Our garage has no mains connection, but it does have a 12V leisure battery charged from a solar panel, connected to an inverter to produce 240V AC. That mainly gets used for charging a mobility scooter that's kept in the garage overnight, and the mobility scooter runs off a 24V battery.
The current setup – converting the nominal 12V DC to 240V AC then back to (approximately) 24V DC to charge the scooter battery – seems grossly inefficient to me. It seems like it should be possible to set up a charging system that converts from 12V DC straight to 24V DC. But I'm utterly failing to find a sensible way to achieve that. What would I need to charge the 24V battery from the 12V one without converting to AC as an intermediate step? Or is it just A Bad Idea for some reason I haven't spotted?
Ideally I'd like the 24V system to be some sort of intelligent charging system, i.e. adjusting the charging voltage and current according to the battery voltage. I'd also vastly prefer to not need to rewire the scooter batteries from the 24V series layout to a 12V parallel layout.