Converting -48 VDC to +12 or +24 VDC 10 Amps or more
You don't have to convert polarity.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. A possible solution.

If you use a step-down DC-DC power supply you can run the LEDs as shown in Figure 1. 


You need to make sure your power supply hasn't got an internal ground connection on the negative output.
You need to make sure that your LED lightgs aren't grounded on their negative terminals.