Charging While Driving?

Bob Anderson

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I haven't seen this topic come up before, but very possible I've missed it. Doesn't it seem like all EV trucks are missing a big opportunity to allow a plug by the hitch for solar charging while it is being towed? Elon mentioned solar on tonneau cover w/ solar could add 30-40mile per day. Imagine what energy a much larger RV could provide. A good way to make up lost range to towing, and additionally, you don't have to connect solar once stopped. It's already connected.

Thoughts? Seems like a perfect option for a tow package.

 

Crissa

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Yes, it does seem that charging the pack while driving is a big missed opportunity.

It would have to handle voltage topping and overvoltages from using regen, though, and the number of users would be small - which is probably why it hasn't been done it.

It's been covered alot, at least early on in the forum's history, its most fervent proponent was the CybertruckTruckGuy, as such a port could be used with any energy source.



-Crissa
 

Luke42

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Yes, it does seem that charging the pack while driving is a big missed opportunity.

It would have to handle voltage topping and overvoltages from using regen, though, and the number of users would be small - which is probably why it hasn't been done it.

It's been covered alot, at least early on in the forum's history, its most fervent proponent was the CybertruckTruckGuy, as such a port could be used with any energy source.
There are more issues than that. I started my career as an IT guy, so I'm primed to think about the cabling for everything.

For those who aren't in the habit of towing travel trailers around, here is what a typical weight distribution hitch looks like:
Main_Image.jpg


Keeping in mind that everything moves all of the time and that these things get rained on, kicked around, and smacked with debris.

The first question is:
Hhow do you run a high-amperage/high-voltage electrical cable through there without abrading the insulation and while protecting it from road-damage?

The existing 7-pin connector (and the heavily protected low-voltage / low-amperage cable) is brilliant, and is the result of decades of error & trial development.

These hitches are an engineering band-aid on top of an engineering band-aid. I counted one, and it takes 10 steps to hook my truck to my camper. And, yet, the only thing I've found which might-maybe be better is the ProPride / Hensley hitch which costs around $3500 (last I checked).

The second question is:
Assuming that a new hitch design solves all of the problems, re-engineering the interfaces on an established and tested tech-stack is a big deal. It's doable, bit it's a lot harder (and more expensive) than it looks -- because the installed base of these things is huge. Given that the installed base of the bad old hitches is so big, how do you beat the economic challenges of rolling out a new interface? How are you going to sell more improved hitches than ProPride does?

If you walk up to the existing trailer hitch and smack it with a tree branch, it will probably be OK afterwards. How do you get that level of durability out of a PV panel connection? It's harder than it looks.
 

Crissa

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The first question is:
Hhow do you run a high-amperage/high-voltage electrical cable through there without abrading the insulation and while protecting it from road-damage?
The same way you run a cable to a charging station. You route it away from the hitch. It needs enough slack so it can turn and some guides to keep it in its path, and a minor weight loop or spring loop to pull up the slack. These are off the shelf things. Coil cable could also work; none are sold currently but you can heat-form some with a hair dryer.

The existing 7-pin connector (and the heavily protected low-voltage / low-amperage cable) is brilliant, and is the result of decades of error & trial development.
..And basically irrelevant to a charging cable.

Cables already have been designed to deal with being slapped, dropped, kicked, run over...

It's not a new issue. The connection is the easy part. The hard part is making sure that overvoltage doesn't happen on the supply side or the truck side. Every time you hit the brakes, regen will pop on and cut into the head space that your solar can feed into. That will need to be balanced. Or worse, shunted into heat so that it doesn't overheat (ala those Mach-Es going downhill).

-Crissa
 
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Bob Anderson

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The same way you run a cable to a charging station. You route it away from the hitch. It needs enough slack so it can turn and some guides to keep it in its path, and a minor weight loop or spring loop to pull up the slack. These are off the shelf things. Coil cable could also work; none are sold currently but you can heat-form some with a hair dryer.


..And basically irrelevant to a charging cable.

Cables already have been designed to deal with being slapped, dropped, kicked, run over...

It's not a new issue. The connection is the easy part. The hard part is making sure that overvoltage doesn't happen on the supply side or the truck side. Every time you hit the brakes, regen will pop on and cut into the head space that your solar can feed into. That will need to be balanced. Or worse, shunted into heat so that it doesn't overheat (ala those Mach-Es going downhill).

-Crissa
How does Aptera prevent overcharging with their solar cells? Regen braking is simple enough, just use 100% brakes until enough battery is depleted.
 


Crissa

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How does Aptera prevent overcharging with their solar cells? Regen braking is simple enough, just use 100% brakes until enough battery is depleted.
They have an integrated and programmed controller. They cannot be swapped or upgraded from stock.

And yes, mixing more brakes in is one way. Porsche supposedly used capacitor and resistor banks to bleed off the excess energy so braking would remain the same. You you need to solve both ends of the circuit - where does the extra power go, since you have only limited control over the generation of it. (The motor will produce some regen, no matter what. The solar panels will continue producing some, no matter what, etc.)

