Can You Flat Tow EVs to Recharge Them? Yes, but There Are Asterisks

[RV_]

EVs may become the ultimate Toad for RVs. I had never thought about towing an EV four down and charging it at the same time, let alone in reverse while driving forward. Apparently the EV manufacturers are making that happen, especially Rivian and Ford. Almost free after you subtract the extra fuel the tow vehicle uses with the added resistance? Don't know yet. I did not even know the Rivian I have on order can be charged while in reverse? An interesting article indeed.

From MOTORTREND Oct 2021

Excerpt:

"At What Rate Does Flat-Tow Charging Occur?

Ford reckoned its Mustang Mach-E or F-150 Lightning will generate at least 9.2 kW at reasonably low speed. Lucid had plenty of experience flat towing its Air sedan prototypes during extensive durability and development drives that sometimes saw the vehicles exceeding their impressive range nowhere near a charger (often at durability-test tracks with no chargers). Lucid claimed that when towed in the high-regen setting at 20 to 30 mph, the car should generate power at a rate of 100 kW; while being towed by a strong support truck at 60 to 70 mph in max regen, Lucid saw charging rates of up to 200 kW. Charging a Rivian with the gear selector in reverse purportedly delivers rates akin to a DC fast charger. Note that on the "Warped Perception" YouTube channel, a Tesla Model S (which comes with robust tow hooks) was flat towed behind a Mercedes-AMG E55 at 70 mph and reported a 65-kW rate, while the AMG earned 5 mpg.

Rivian may have given this the most thought, as its vehicles are inherently more likely to run out of juice farther from help. For that reason, the company makes an additional, higher regenerative braking level available: engage reverse while towing the truck forward.

Ford Patent: Battery Charging by Towed Regenerative Braking

Palmer was evidently not involved with the application for Ford Global Technologies LLC's patent US2021197673A1, published July 1, 2021, which describes a system for flat towing (via rigid connection, not rope) where an EV that's running low can request a tow charge and even potentially couple itself to and decouple itself from the tow vehicle while in motion. Now that raises safety concerns with us."

Wow! More in the article here:

https://www.motortrend.com/features/how-to-flat-tow-recharge-electric-vehicles/

 

[Chalkie]

And then there is this But as of now, there do not appear to be ANY all-electric vehicles that are capable of being flat-towed, four wheels down which is a newer article where Rivian has withdrawn its claim of four down towing. And not a single one to be found here  Roadmaster Dinghy Towing Guides.

[RV_]

 

12 hours ago, Chalkie said:

And then there is this But as of now, there do not appear to be ANY all-electric vehicles that are capable of being flat-towed, four wheels down which is a newer article where Rivian has withdrawn its claim of four down towing. And not a single one to be found here  Roadmaster Dinghy Towing Guide

Gary,

Your tow guide stopped at 2020 and it is now 2022. I could not find one more current. Is there one? I knew I could not tow the Y except on a trailer if then. From your link:

From your first RVGEEKS article:

This next is from your RVGEEKs link and everyone thought that the Rivian could be flat towed until very recently. This was above the part you quoted. The update you posted was from April 2022.

Excerpt:

"Are There ANY Electric Vehicles That Can Be Flat Towed Behind an RV?

As it turns out, we heard from Rivian directly some time back that their all-electric Rivian R1T (their pickup truck) and the Rivian R1S (their SUV) CAN be flat towed behind an RV. These two electric vehicles from Rivian are built on the same platform."

Your link: https://www.thervgeeks.com/can-electric-vehicles-be-flat-towed/#:~:text=But as of now%2C there,-towed%2C four wheels down.

The entire MOTORTREND article thought so too.

Let's go over my first paragraph with me bolding all the words that mean it is not now but is in development and may be in our RV future. Bold added just now

"EVs may become the ultimate Toad for RVs. I had never thought about towing an EV four down and charging it at the same time, let alone in reverse while driving forward. Apparently the EV manufacturers are making that happen, especially Rivian and Ford. Almost free after you subtract the extra fuel the tow vehicle uses with the added resistance? Don't know yet. I did not even know the Rivian I have on order can be charged while in reverse? An interesting article indeed. "

Now if I said is ready to be towed and charged instead of may become as in the future since the article was quite clear the charge while towing is in development not already available. Are making it happen is not have made it happen. Don't know yet is because as we can clearly read in my post and the sources I provided clearly state it is all in development.

As far as Rivian I was interested not concerned as I like to have facts not opinions or quoting only cherry picked parts:

"Cherry picking may be committed intentionally or unintentionally."

https://en.wikipedia.org/wiki/Cherry_picking

Every source was only half right about Rivian being able to tow the Rivian four down and charge. It actually can be towed to charge and in reverse! But only in emergency. See I like knowing the facts not opinions so as a customer with Rivian on order I called and asked them to answer the question of an it be towed four down and can it charge four down. I was surprised it can and can charge in reverse going forward it seems which makes little sense to me. So in the interest in being accurate here is the email I asked them to send me answering those questions:

<customerservice@rivian.com>

Hi Derek,

Thanks for taking the time to contact us. Here is a detailed explanation regarding the Flat Towing/Tow Charge question you had. 

