What do DC to DC chargers do for an off road vehicle?
A DC to DC charger is an electronic circuit that raises the DC voltage level, facilitating a more efficient converter with 100% efficiency... reducing the input level to a lower value at the output in the same proportion that it raises the value of the input voltage.
The low down on DC to DC chargers.
DC to DC chargers are normally found in off road vehicles, RVs, heavy trucks, buses, marine, land mobile radios, CB radios, lighting systems and AM/FM receivers.

What is the difference between non-isolated & isolated DC to DC chargers?
Isolated DC-DC chargers, also called ‘galvanic isolated', deliver full dielectric isolation (no electric contact) between input and output circuits with a high frequency transformer... this is often required by safety legislation.
Isolated units emit a loud noise and interference blocking capability, delivering the load a cleaner DC source which is required by many sensitive loads. Normal uses include communications, entertainment & navigation systems and forklifts.

What are the advantages of isolated DC to DC chargers?
Isolation prevents input voltage from transmitting to the output in case of internal failure. Voltage transients on the input are not transmitted to the output.

Why would you choose non-isolated DC to DC chargers?
Non-isolated DC to DC chargers are more common and cost less. They are often employed in negative ground applications in vehicles which have DC powered appliances and equipment. They do have one big disadvantage in that the electrical connection between the input and output offers little or no protection to the load for from high electrical voltage. They also have less noise filtering blockage.
Some common equipment which needs uses non-isolated DC to DC chargers are items not requiring noise suppression, or items which could also be used as a maintenance charger given the higher output voltage.