-Crissa
 

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The same way you run a cable to a charging station. You route it away from the hitch. It needs enough slack so it can turn and some guides to keep it in its path, and a minor weight loop or spring loop to pull up the slack. These are off the shelf things. Coil cable could also work; none are sold currently but you can heat-form some with a hair dryer.
I can't visualize what you're suggesting here.

The hitch allows rotation in all three directions, but prevents translation in all three directions.

So you attach the charging port to the center of the tailgate and apply tension from the trailer?

Or with bungees and some trailer-side guides to the chargeport on the side?


..And basically irrelevant to a charging cable.

Cables already have been designed to deal with being slapped, dropped, kicked, run over...

It's not a new issue. The connection is the easy part. The hard part is making sure that overvoltage doesn't happen on the supply side or the truck side. Every time you hit the brakes, regen will pop on and cut into the head space that your solar can feed into. That will need to be balanced. Or worse, shunted into heat so that it doesn't overheat (ala those Mach-Es going downhill).
The 7-pin trailer connector (and the associated cable) is relevant because it's a working solution to a lot of the mechanical, sociological, and electrical issues present in routing electrical cabling through a trailer hitch.

It's not the same thing, but spending some time with it will teach you what the mechanical and sociological requirements are for a high-power charging cable.

What you'll find when you look closely at one is that it's mostly rubber-that-protects-the-wires. This cable is a great model of the mechanical requirements.

As for the electrical requirements, scaling this style of wire up to a higher voltage and higher amperage while still being as tough and flexible as the 7-pin wire strikes me as a full-blown engineering challenge in and of itself.

For the sociological requirements, you'll find that nearly every large vehicle designed with towing in mind incorporates the 7-pin trailer connector. (There is also a standard 4-pin trailer connector is for trailers without brakes, and adapters are readily available.) There are huge benefits to standardization here, because trailers can easily be swapped between tow-vehicles (assuming similar capacities). If you make trailers, you don't have to design a different trailer for your Ford customers than you do for your Chevy customers -- and if you have to design Tesla-specific trailers, most trailer-makers will tell us they don't want our business.

Engineering your way around these problems is definitely possible!!!! It's just just a lot harder and more expensive than it first appears. I don't want to discourage anyone from engineering their way out of this, I just want to point out that the work required is nontrivial.
 
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cvalue13

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Elon mentioned solar on tonneau cover w/ solar could add 30-40mile per day. Imagine what energy a much larger RV could provide.
lets say a large RV could provide 4X a tonneau, and let’s take EM’s estimate as the per-tonneau generation as correct, then we arrive at 120-160 mi/day, or 5-6.5mi/hr.

I think we have to also assume that EM’s estimate was for moving a CT, not moving a CT while towing an RV large enough for 4X the panels. So that 5-6.5mi/hr for a CT is easily halfed (if not in thirds) for towing such an RV, bringing us to 2.5-3.25 mi/hr.

Even if all this guesstimating is off by a few orders of magnitude, this starts to sound like a lot of kit, for what amounts to not a lot of return, for a very few customers.

Especially when we consider that the relative alternative exists and provides a decent amount of capability already: RV’s with their own stand-alone solae that can re-charge a car (albeit weakly) when not driving.

B00E9E82-663F-473A-B1FB-D2622BEC8F04.jpeg
 


Luke42

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I don't know why, cable routing is a simple solved problem.

3099DDCB-405C-4C5D-AE3D-4AEF92720508.jpeg


-Crissa
Those are hollow hoses and very light.

The type of wire coming off of a decent-sized PV array is probably going to look a lot like this heavyweight 50-amp 6-gage wire running at whatever voltage the PV array produces.

Making this work is far from impossible, but some real engineering is going to be required to make it happen.
 
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Bob Anderson

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lets say a large RV could provide 4X a tonneau, and let’s take EM’s estimate as the per-tonneau generation as correct, then we arrive at 120-160 mi/day, or 5-6.5mi/hr.

I think we have to also assume that EM’s estimate was for moving a CT, not moving a CT while towing an RV large enough for 4X the panels. So that 5-6.5mi/hr for a CT is easily halfed (if not in thirds) for towing such an RV, bringing us to 2.5-3.25 mi/hr.

Even if all this guesstimating is off by a few orders of magnitude, this starts to sound like a lot of kit, for what amounts to not a lot of return, for a very few customers.

Especially when we consider that the relative alternative exists and provides a decent amount of capability already: RV’s with their own stand-alone solae that can re-charge a car (albeit weakly) when not driving.

B00E9E82-663F-473A-B1FB-D2622BEC8F04.jpeg
The longest distance route I would use this feature on is 10hrs, using your lowest estimate of 2.5miles/hr X 10hrs, that's 25 miles of TOWING range, which I'd definitely take.

Other benefits:
1. I don't need to have a large battery in trailer that isn't being used 95% of the year. I'll take that money and spend it on a bigger battery for CT.
2. If you're at a campground, you now can just power your CT, not your camper too.
 

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The longest distance route I would use this feature on is 10hrs, using your lowest estimate of 2.5miles/hr X 10hrs, that's 25 miles of TOWING range, which I'd definitely take.
of course a free 25 miles, who wouldn’t!

whether I’d “take” it, though, depends on the price, for starters.

what do you think you’d be willing pay for this kit?

 

 
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