To riff on this, a lead-acid cell is 2.2v. If you look at the 12v battery in your (typical) car, it has six cells. It's less obvious with modern sealed batterie

To riff on this, a lead-acid cell is 2.2v. If you look at the 12v battery in your (typical) car, it has six cells. It's less obvious with modern sealed batteries, but super obvious with flooded lead acid batteries in golf carts. Lithium batteries do not have 2.2v cells; typical li-ion cells are 3.7v. So there's no particular reason why you should stack them to 48v, except that there's already some amount of industrial capacity for 48v components due to the preponderance of 48v golf carts. Of course, these systems don't work at exactly 12v or 48v or whatever; voltage on the bus fluctuates with state of charge (and state of charging).