2 amps is probably sufficient and safe, unless your display uses a lot of lights, and the transmitter is very strong. The power requirements are normally listed on the back of the display housing, and indicate the size fuse required. 2 amps really isn’t much power, may have to use a 5 amp to prevent blowing the fuse under normal conditions. The unit will always draw what it wants from the battery, the fuse only sets the maximum current limit, it does not in any way force more power into the unit.