Show HN: lapetitejort goes hiking, discovers perpetual motion
I would imagine that at best, you could maybe match the range. If there's any scenario where going up and down a hill would yield more range than driving flat, I'd be very interested in how/why.
Cruising on level terrain is a mediocre load on the traction system to offset the rolling and aerodynamic friction. Climbing a steep grade at the same speed will increase the load significantly, but that extra kinetic output energy is being stored as gravitational potential energy rather than lost like the baseline cruising load. Then, when you descend the mountain on the other side, you recover that gravitational energy to offset the rolling and aerodynamic friction. You want to be "falling" down the mountain grade at your terminal velocity where no braking and no traction force is required to maintain your cruising speed. It will not work well for winding descents where you need to brake for turns.
I've seen this work with turbocharged ICE cars with elevation gains of 4k foot or more and hundreds of miles distance. I've repeated on many trips to prove to me that it isn't simply a fluke (such as extreme headwind or tailwind). Going over a pass yields me a better trip MPG than covering the same several hundred miles on relatively flat ground.
I could see this benefit for a hybrid car too, since I believe they mostly handle highway cruise on ICE power. However, it seems unlikely for a BEV car unless there is something about battery and power electronics that I do not understand, that would give them a significant efficiency boost at high power.
Suppose you're going to make a 100 mile (160 km) trip. You have two possible routes. One is a straight shot on level ground. The other is straight, too, but it takes you up a 10% grade for the first 10 miles (gaining 1 mile in altitude), then you continue on level ground for 80 miles, and then you descend a matching 10% grade at the end.
It seems like the 80 miles of cruising on level ground at high altitude would use less battery than 80 miles of cruising at sea level (if the speeds are the same).
There will be some losses due to climbing and descending. Maybe climbing and descending is a little less efficient. Also, you're definitely traveling a very slightly longer distance. But those losses might be made up for spending the bulk of your trip in thinner air.
No. Climbing the hill the car uses extra energy (compared to a flat road) because its fighting gravity. On the way back down the hill regen will recover some of that gravity-fighting energy but nowhere near all of it.
https://phys.org/news/2017-09-e-dumper-world-largest-electri...
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
It’s actually very interesting to me that while driving that car, I developed a sort of feel for how trading potential and kinetic energy affected my available range, and I had an imaginary boundary drawn in my head that defined all the places where I’d be able to make it home “for free” that was kind of like a topo map. In particular, if I managed to crest the hill where Canlis sits on highway 99, I knew that despite all the ups and downs in between me and home, I’d be able to make it there without having to fire up the gas engine. :D
Why not design them to be aerodynamic for headwinds, and maximize wind-resistance for tailwinds? I wonder how much energy would be gained.
I hope the prosecutor has enough leverage with the court! Justice truly is blind!
New EV users often forget that unlike 'gallons of gasoline' or 'kWh', 'estimated miles of travel' are not a true unit of energy.