He last raced a superbike in New Zealand in 2004, finishing fourth overall that season, before heading overseas to clinch the South Australian and Victorian superbike titles in 2006.
He returned to win the New Zealand 600cc supersport title in 2008 before making it back-to-back wins by again dominating the 600cc class last year and this year.
He feels he has the pace to win the formula one/superbike class at the Tri Series and, if his early warm-up stints on the ex-Andrew Stroud Suzuki GSX-R1000 are anything to go by, he may be right.
"I want to use the Tri Series to measure where I am at as regards a possible result in the nationals and, although I don't want to risk it all in the Tri Series with the national title my main aim, this Tri Series has enormous status on its own and I'd certainly love to win there too," said the 44-year-old Charlett.
"I'm going pretty well at the moment and I expect to improve some more when the racing proper starts. There's nothing like actual racing to sharpen you up. "Racing the 1000cc superbike has rejuvenated me.
"The superbike is quite a different beast to ride and I have to be careful on the throttle. You have to have a lot of respect for the throttle."
Charlett he says he's very grateful for the support he's been given to allow him to create the Underground Brown Race Team.
"If it wasn't for Tony Brown I wouldn't be able to do this at all. He has been a massive help to me."
In addition to facing four-time consecutive Tri Series winner and defending F1 titleholder Andrew Stroud, Charlett will have to cope with such blazingly fast individuals as Christchurch rider James Smith (Honda), Hamilton's Nick Cole (Kawasaki), Wellington's Sloan Frost (BMW), Feilding's Craig Shirriffs (Suzuki), New Plymouth's Hayden Fitzgerald (Suzuki) and Whakatane's Tony Rees (Honda).
Thomas Kreutz is also expected to challenge for the title.
Kreutz is the reigning German supersport champion and he will be racing both the F1 and F2 class on a Yamaha R6.
The Suzuki Tri Series features races for F1, F2, F3, sidecars, post-classic pre '89, BEARS, and 450cc supermoto.
The Tri Series heads to Manfeild, on the outskirts of Feilding, for round two of the Tri Series the following weekend, December 16, and it then wraps up with the traditional Cemetery Circuit event, on the public streets of Wanganui, on Boxing Day.