DC/DC Converters are sometimes called Reducers or Limiters, but they are a distinctly different product. Reducers/Limiters work across two 8 Volt batteries to produce approximately 12 VDC. A true DC/DC converter works across the entire pack and draws energy equally from all the batteries.
Converters have several distinct advantages.
Prolong th life of the batteries
Reduce battery warranty costs
increase the range of the vehicle
provide a regulated output that remains constant as the battery pack voltage drops
Maintains brightness of lights as the vehicle accelerates or climbs hills
There are two types of DC/DC Converter, Non-isolated and Isolated. Non-isolated has one common lead with battery pack and in the design of SPS this is the B+ lead. B+ common is the lowest cost approach and has distinct advantages when used with radios.
An isolated Converter has galvanic isolation (a transformer) between the main battery pack and the 12 V loads.
See the Isolated versus Non-Isolated page for more information.