EV Towing

Solar panels are getting more efficient every year.  Lining the top of an enclosed trailer with them and wiring it to charge the tow pig's battery would help a bit - not much, but every bit helps.  Keith mentioned a situation where you could get 50 miles over a race weekend.  50 is a good start.  Somehow adding regenerative braking to the trailer so that it helped charge the tow pig, not a battery on the trailer (adding a battery to the trailer would add a lot of weight and cost, not that regenerative braking would cost pennies) could all add up to making a difference.  Towing across the country, probably not.  But towing 200 miles away to a race track, parking there for two days, then towing home, absolutely.  

So the hybrid trailer idea is being done in the locomotive world.  In the past, they would use their motors to brake a train, dumping all of that energy into a massive resistor pile.  Now that energy goes into a big box in between train engines.  Including it's tractive effort ability, trains can go up and down passes with a lot less fuel.

But adding any gas generator for range extension is just a different version of a hybrid.  Which I think can be gotten in an F150 these days.

BTW, I find it curious that people don't think that there's braking regeneration on these trucks.  That was a hallmark of the first hybrids, and is certainly on all EVs.  Adding two axles via the trailer would be nice, but it doesn't do much braking compared to the driving vehicle.

My 100W panel is right around 6 square feet in area. So figure 2.6 kW on the roof of a 20x8 trailer. Let's be kind and assume that we can burn 500 Wh when towing a trailer, that means the panels on the roof can add 5 miles of range every hour. That's assuming 100% efficiency and perfect output, so this is better than best case.

Efficiency drops way off when you're not facing straight at the sun. Your panel-covered trailer could only actually have direct sunlight on three sides at most, and none of them would be at the best angle. So you're not going to get anywhere near 50% of the potential max output.

I spent some time with a small panel and a voltmeter a while back. It's actually really interesting to play with angles and see how much even a small shadow on one corner of the panel screws with output.

Like I said, it will have some benefit. But is it enough to be worthwhile? Likely not.

If you want to make a trailer aerodynamic, don't spend your time rounding the leading edges. Pay attention to the door and the lower sides. Start watching semis on the interstate, you'll see some nice tweaks.

infinitenexus said:

Solar panels are getting more efficient every year.  Lining the top of an enclosed trailer with them and wiring it to charge the tow pig's battery would help a bit - not much, but every bit helps.  Keith mentioned a situation where you could get 50 miles over a race weekend.  50 is a good start.  Somehow adding regenerative braking to the trailer so that it helped charge the tow pig, not a battery on the trailer (adding a battery to the trailer would add a lot of weight and cost, not that regenerative braking would cost pennies) could all add up to making a difference.  Towing across the country, probably not.  But towing 200 miles away to a race track, parking there for two days, then towing home, absolutely.  

My example assumed you were driving one of the most efficient EVs on the road today. You're sure not getting 50 miles of range on a towing vehicle with those numbers. As codrus said, running an extension cord from a 110v socket would probably be just as effective.

I assume any EV is regenerating. I think we'd get a lot more out of pulling some energy out of the trailer brakes than we would with solar all over the box.

Diesel trucks are going to continue to be the first choice for individuals to tow long distances for a long time.

alfadriver said:

Adding two axles via the trailer would be nice, but it doesn't do much braking compared to the driving vehicle.

The ratio of braking should be about the same as the ratio of weight between the tow vehicle and trailer.  So for the kinds of enclosed race trailers we're talking about you're probably doing half the braking on the trailer axles.

FYI, there's a mining truck (in Europe, I think) that picks up a load at the mine and runs down the side of the mountain to drop it off. It then drives up empty for the next load. It captures enough energy from regen on the way down to get back up again. It's powered by the change in potential energy from the rocks it's carrying down the hill. Obviously a very specialized case but how cool is that?

Basically, it's the equivalent of having two trucks attached with a long rope and a pulley at the top. The full truck going down drags the empty truck up.

Keith Tanner said:

FYI, there's a mining truck (in Europe, I think) that picks up a load at the mine and runs down the side of the mountain to drop it off. It then drives up empty for the next load. It captures enough energy from regen on the way down to get back up again. It's powered by the change in potential energy from the rocks it's carrying down the hill. Obviously a very specialized case but how cool is that?

Basically, it's the equivalent of having two trucks attached with a long rope and a pulley at the top. The full truck going down drags the empty truck up.

