Choose Vcc for MOSFET driving a 48v Motor
You've got a few options to obtain a suitable voltage for driving MOSFET gates:


Take +12V from the first lead-acid battery in your series-connected bank of lead-acid batteries.  Even a drained lead-acid battery will supply sufficient voltage for gate driving.
Use a step-up converter to make higher voltage from +5V (the VDD).  With a capacitive charge pump, you can 2x the voltage.  With an inductive boost, you aren't limited to only 2x.
Use a step-down regulator (linear or buck) to create the suitable gate driving voltage from +48V.


Either of these methods can be used to create VCC in the range of voltages that you require.


source: block diagram is from p.4 of the IR2110 datasheet

see also: related thread about bootstrap gate driving