3 ms·

in theory 15 minutes flight with no reserve and you can't test it on altitude on real life ;)

by elmar 10y ago

seanp2k2 10y ago
Ah, so just like off-the-shelf RC planes at the moment, then :) Batteries are heavy. Gasoline has tons of energy for how much it weighs. New battery tech shows up on HN all the time and I've never seen one come to market. LIFePO4 and other similar lithium chemistries are still state-of-the-art in terms of what you can buy right now. https://en.m.wikipedia.org/wiki/Energy_density https://en.m.wikipedia.org/wiki/Energy_density has a comparison. Lithium air batteries are in the extended reference table here https://en.m.wikipedia.org/wiki/Energy_density_Extended_Reference_Table https://en.m.wikipedia.org/wiki/Energy_density_Extended_Refe... From https://en.m.wikipedia.org/wiki/Lithium–air_battery https://en.m.wikipedia.org/wiki/Lithium–air_battery : "Indeed, the theoretical specific energy of a non-aqueous Li-air battery (in the charged state with Li2O2 product and excluding the oxygen mass) is ~12 kWh/kg. This is comparable with the theoretical specific energy of gasoline (~13 kWh/kg). In practice, the Li-air batteries with a specific energy of ~1.7 kWh/kg at the cell level have been developed." "However, the areal power and cycle life of lithium–oxygen–air batteries need significant improvements before they can find any competitive market niche." So, they're still an order of magnitude away from gasoline and you can't buy one today (or probably in 20 years either).
- FabHK 10y ago
  To be fair, electric engines are much more efficient than internal combustion engines, so you don't need to achieve the same specific energy to achieve comparable outcomes. But, to be realistic, one of the startup "stars" of the battery scene, Envia, is marketing an aviation battery with 0.35 kWh/kg, so I'd say that's realistic state of the art. So, even getting the 1.7 kWh/kg you mentioned in a production-ready battery would be huge. http://www.enviasystems.com/products/#aerial http://www.enviasystems.com/products/#aerial

in theory 15 minutes flight with no reserve and you can't test it on altitude on real life ;)

by elmar 10y ago

in theory 15 minutes flight with no reserve and you can't test it on altitude on real life ;)

Ah, so just like off-the-shelf RC planes at the moment, then :) Batteries are heavy. Gasoline has tons of energy for how much it weighs. New battery tech shows up on HN all the time and I've never seen one come to market. LIFePO4 and other similar lithium chemistries are still state-of-the-art in terms of what you can buy right now. https://en.m.wikipedia.org/wiki/Energy_density https://en.m.wikipedia.org/wiki/Energy_density has a comparison. Lithium air batteries are in the extended reference table here https://en.m.wikipedia.org/wiki/Energy_density_Extended_Reference_Table https://en.m.wikipedia.org/wiki/Energy_density_Extended_Refe... From https://en.m.wikipedia.org/wiki/Lithium–air_battery https://en.m.wikipedia.org/wiki/Lithium–air_battery : "Indeed, the theoretical specific energy of a non-aqueous Li-air battery (in the charged state with Li2O2 product and excluding the oxygen mass) is ~12 kWh/kg. This is comparable with the theoretical specific energy of gasoline (~13 kWh/kg). In practice, the Li-air batteries with a specific energy of ~1.7 kWh/kg at the cell level have been developed." "However, the areal power and cycle life of lithium–oxygen–air batteries need significant improvements before they can find any competitive market niche." So, they're still an order of magnitude away from gasoline and you can't buy one today (or probably in 20 years either).

FabHK 10y ago
To be fair, electric engines are much more efficient than internal combustion engines, so you don't need to achieve the same specific energy to achieve comparable outcomes. But, to be realistic, one of the startup "stars" of the battery scene, Envia, is marketing an aviation battery with 0.35 kWh/kg, so I'd say that's realistic state of the art. So, even getting the 1.7 kWh/kg you mentioned in a production-ready battery would be huge. http://www.enviasystems.com/products/#aerial http://www.enviasystems.com/products/#aerial