Polyamp DC/DC converters use both very wide input as well as optimized for a specific input voltage (usually nominal battery voltage). In general a more optimized input voltage range result in higher power efficiency. Wide input ranges can be used in case the application has different input voltages to have less inventory. Another reason is that the application produces Cranking or Surges that must be handled e.g. vehicle applications, military, railway, especially Diesel locos.