I have seen that before, its pretty clever.

For some reason it reminds me of the Falkirk Wheel.  It can lift a boat up 36ft, but only has to overcome friction, because as long as the water level is the same, its perfectly balanced.

In reply to Keith Tanner :

I had an entire course in college that got into calculating angles of incidence, power drop, and solar flux. Got into seasonal effects and expectations. We did a project where we made a tracking system for a solar panel to make it follow the sun through the course of the day. I can't recall what the boost was, but it was considerable. I think we also did the calculations to elevation to compensate for season...   It was over a decade ago, still have the textbook though.

In reply to ProDarwin :

That's just wild. Can you imagine the meeting with the initial proposal? "no, wait, hear me out! I'm serious!"

to change this a bit , can you tow most EVs with a motorhome ?

Flat Tow or on a Tow dolly ?

if the electric motor is part of the rear axle does it freewheel ?

and does regenerative braking do anything when towed ?

In reply to californiamilleghia :

Rivians can be tow charged, so I assume others can too. The team on Long Way Up had to do that for one of their support rigs.

Regen involves current amounts similar to fast charging. You're shoving a lot of energy into the battery in a short time. It creates heat, the enemy of battery life. There's a reason that EV manufacturers will limit how much juice can be shoved into a battery in a given time period, so constant regen from flat towing, or traveling down grades might work for a few miles but it's not advisable for complete battery charging. At least with current tech.

STM317 said:

Regen involves current amounts similar to fast charging. You're shoving a lot of energy into the battery in a short time. It creates heat, the enemy of battery life. There's a reason that EV manufacturers will limit how much juice can be shoved into a battery in a given time period, so constant regen from flat towing, or traveling down grades might work for a few miles but it's not advisable for complete battery charging. At least with current tech.

I imagine they would just need a software tweak for that.  It would set the regen to a pretty low #, similar to a wall charger (say... 6kw), except during heavy braking when you would want the extra braking capacity anyway.

Though a bit counterproductive on the emissions standpoint, it would seem the logical range extender for long-distance towing vehicles and such would be a high-output gas/diesel auxiliary generator (with an integrated fuel tank) that can be dropped into the bed or frunk to provide power running at a most-efficient/peak rpm. Basically, turn the truck into a temporary hybrid. 

Keith Tanner said:

FYI, there's a mining truck (in Europe, I think) that picks up a load at the mine and runs down the side of the mountain to drop it off. It then drives up empty for the next load. It captures enough energy from regen on the way down to get back up again. It's powered by the change in potential energy from the rocks it's carrying down the hill. Obviously a very specialized case but how cool is that?

Basically, it's the equivalent of having two trucks attached with a long rope and a pulley at the top. The full truck going down drags the empty truck up.

That is the general idea for the space elevator.  You get out into low earth orbit by dropping an equal amount of mass down.

All you need is a material stronger than anything we have, and a way to capture matter in space for the weight down.

irish44j (Forum Supporter) said:

Though a bit counterproductive on the emissions standpoint, it would seem the logical range extender for long-distance towing vehicles and such would be a high-output gas/diesel auxiliary generator (with an integrated fuel tank) that can be dropped into the bed or frunk to provide power running at a most-efficient/peak rpm. Basically, turn the truck into a temporary hybrid. 

A high output engine isn't needed for nominal charging- it just needs to be big enough to charge more than you use in nominal use.  Most vehicles don't use 50kW constantly, so that would be more than enough.  Maybe have a 100kW gen set, so that you can add 50kW extra power to the battery output going up a hill.

Although, if you spend any time looking into the situation, generators are under 100kW.  And making virtually no emissions based on available generators is actually pretty darned easy.

For the most part, it's just some good powertrain matching given the target peak load you plan to support.  So if an F150 needs to pull 10klb up hills without slowing down- it's a pretty simple matter of physics.  Size the battery and generator around what you need to to.

Pete. (l33t FS) said:

That is the general idea for the space elevator.  You get out into low earth orbit by dropping an equal amount of mass down.

All you need is a material stronger than anything we have, and a way to capture matter in space for the weight down.

