing regen. I trust that Ford Engineers are considering all of this and in doing so may provide innovative solutions that help keep battery size and weight manageable and still have adequate towing range ~>200 mi. for trailers 75-100% of specified towing weight, someday soon.

 

The Lightning uses regen when towing (when doing anything that involves moving and not hard, sudden braking).

Assuming no difference in wind resistance (i.e., the drag coefficient), the more mass the system has, the more regeneration one will see. However, the more energy it will take to move that mass in the first place. Since no system can be 100% efficient, a higher mass combination will use more energy than a lower mass combination.

That is just the way it is unless you're working with a very specific example like towing a trailer down a mountain. If you ignore the energy cost of getting the trailer up the mountain, the energy recovered going down will be greater for a higher mass trailer.

 

I tow a 34 foot camper and I use one pedal driving while towing. Didn't notice much difference with it on or off. I think the main issue is running on the highway with the wind resistance.

 

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Having towed a few trailers with my lightning, I can attest to the added regen in a few cases. A trailer with no brakes? Absolutely you get much of it back when slowing.
surge brakes? When just slowing, you get the regen benefits, but if you slow fast enough to engage the surge brakes, you lose the benefits.
electric brakes? I have no idea, don’t have the brake controller to know. I would be curious if the truck engages the trailer brakes when in one pedal mode.

 

Having towed a few trailers with my lightning, I can attest to the added regen in a few cases. A trailer with no brakes? Absolutely you get much of it back when slowing.
surge brakes? When just slowing, you get the regen benefits, but if you slow fast enough to engage the surge brakes, you lose the benefits.
electric brakes? I have no idea, don’t have the brake controller to know. I would be curious if the truck engages the trailer brakes when in one pedal mode.

Yes, that was my point. How smart is the brake controller? Does it maximize braking regen. We know the truck takes advantage of both downhill and braking regen from the trailer. But, to what degree of regen is coming from braking? We certainly hit on the point of brake gain adjustment and its effect on more or less regen. As GSM Blue has indicated. Maybe an automated gain adjust may help instead of a fixed gain. Lower braking means low gain, higher braking means high gain.

 

Your brake controller is only applying braking from the trailer/camper WHEN you are applying PHYSICAL braking within the truck... it is NOT going to apply any trailer/camper brakes when you are simply REGENing down hills, or when you simply come off of the GO pedal... so, the truck is able to then capture MORE Regen because of the added weight and inertia, otherwise.

 

This makes a lot of sense but how do you know it to be true that the trailer brake is only applied when the truck friction brake is activated?

 

I haven't towed with mine except with a trailer without brakes, but here's my logic - the trailer brake controller should only engage the trailer's brakes when the driver pushes on the brake pedal. Any regeneration that takes place without pushing on that pedal shouldn't do anything to the trailer's brakes. When you push on the brake pedal, whether it's using regen or actual brake pads on the truck should be irrelevant, the trailer brake controller should engage. Of course, no one in their right mind should be using 1 pedal driving with a trailer attached IMO.

If that's not the way it works, I'd be shocked.

 

I hope you were not implying using the trailer mass to push the EV tow vehicle. The simple cost and complexity would make it marginal. Safety makes it a non-starter. I would invest in more solar before that.

 

Since pulling a loaded trailer means more momentum and momentum is what allows regen to happen, how can regen be maximized leading to overall better range?

 

So far two (2) great ideas have come out of this discussion.
1) A new tow mode that keeps a selectable power out put constant when towing.
2) A auto variable trailer brake gain setting.
(See descriptions above in this thread as to what these things mean.
We are not the FMC vehicle engineering department nor should we contend to know better. We are just every day users with towing experience that most of us have had and are just ideas that may make sense to be explored for higher efficiency in future product releases.