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Comment by VladVladikoff | Hacker News Reader

>Achieves 178.7 Wh/kg energy density and 8.3 kW/kg power density

Can someone explain this to me please. What is “energy” measuring here? How is it different from power?

W = Watt. h = hour. One kg supply one watt of power for 178.7 hours (without considering other factors). Power is how much energy can it supply at a moment. Up to 8.3 kW instantaneous.

Does it follow that 8.3 kW instance lasts .1787th of an hour?

No, it would last .0215th of an hour or ~77.5 seconds.

Is it a base 60 thing, how did you do the math?

There's no base 60 involved, it's the energy available divided by the power delivered:

178.8 Watt hours / 8300 Watts ≈ 0.0215 hours

Thanks, Not sure where my math went wrong.

Hours to seconds conversion probably, the number 60 plays a role there. (Albeit not base 60 but mod 60, but I'm not firm enough in the math to rule out that there is some correspondence between the concepts)

Energy is how much work you can do. Power is how fast you can do it. When you express these in terms of densities, it’s how much energy a certain quantity of material can store, and how quickly that energy can be released from a certain quantity of material.

If you short out a AA battery, it will get warm for a little while. If you short out a 14500 Li-ion battery (which is the same size and comparable energy density), you might get a small explosion as it dumps its energy very quickly.

Power is the time derivative of energy.

yeah I'm sure that someone who doesn't understand the difference between power and energy definitely understands derivatives...

you somehow managed to be perfectly unhelpful, condescending and insecure at the same time?

presumably energy is how much it can store and power is how fast you can get it out?

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