"The track was well set-up and I really enjoyed it," said Smith afterwards. "The course had steep sections, tight stuff and plenty of areas that flowed. It had a bit of everything really.
"Jason had a crash while chasing me and that caused him to drop back a bit, but, when I came in to the pits to refuel, he swept past me. I caught him again about half a lap later and managed to retake the lead."
Smith saved his best for last; producing the day's four fastest lap times over the final four laps and creating a safe winning margin.
Charleston put in a late charge too, passing Penny, Brown and Birch on the last lap to secure the final podium position.
"He (Charleston) is riding really well at the moment. He's only a youngster and I think he'll be a real threat to me in the future," said Smith.
In the 90-minute junior race staged earlier in the day, Pukekawa's Isaac Clark won ahead of Te Kuiti's Sean Kelly and Raglan's Jaan Anderson.
Round three of the Bel Ray series is set for Waikaretu, in North Waikato, on February 9.
The Bel Ray series is a stand-alone competition, but is also an ideal warm-up for the nationals which begin next month.
The four-round New Zealand Cross-country Championships kick off in the Taranaki region on February 16, with rounds to follow in Huntly, Westland and Marlborough.