Coupled with his opening round 64, Percey stands at 8-under for the tournament and was joined at the top by Queenslander Andrew Bonhomme, who fired his second straight 67.
Being played at the Portsea and Sorrento Golf Club on the Mornington Peninsula, Bonhomme's 4-under was the low score of the day, as blustery conditions had players scrambling to make par.
Percey and Bonhomme hold a three-stroke lead over a trio of players- New Zealander Mark Brown(68-69), Victorian amateur Marc Leishman(69-68) and the ACT's Craig Carmichael(67-70).
Ewan Porter, Alastair Sidford and Daniel Stevenson are four off the pace, tied for sixth at 4-under.
A large group six players are a stroke further back at 3-under.