The transition from 5v to 3v PS 2 took place over a number of years. If you have the ABA MTH set number (20-****-1) you can access the MTH site and look up the manual. The manual will sometimes give a definite answer, sometimes not.
the 2001 set was PS2 with a 5v system. Your later version may have a good chance of being 3v. Do you have pictures? The 5v will have a round charging port while a 3v will have the square charging port...both located on the underside to the master unit..
This is a three volt port...
Tom