A very large amount of heat will be generated dropping from 12 volts down to volts at 2.5 amps. You will be better of with a switching regulator, something like this: http://www.futurlec.com/Datasheet/Linear/LM2576T-ADJ.pdf
A very large amount of heat will be generated dropping from 12 volts down to volts at 2.5 amps. You will be better of with a switching regulator, something like this: http://www.futurlec.com/Datasheet/Linear/LM2576T-ADJ.pdf