Infinite Range Cheat?

[Jumacao]

If you have two EVs which are both capable of towing, could you theoretically switch off flat towing between the two and drive across the US without stopping to charge?

Ingoing assumptions:
- You'll lose about 50% range when towing with an EV
- Flat towing EVs have, in some cases, resulted in charging speeds equivalent to a DC fast charger when using regenerative braking as a charging method

If both of those assumptions are true, then you could flat tow one vehicle for 150 miles while the other one charges using its regenerative brakes (which shouldn't take more than 40-50 miles at 70 mph), then switch off.

This seems like something a Youtuber would have done by now if it were possible, so I think I'm missing some part of the equation. Can anyone think of a reason why this wouldn't work?

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[Donald Stanfield]

Using regenerative brakes uses way more energy on the towing car than simply pulling something in neutral. What you are suggesting is a perpetual motion machine which, as far as we know, is impossible. Energy is always lost due to friction and heat no matter what you do.

 

[FLTANK]

I think you’re forgetting that any significant level of regen while towing is basically towing a trailer with the brakes locked on so your range probably drops by 95% in the tow vehicle. Sorry to say we will have to keep searching for an infinite persistence energy source.

 

[Dark-Fx]

wat

 

[Foobar]

Even if EV's were 100% efficient, that wouldn't work because your tow vehicle is consuming more energy than your regen vehicle is recovering.

Add in the inefficiencies involved and it all goes downhill from there.

At the end of the day, the first law of thermodynamics can't be violated.

 

[Yellow Buddy]

If you have two EVs which are both capable of towing, could you theoretically switch off flat towing between the two and drive across the US without stopping to charge?

Ingoing assumptions:
- You'll lose about 50% range when towing with an EV
- Flat towing EVs have, in some cases, resulted in charging speeds equivalent to a DC fast charger when using regenerative braking as a charging method

If both of those assumptions are true, then you could flat tow one vehicle for 150 miles while the other one charges using its regenerative brakes (which shouldn't take more than 40-50 miles at 70 mph), then switch off.

This seems like something a Youtuber would have done by now if it were possible, so I think I'm missing some part of the equation. Can anyone think of a reason why this wouldn't work?

I made a couple of snarky comments but decided to modify the post..hopefully this helps.

The way the truck works is there are onboard inverters. Inverters are not 100% efficient. I don't know what the efficiency rates of the two EVs is, but you're going to lose energy in the conversion from motion to electricity. (For comparison my solar inverters experience a 15-20% loss)

That alone will guarantee you won't be able to go indefinitely. That's not even going into friction and other energy losses. To oversimplify it, it's a bit like saying if you plug the mobile charger into the bed outlet, shouldn't you be able to drive forever...

That said, I did have to flat tow my Model S when the charger unit went. First, it is NOT a fun experience. Doing it at speed is nerve wracking. We found it best to flat tow it locally uphill a long stretch of road and then drive/roll her downhill at highway speeds unhooked to regen back as much power as possible. We did not want to flat tow her for an extended period of time.

 

[COdogman]

 

[ironpig]

If you have two EVs which are both capable of towing, could you theoretically switch off flat towing between the two and drive across the US without stopping to charge?

Ingoing assumptions:
- You'll lose about 50% range when towing with an EV
- Flat towing EVs have, in some cases, resulted in charging speeds equivalent to a DC fast charger when using regenerative braking as a charging method

If both of those assumptions are true, then you could flat tow one vehicle for 150 miles while the other one charges using its regenerative brakes (which shouldn't take more than 40-50 miles at 70 mph), then switch off.

This seems like something a Youtuber would have done by now if it were possible, so I think I'm missing some part of the equation. Can anyone think of a reason why this wouldn't work?

Yeah as others have said, you wouldn't make it very far towing a 7000 lb truck with its brakes on.

 

[HeyEllwood]

This is some real high guy post here.

But I like it.

 

[Dark-Fx]

Back when DC charging was still basically unviable for long trips, I had actually considered just parking another Bolt EV 150 miles away on L2 charging so we could just swap cars on a trip. Would still be quicker than stopping for a recharge.

 

[Foobar]

Back when DC charging was still basically unviable for long trips, I had actually considered just parking another Bolt EV 150 miles away on L2 charging so we could just swap cars on a trip. Would still be quicker than stopping for a recharge.

If batteries could be standardized, one method of allowing EV's to get back on the road quickly would be to have stations that stock fully charged batteries. You drive in, unload your spent batteries, swap in fully charged ones, and get back on the road while your spent batteries get charged up for someone else to swap in. You were just a bit ahead of your time!

 

[COdogman]

Back when DC charging was still basically unviable for long trips, I had actually considered just parking another Bolt EV 150 miles away on L2 charging so we could just swap cars on a trip. Would still be quicker than stopping for a recharge.

That’s not a bad idea. When you think how far we’ve come since then it’s pretty amazing. Still a long way to go in many parts of the country but progress is accelerating.

 

[Dark-Fx]

If batteries could be standardized, one method of allowing EV's to get back on the road quickly would be to have stations that stock fully charged batteries. You drive in, unload your spent batteries, swap in fully charged ones, and get back on the road while your spent batteries get charged up for someone else to swap in. You were just a bit ahead of your time!

I like that in theory but I don't want someone else's abused battery. Abuse could be anything from charging to 100% or running to 0% regularly, or actual physical damage to the pack from running over shit.

 

[Foobar]

I like that in theory but I don't want someone else's abused battery. Abuse could be anything from charging to 100% or running to 0% regularly, or actual physical damage to the pack from running over shit.

Yeah, the technology isn't quite there yet, but I could see these types of batteries eventually having on-board diagnostics and monitoring gear that would let you know that they're operating at optimum and safe levels and are untampered/uncompromised.

 

[Autolycus]

If it sounds too good to be true, it is. The OP has described what some call a "perpetual motion machine of the third kind."

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