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you can tow charge an electric car with another car or truck

by useful 5y ago

rampant_ai 5y ago
Charging efficiency isn't 100%, so you'd have to tow it further than the range you need. Seems like it'd make more sense to just tow it to a charger.
- tantony 5y ago
  > Charging efficiency isn't 100%, so you'd have to tow it further than the range you need That's not how it works. You basically get 5 mpg or less on the truck, while the car charges at significantly higher rates than the speed of the truck (in mph), because the car is more efficient at using the energy. https://insideevs.com/news/514727/tesla-towing-70mph-fast-charging/ https://insideevs.com/news/514727/tesla-towing-70mph-fast-ch... Towing at 70mph in the above example was charging the car at 65 kW. That's equivalent to ~260-270 mi/hr of charging rate assuming 250Wh/mi.
  - seabrookmx 5y ago
    The comment you replied to is still correct though. Distance wise, tow charging makes no sense. Energy wise, maybe it does.
    - tantony 5y ago
      If it makes sense energy wise, it makes sense distance wise too. If the EV can go 4 miles for every one mile towed, then why would it not make sense?
      - seabrookmx 5y ago
        Ah I think I was tripped up by the same thing as the top commenter. This sounds like it violates the law of conservation of energy. The key here is that when towing (as opposed to going downhill) you can put much more energy into the motor generators per mile than is required to drive a mile. Due to charge/discharge losses, for your example this would have to be > 4x the amount. This obviously assumes the EV can regen at high sustained rates and you have a powerful tow vehicle. So yes, you're right. The energy/distance argument should be one and the same.
burntwater 5y ago
I looked into this a few weeks ago while exploring purchasing an electric car, and from what I could find "tow charging" was experimented with but has basically been given up on. The expectation is that if you lose power, you will need a flatbed truck to cart the car to a charging station.
Ekaros 5y ago
How do you order an other car or a truck if you can't make phone calls?

you can tow charge an electric car with another car or truck

by useful 5y ago

you can tow charge an electric car with another car or truck

Charging efficiency isn't 100%, so you'd have to tow it further than the range you need. Seems like it'd make more sense to just tow it to a charger.

tantony 5y ago
> Charging efficiency isn't 100%, so you'd have to tow it further than the range you need That's not how it works. You basically get 5 mpg or less on the truck, while the car charges at significantly higher rates than the speed of the truck (in mph), because the car is more efficient at using the energy. https://insideevs.com/news/514727/tesla-towing-70mph-fast-charging/ https://insideevs.com/news/514727/tesla-towing-70mph-fast-ch... Towing at 70mph in the above example was charging the car at 65 kW. That's equivalent to ~260-270 mi/hr of charging rate assuming 250Wh/mi.
- seabrookmx 5y ago
  The comment you replied to is still correct though. Distance wise, tow charging makes no sense. Energy wise, maybe it does.
  - tantony 5y ago
    If it makes sense energy wise, it makes sense distance wise too. If the EV can go 4 miles for every one mile towed, then why would it not make sense?
    - seabrookmx 5y ago
      Ah I think I was tripped up by the same thing as the top commenter. This sounds like it violates the law of conservation of energy. The key here is that when towing (as opposed to going downhill) you can put much more energy into the motor generators per mile than is required to drive a mile. Due to charge/discharge losses, for your example this would have to be > 4x the amount. This obviously assumes the EV can regen at high sustained rates and you have a powerful tow vehicle. So yes, you're right. The energy/distance argument should be one and the same.

burntwater 5y ago

I looked into this a few weeks ago while exploring purchasing an electric car, and from what I could find "tow charging" was experimented with but has basically been given up on. The expectation is that if you lose power, you will need a flatbed truck to cart the car to a charging station.

Ekaros 5y ago

How do you order an other car or a truck if you can't make phone calls?