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>5 to 7 minutes for recharging The article is light on specifics but this stood out to me, most Tesla's take longer to charge. I'd imagine an aircraft would ne

>5 to 7 minutes for recharging The article is light on specifics but this stood out to me, most Tesla's take longer to charge. I'd imagine an aircraft would need more power than a Tesla, so how are they transferring energy so fast that automobiles can't do it but aircraft can?

noodlesUK 7y ago
It may not be a particularly large battery, as it’s got to take off vertically. It’s not a very long range either, just short hops.
- pishpash 7y ago
  Seems like not having enough range is a much bigger problem than for a car.
clouddrover 7y ago
Different battery chemistries have different C-rates, which is the rate at which a battery can be charged and discharged: https://web.mit.edu/evt/summary_battery_specifications.pdf https://web.mit.edu/evt/summary_battery_specifications.pdf https://batteryuniversity.com/index.php/learn/article/what_is_the_c_rate https://batteryuniversity.com/index.php/learn/article/what_i... And generally bigger battery packs can charge at higher kilowatts. Here's an electric ferry with a 4.1 MWh battery which can charge at up 6 megawatts. 600 amps at 10,000 volts: https://www.youtube.com/watch?v=rE_M1n-ClOA https://www.youtube.com/watch?v=rE_M1n-ClOA So, like the ferry, these aircraft probably have big batteries that they charge enough to get to the next destination with a buffer for emergencies. The closer you get to 100% state of charge the slower the system will charge in order to protect the battery.
michaelt 7y ago
Under absolutely ideal conditions, a Tesla on a 250kW charger for 8.5 minutes can regain 40% of battery capacity [1] So, if you carry 2.5x the battery you need, so a 40% charge is all you ever need, then maybe? Although obviously, that would add to your weight, reducing your range. If you were willing to hook up a supply of cooling water while charging, you might be able to do somewhat better - one of the key limiting factors in fast charging is the batteries heating up. [1] https://insideevs.com/news/356710/tesla-model-3-test-v3-supercharger/ https://insideevs.com/news/356710/tesla-model-3-test-v3-supe...
walrus01 7y ago
> The article is light on specifics but this stood out to me, most Tesla's take longer to charge. I'd imagine an aircraft would need more power than a Tesla, so how are they transferring energy so fast that automobiles can't do it but aircraft can? If I had to guess the 5 to 7 minute figure is based on some theoretical magical battery that nobody can buy yet. Something with Wh/density much greater than the current best lithium ion (1000 to 1200Wh/kg vs 245Wh/kg) and capable of much higher C rates for charge and discharge. It's a mock up so they don't have to, or want to share any more detail than a optimistic time figure.

noodlesUK 7y ago

It may not be a particularly large battery, as it’s got to take off vertically. It’s not a very long range either, just short hops.

pishpash 7y ago
Seems like not having enough range is a much bigger problem than for a car.

clouddrover 7y ago

Different battery chemistries have different C-rates, which is the rate at which a battery can be charged and discharged: https://web.mit.edu/evt/summary_battery_specifications.pdf https://web.mit.edu/evt/summary_battery_specifications.pdf https://batteryuniversity.com/index.php/learn/article/what_is_the_c_rate https://batteryuniversity.com/index.php/learn/article/what_i... And generally bigger battery packs can charge at higher kilowatts. Here's an electric ferry with a 4.1 MWh battery which can charge at up 6 megawatts. 600 amps at 10,000 volts: https://www.youtube.com/watch?v=rE_M1n-ClOA https://www.youtube.com/watch?v=rE_M1n-ClOA So, like the ferry, these aircraft probably have big batteries that they charge enough to get to the next destination with a buffer for emergencies. The closer you get to 100% state of charge the slower the system will charge in order to protect the battery.

michaelt 7y ago

Under absolutely ideal conditions, a Tesla on a 250kW charger for 8.5 minutes can regain 40% of battery capacity [1] So, if you carry 2.5x the battery you need, so a 40% charge is all you ever need, then maybe? Although obviously, that would add to your weight, reducing your range. If you were willing to hook up a supply of cooling water while charging, you might be able to do somewhat better - one of the key limiting factors in fast charging is the batteries heating up. [1] https://insideevs.com/news/356710/tesla-model-3-test-v3-supercharger/ https://insideevs.com/news/356710/tesla-model-3-test-v3-supe...

walrus01 7y ago

> The article is light on specifics but this stood out to me, most Tesla's take longer to charge. I'd imagine an aircraft would need more power than a Tesla, so how are they transferring energy so fast that automobiles can't do it but aircraft can? If I had to guess the 5 to 7 minute figure is based on some theoretical magical battery that nobody can buy yet. Something with Wh/density much greater than the current best lithium ion (1000 to 1200Wh/kg vs 245Wh/kg) and capable of much higher C rates for charge and discharge. It's a mock up so they don't have to, or want to share any more detail than a optimistic time figure.