regulating 45v to 35v

hi there what is the best way I can regulate 45v DC to 35v DC 2A?
or if it is any help I could do it on the AC side? maybe us a x capacitor?

thanks Joe

How are you getting to 45 Volts to begin with ? Can you post a schematic?
Do you mean 4**.5V to 3.**5V or literally 45 to 35V?

literally 45 to 35V

the 45v is being used for something else so going to pick of that. need to drop it down for a battery charging circuit

An LM317 and a pass transistor hould do it. But it will only do 1.5 A, you might need a pass transistor to get more current.
http://www.fairchildsemi.com/ds/LM/LM317.pdf

Depending on the requirement, a zener and moderately high voltage NPN transistor should do nicely.
Look at the "example linear regulator here:

A switch-mode regulator would be most efficient, but isn't an off-the-shelf component at
those voltages and currents I suspect.

With a linear regulator you would need a pass-transistor with substantial heatsink and
maybe fan as there is 20W to dissipate.