Amazon.com: DC DC Converter 48V to 12V, Power Source Voltage Step Down Converter 10A 120W DC to DC Converter 48V to 12V Voltage Buck Converter : Electronics
48V to 12V 25A 300 Watt DC/DC converter PKL4313PITLA from Ericsson, in stock
12V to 48V 10A 480W DC DC Step Up Converter Voltage Regulator – Daygreen