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>Possible that eventually EV's will be lighter than gas cars as well. The energy density of gasoline is about 100x the energy density of batteries. Batteries c

by yodon 3y ago

>Possible that eventually EV's will be lighter than gas cars as well. The energy density of gasoline is about 100x the energy density of batteries. Batteries can have other advantages but it's pure fantasy to think batteries will beat the energy density of gasoline.

audunw 3y ago
Did he say “for a given highway range”? EVs are more efficient than ICE, so you gain 2-3x there. Then, if we’re talking city driving ICE is even less efficient unless they’re hybrid or ideally plug-in hybrid, in which case much of the weight benefit goes out the door. Then you’ve got the fact that batteries are now being used as a structural member, which you can’t do with a gas tank. Then there’s volumetric energy density. Gas tanks necessarily eat into the usable volume within the car. Batteries can just be integrated in the floor of the car. In theory, if you drove around with a huge gas tank you could exploit the benefits of the high energy density, getting range that an EV could never hope to match. You could drive for thousands of kilometres without refuelling. But with the gas tanks that cars are actually delivered with, for the kind of range people actually need, the weight of the engine/transmission becomes a very significant fraction of the whole drivetrain+energy storage. I really don’t see the point of throwing the “100x” number around when it’s completely obvious from looking at real-world vehicles that the actual achievable difference is far, far smaller, and that we’re 1-2 generations of battery chemistry improvements away from weight parity for a vehicle with the kind of range people actually need.
Gibbon1 3y ago
It's true that batteries will never weigh as little as a 12 gallon gas tank. But that doesn't factor in the weight of the engine and drive train. Electric motors are lighter for the same torque and power than gas engines. And they only need a simple reducing gear vs a automatic transmission.

by yodon 3y ago

audunw 3y ago

Did he say “for a given highway range”? EVs are more efficient than ICE, so you gain 2-3x there. Then, if we’re talking city driving ICE is even less efficient unless they’re hybrid or ideally plug-in hybrid, in which case much of the weight benefit goes out the door. Then you’ve got the fact that batteries are now being used as a structural member, which you can’t do with a gas tank. Then there’s volumetric energy density. Gas tanks necessarily eat into the usable volume within the car. Batteries can just be integrated in the floor of the car. In theory, if you drove around with a huge gas tank you could exploit the benefits of the high energy density, getting range that an EV could never hope to match. You could drive for thousands of kilometres without refuelling. But with the gas tanks that cars are actually delivered with, for the kind of range people actually need, the weight of the engine/transmission becomes a very significant fraction of the whole drivetrain+energy storage. I really don’t see the point of throwing the “100x” number around when it’s completely obvious from looking at real-world vehicles that the actual achievable difference is far, far smaller, and that we’re 1-2 generations of battery chemistry improvements away from weight parity for a vehicle with the kind of range people actually need.

Gibbon1 3y ago

It's true that batteries will never weigh as little as a 12 gallon gas tank. But that doesn't factor in the weight of the engine and drive train. Electric motors are lighter for the same torque and power than gas engines. And they only need a simple reducing gear vs a automatic transmission.