Comment by bryanlarsen
4 days ago
Electric engines are very efficient; aerodynamic drag is by far the biggest source of efficiency loss. The most efficient traversal for a fixed time interval is fast acceleration / deceleration with a reduced top speed. OTOH the most efficient for same time interval for a gas vehicle would be a slightly higher top speed but lower acceleration / deceleration.
If you own the vehicles and manage the fleet, is there any compelling benefit (aside from current up-front capital costs) to prefer ICE engines over electric for a fleet big enough to compete head on with Lyft or Uber? Even the additional uptime per vehicle thanks to lower ongoing maintenance is a compelling enough reason to jump for EVs.
Charging so many cars. With a fleet of ICE cars any old gravel lot by the airport works. With a fleet of EVs you're going to need depots with upgraded service drops, chargers strung everywhere that need to be maintained, and to pay somebody to come unplug them every morning.
Closer to guaranteed range. With a fleet of EVs it's possible that a frosty morning or long weekend where everybody wants a trip out of town might drain them all in sync in a way ICEs would be less impacted by.
And then at the intersection of these two: flexibility recovering from some incident. Assume some "night crew didn't refuel" situation, sending out a fleet of ICE cars half empty and planning to refuel them all between trips is fairly simple, but sending out a bunch of half empty EVs and trying to somehow add an unplanned recharge midday is at best logistically more difficult, and at worst, causes other cascading problems.
> aerodynamic drag is by far the biggest source of efficiency loss.
Rolling resistance is a bigger source of loss under 30 mph.
> The most efficient traversal for a fixed time interval is fast acceleration / deceleration with a reduced top speed
Wouldn't it be increasing speed for half the trip and decreasing it for the other half?
Why would fast acceleration and deceleration be more efficient? When you drive an electric car it’s usually the opposite: fast acceleration drains the battery fast, and slow deceleration allows for better regenerative braking without having to use the actual brakes.
Because it lets you use a lower top speed to maintain the same trip time. If you have an EV, you know just how much a few extra mph drops the range.
And obviously it's within reason -- if you're shredding tires, you're wasting a lot of energy doing that.
In the context of ride sharing, though, it's likely that you spend most of the time in most rides going much slower than the ideal top speed. Most ride shares are heavily biased towards city driving with frequent stops and relatively low speed limits.
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