allenout t1_j7s78j6 wrote on February 9, 2023 at 12:55 AM

Reply to comment by Midori_Schaaf in A new lithium-air battery design promises unprecedented energy density | A potentially transformative technology for electrifying transportation by chrisdh79

Bear in mind, electric motors can be 95+% efficient while ICE cars are at best 25% efficient, so that means that ICEs are actually more like 2kWh/kg while metal air batteries are 1kWh/kg+, so a electric car would only need about 2x the size of full fuel tank as a ICE car.

SandAndAlum t1_j7t3xcw wrote on February 9, 2023 at 5:13 AM

You also need to include regen. And the fact the tank has a weight.

1kWh/kg is roughly on par with a small reciprocating ICE.

allenout t1_j7t4ims wrote on February 9, 2023 at 5:18 AM

The fuel tank is made from thin plastic so the weight is largely irrelevant.

SandAndAlum t1_j7t5ie3 wrote on February 9, 2023 at 5:28 AM

They're still >20kg when plastic, and the last few I saw were steel and weighed as much as the fuel.

ctudor t1_j7wed8j wrote on February 9, 2023 at 9:46 PM

i think ICE engine and specific parts add more weight than their electric counterparts.

solotryps t1_j7y84cg wrote on February 10, 2023 at 6:28 AM

An ICE transmission also wastes a lot more power than a simple EV reduction gear

mrSunshine-_ t1_j7t4kxk wrote on February 9, 2023 at 5:19 AM

Petrol density is something like 0,72, so it drops even more. In 50 kg petrol space you get 75kg battery.