How much does electricity weight? Like if you charge your EV, does it weigh more than when the batteries are on “empty”?

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Does “electricty” or whatever it’s called that goes into your electric vehicle battery, have mass or weigh anything? My car has a 100KW battery. Is the weight substantially different when it has 0 charge versus when it is fully charged? It seems like a lot of energy goes into the battery, it must add to the net mass of the vehicle?

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Anonymous 0 Comments

Yes It does. Charged batteries have more electrons in them then discharged and electrons weigh something. 

Plus there is the fundamental concept E=mc^2. A full battery has an amount of extra energy and thus an amount of extra mass. 

A single electron volt weights 1.8 * 10^-36 Kg. There’s 2.25 * 10^25 in a kw. 

Assuming the car battery is 100 KW/h (100KW is not a storage quantity), then you end up with 0.00405 milligrams. Which is probably the weight of a short enough human hair. 

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