Aside from tow charging, Rivian vehicles are not flat towable

Tow charging is an emergency recovery behavior. Basically, you've run out of charge somewhere remote and are using a tow vehicle to pull the Rivian forward to add charge back to its battery.

This is accomplished by towing the Rivian behind a tow vehicle with both vehicles facing the same direction. The tow vehicle drives forward while the driver in the Rivian puts the Rivian into neutral or reverse to resist that forward motion (but if in reverse, the Rivian driver does not accelerate so hard that it overpowers the forward motion that the tow vehicle is creating).

In short, we recommend using a Flatbed Trailer. Flat towing at 3mph or less. Tow charging: We wouldn't recommend this over long distances because (1) it'd be like driving with brakes permanently applied to the tow vehicle and (2) it could damage the inverters of the vehicle. 

The important thing to note here is that tow charging requires active drivers in both vehicles and is more about adding energy back into the Rivian than transporting the Rivian across long distances

I appreciate your support, and if there are any details I can provide, I'm always happy to follow up as well. 

Stay curious,
Danny
Weekdays: 7 AM-8 PM (CST)
Weekends: 10:30 AM-7 PM (CST)

I hope that factory source info is helpful.

 

Safe travels!

Edited June 28, 2022 by RV_

[Dutch_12078]

Charging while going forward with the selector set to reverse might make more sense when you consider that a most DC electric motors can become a generator when spun in reverse by an external force.

[rickeieio]

While this thought process is entertaining, the whole notion of charging while towing is ignoring basic physics.  Frictional losses alone would more than negate any charging achieved.  Not to mention things like fuel, drive line,  and additional tire wear (tow vehicle needs to pull harder and car is resisting).  Towing a Prius would make a lot more sense.

Edited June 28, 2022 by rickeieio

[Dutch_12078]

27 minutes ago, rickeieio said:

While this thought process is entertaining, the whole notion of charging while towing is ignoring basic physics.  Frictional losses alone would more than negate any charging achieved.  Not to mention things like fuel, drive line,  and additional tire wear (tow vehicle needs to pull harder and car is resisting).  Towing a Prius would make a lot more sense.

Did you read Rivian's response to Derek? They clearly say the procedure is for emergency charging only.

[rickeieio]

24 minutes ago, Dutch_12078 said:

Did you read Rivian's response to Derek? They clearly say the procedure is for emergency charging only.

I must admit, I did not.  I guess I pretty much repeated what they'd already pointed out.

Maybe that'll teach me to not just skim over posts......

[RV_]

Yep I have a dog in that fight because I have had a Rivian R1T on order since last year and until a post here about flat towing EVs I did not think that was possible with any AWD EV vehicle, then someone here told me the Rivian could?? I looked and like in Kirk's RVGeeks link earlier I saw they first said nor EVs could tow four down and then said the Rivian was the exception and then an update reflecting what I received from Rivian when I asked them. The RVGeeks article said Rivians were towable and then later updated it to say they found they were not but could be towed to charge in an emergency? I can respect people and groups that are willing to correct and update so their readers can get accurate info when they goof.

It pays to go to the links when provided as some with excerpt only the part they want, and ignore the part that contradicts it completely. I've made a few mistakes in my 70 years but I don't do confirmation bias.  However there are folks who intentionally obscure evade and try to correct with no knowledge. For them I'd like to say "Silence is golden. Duct tape is silver." Anon. But I am not a mean spirited person, so I don't.

[podwerkz]

It's interesting as an emergency 'jump start' but there is no 'free lunch'.

The added drag caused by the loading and drag of the toad being recharged will drop the fuel mileage of the prime mover to the point where it would be equivalent to driving up hill all the time. 

I'd rather install a large solar array on that same large RV and feed the output to batteries and an inverter dedicated to charging the EV (even if slowly) while driving, with zero (or nearly zero) added drag on the power unit up front.  

 

 

[RV_]

I think it was designed for when it was out in the boonies not with an RV. Any truck could tow it with the driver in it to follow instructions.

I thought of it like a donut spare tire. It can get you 10-25 miles or so (May be different for each one) and using it longer can cause drive-train problems especially in 4WD AWD vehicles. Not recommended for long use.

I look at what Rivian wrote to me after we had a long talk on the phone. Our conversation illuminated that for me. Anyone can look up the customer service number and ask them on the phone. I called and asked, as a customer with a deposit, if he would send me an email I could copy from and he agreed. So there was a lot more to the call than just that. I was trying to see if there was any call on how much longer before I get mine, and several other questions on things I read but wanted to confirm like 0-60 times, and I completely forgot to ask if it can really do "Tank Turns" where on one side both wheels go forward and the other side goes backward turning in it own radius. I have read it can and that it can't and that they did not know.

Like Tesla vehicles we'll know when they get production ramped up more.