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Comment by patall | Hacker News Reader

I am actually more wondering why we do not see battery trailers. Imagine a two wheel, 500 lbs trailer that you pull for the next 30 miles between two 1 minute stops on the highway that recharges your cars battery within those 30 miles. I know there are prototypes, but something seems to stop it from becoming large scale. Inefficient? To much overhead? Can normal drivers not be trusted with a 500 lbs trailer? I would like to know...

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I don't think there'd be much actual time savings. Every time I get off the highway to get gas (which means slowing down to exit, stopping at the bottom on the exit ramp, driving to the gas station, pumping gas, getting back on the highway, etc), it ends up being close to a 15 minute stop. I'd be surprised if you can pull off, hook up a battery trailer (and pay for it), then get back on the highway in a few minutes.

Might as well just stop in for a 20 minute charge at a DC fast charger, many cars can do an 80% charge in 20 minutes.

This actually sounds doable if the battery charging trailer is self driving (and self docking). You would lose only minimal time slowing down for the docking/undocking. Easier to test on select pieces of highway with predictable self driving conditions. And the highway gives you space and time for charging, when you need it most for long trips.

We're still far from having self-driving cars, I don't think we'll have self-driving battery trailers running around the highways anytime soon. And you've just more than doubled the cost of these battery trailers by putting motors and control systems in them.

My gas powered car gets around 300 miles of range before the fuel light comes on and I need to make a 10 or 15 minute stop to refuel. I think I could survive with an EV that gets 250 miles of range between charges (300 mile rated range, assuming 80% charge) before needing a 20 minute charge stop, I need to stop and stretch my legs, eat, or use the restroom more often than that.

Too much overhead and DC fast charger networks are already approaching parity with the speed you could make that work. Trailers add another set of wheels to the ground, too, which is a failure point. Might as well just put it on the roof or something instead.

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