7. How are voltage sensitive loads protected when connected to the charger output?
The simplest method involves switching a chain of power diodes in and out of circuit depending upon the battery voltage at any given period. Heavy duty contacts are used to short out the diode chain which is connected in series with the supply to the load.
DC-DC Converters provide an electronic equivalent to the above. They have the ability to deliver a tightly regulated DC supply from an input derived from the battery with an operating potential which can rise or fall below the converters output voltage. You can actually charge one battery with another with the same potential using one of these units provided there is enough surplus power in the source battery to begin with. This type of unit is called a Switch Mode DC-DC converter.