Finally, a 1 kW electric radioisotope power supply running on Plutonium 238 (Pu-238) would kick in to power an ion thruster engine.

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The Tesla Roadster, which indeed uses Li-ion batteries, stores 56 kWh of electric energy and delivers up to 215 kW of electric power (a NiMH battery pack with the same electric energy would weigh over twice as much).

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The car uses a 1.8-liter, 98-horsepower four-cylinder gasoline engine with an 80 hp (60 kW) electric motor charged on a Ni-MH battery.

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