Batteries in which the charged liquid changes, rather than they being completely closed. So, if used in a car, you can just change the battery liquid rather than wait till it is ionized.
https://www.youtube.com/watch?v=CSawQl8Lf1Y (14:35)
The good: they can be made as big as needed, just add more tanks to store the charged material.
The bad: they are still as dense as the regular battery.
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