In a ritualistic 20-minute finale yesterday to last year's long battle for the presidency, Congress formally completed the process of electing Ronald Reagan 40th president of the United States.

House and Senate, meeting jointly in the House chamber, presided over the official counting of votes cast by the Electoral College last month. There was no suspense or pageantry -- and a notable absence of lawmkers -- as the droning of tellers told what everyone already knew.

Reagan and his vice presidential running mate, George Bush, received 489 electoral votes compared to the 49 electoral votes received by President Carter and Vice President Mondale.

He only drama occurred when Mondale, presiding over the session as president of the Senate, announced his own defeat in a kind of aw-shucks manner. This prompted a lengthy standing ovation from his Capitol Hill colleagues, a tribute that the blushing Mondale acknowledged with a wave.

Although the Democrats took a drubbing in the November elections, losing the Senate as well as the White House, they applauded loudly as votes of the pro-Carter states were announced -- all five plus the District of Columbia. "It doesn't look good," said a self-mocking voice from the podium as the vote count started.

Both houses then recessed except for pro-forma sessions until Reagan's inauguration Jan. 20, with Senate committees spending the next two weeks on Cabinet confirmation hearings. Meanwhile, House Democrats named their new members to the Rules, Appropriations, Ways and Means and Budget committees.

To Rules, House Speaker Thomas P. O'Neill (D-Mass.) appointed Reps. David Bonior (Mich.) and Tony Hall (Ohio). The Democratic Steering and Policy Committee nominated Reps. Les AuCoin (Ore.), Daniel Akaka (Hawaii), Wes Watkins (Okla.), William Gray (Pa.) and Bernard Dwyer (N.J.) to the Appropriations Committee. It chose Reps. Donald Pease (Ohio), Kent Hance (Tex.) and Robert Matsui (Calif.) for Ways and Means. Designated for Budget were Brian Donnelly (Mass.), Thomas J. Downey (N.Y.), Beryl F. Anthony (Ark.), Les Aspin (Wis.) and Phil Gramm (Tex.).