You don't even need to transfer weight down for a space elevator to make sense.  The big win is that it escapes the "tyranny of the rocket equation" by avoiding the need to accelerate all of your fuel/oxidizer/reaction mass along with you.  Instead you use an electric motor and wheels to climb the cable, so you're using the Earth itself as the reaction mass.

alfadriver said:

irish44j (Forum Supporter) said:

Though a bit counterproductive on the emissions standpoint, it would seem the logical range extender for long-distance towing vehicles and such would be a high-output gas/diesel auxiliary generator (with an integrated fuel tank) that can be dropped into the bed or frunk to provide power running at a most-efficient/peak rpm. Basically, turn the truck into a temporary hybrid. 

A high output engine isn't needed for nominal charging- it just needs to be big enough to charge more than you use in nominal use.  Most vehicles don't use 50kW constantly, so that would be more than enough.  Maybe have a 100kW gen set, so that you can add 50kW extra power to the battery output going up a hill.

Although, if you spend any time looking into the situation, generators are under 100kW.  And making virtually no emissions based on available generators is actually pretty darned easy.

For the most part, it's just some good powertrain matching given the target peak load you plan to support.  So if an F150 needs to pull 10klb up hills without slowing down- it's a pretty simple matter of physics.  Size the battery and generator around what you need to to.

I really just meant "high output relative to size/weight" since obviously you don't want a huge diesel genset in the bed ;)

In reply to ultraclyde :

Buy a Ford F-150 EV. 
 Towing capacity 10,000 pounds !!!  
 Price $39,974  with tax incentives in the $30,000 range!!!   
     Cargo capacity?  2000 pounds.  
Range std model 230 miles. (300 available ) 

EV trucks for towing will likely depend a lot on how it's used.  I tend to look at EVs from the "I don't want to buy gas/deisel" reason, which influences how I imagine an EV being used.

I could see landscapers using EV trucks since they typically don't have to tow their trailers very far each day and therefore range is less of a concern.  Drive to the jobs, then back to the yard, plug in, and be ready for the next day - not having to think about whether the daily job route passes a fueling station.  The idea of an EV trailer has some merit there as well, especially if the tech gets to the point where EV landscape equipment could go entirely gas-less using the trailer battery to recharge the equipment batteries.

The trick would be balancing the up-front costs vs. the time saved not having to stop at a gas station every day to refuel along with the reduced maintenance that battery equipment typically has vs. gas equipment. 

In reply to Ian F (Forum Supporter) :

Have you seen the start ups on Fords F150 EV ?   $39,974. And there is a federal $7500 tax break.  
   4WD 439 hp. 10,000 towing. 2,000 load, 230 mile range ( optional 300 ) 41 min recharge time.  

   Since that's about what I paid 4 years ago. Price is not going to be a issue. 
 
yes

Kind of an open question- will campgrounds allow the trucks to recharge?  The biggest power supply for campgrounds is 50A at 120V, so you would get the leftovers that isn't being used for your trailer.  You'd need a smarter distribution, but without any other loads, that would be 600W.  Not sure how long it would take to fully charge an F150 at 600W.

Given the costs of having many full charging stations, some campgrounds may upgrade- but they will certainly pass on the expense of all of those chargers to all of their customers.

Someone mentioned aero way up thread.  This is huge once moving and something that would be so easy to improve on with modern trucks.  Can we please get away from this stupid trend of needing a berkeleying ladder to reach the bed of trucks.  Look at the bed height on an 80's/90's truck compared to today.  My daughter was moving recently and borrowed an F150 to move some large furniture.  The job would have been about a billion times easier if the truck bed would have been 8-12" closer to the ground.  Imagine the aero improvement of cutting a foot of (completely useless except for dick swinging) height of the whole rig.

In reply to alfadriver :

Who knows.  That's sort of a chicken-egg question.  Camp gounds will invest in charging infrastructure when they start getting asked about it. And the in the same way a 50A parking spot costs more than a 30A parking spot, they will likely charge a premium for it.  I can imagine it will also depend on the rig in question.  If it would normally take a 30A connection for the house systems, but could take a 50A connection to recharge the EV batteries, much of that could (should?) be integrated into the EV RV.  Plug into the 50A connection with a regular cord and the onboard system distributes the power as needed.  There are already battery systems that can do this sort of power distribution, allowing an RV that would normal take a 50A plug to run on 30A, using the batteries to take up the load during high-peak loads, and recharging the batteries during low-peak periods.

In reply to Adrian_Thompson (Forum Supporter) :

Load deck height is one reason I like vans over pick-up trucks for most tasks. 

In reply to Adrian_Thompson (Forum Supporter) :

I keep hitting thumbs-up but it only registered one.