Most Chinese RAMPS boards have 16V capacitors on board, so they are only good for about 15V maximum. The Arduino Mega has a 20V limit, but if you are running anything else from the 5V rail (e.g. LCD display) then the regulator is likely to overheat before that. DRB8825 chips are rated at 45V.
More modern controller boards are generally good for at least 24V, some higher (e.g. Duet is rated at 35V absolute maximum).
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
