The president of General Motors Corp. pulled up to the Mayflower Hotel in a candy-apple-red electric-powered Chevette yesterday and proclaimed a breakthrough in batteries that he said now makes electric cars commercially practical.

The new type of battery developed by GM'S Delco-Remy division can give an electric car twice the range of conventional batteries, allowing it to go 100 miles before the batteries need recharging, said E. M. "Pete" Estes, president of the world's largest automaker.

"We've cleared a major technological obstacle to our plans to begin offering electric-powered vehicles in the mid-1980s," said Estes.

"These batteries, we're convinced, eventually will make electric vehicles viable alternatives to gasoline or diesel cars and trucks."

The new GM batteries are made with zinc and nickel oxide instead of lead and sulphric acid as are conventional car batteries. The new batteries can store two or two and a half times as much electrical power as conventional batteries, giving an electric car proportionally more range between charges, Estes said.

The more powerful batteries provide an electric car with the 100-mile range that General Motors executives believe is necessary to successfully sell electric vehicles to the public, Estes said.

He wouldn't say how much the new batteries cost, but did say that GM's goal is to produce an electric car that will cost about the same to own and operate as a Chevette -- the company's smallest, least expensive and most-fuel-efficient automobile.

The electricity to run an electric vehicle costs about 1.5 cents a mile compared with 3.6 cents a mile for a car getting 27.5 miles per gallon of gasoline. But the electric car batteriesmust be replaced periodically, adding substantially to the cost.

GM hasn't made a firm commitment to produce electric cars commercially and has set no timetable for doing so, Estes stressed.

But now that the battery problem has been solved, the giant auto company will begin developing an electric car from the ground up, designing a body and chassis specifically for an electric vehicle instead of plugging batteries and an electric motor into a conventional vehicle, he added.

The electric Chevette -- renamed the Electrovette -- that Estes drove yesterday is a "test bed" meant to help develop electric vehicle components, not a prototype for GM'S first electric vehicle, he said.

General Motors' first commercially produced electric vehicle will be either a two-seat runabout for commuters or a small delivery truck for urban use, Estes added.

Estes said General Motors executives now regard electric cars primarily as second or third cars rather than as a replacement for the family auto. Even in that limited market, electric cars could account for 10 percent of total General Motors production by 1990, he said.

GM has built experimental versions of both types of vehicles, and electricpowered GMC vans are being used as service trucks by a California telephone company in a Department of Energy demonstration project.

Estes said his company has spent $33 million on electric vehicle research so far -- a relatively small amount by General Motors' standards -- and doesn't want federal funds for more research.

At yesterday's press conference -- which coincided with the introduction here of GM's 1980 models -- Estes provided few technical details of GM's "battery breakthrough."

Calling specifics about the invention "competitive information" and "trade secrets," he sidestepped a reporter who sought to pin him down on the precise nature of the "breakthrough" that Estes proclaimed. "We think it is a breakthrough; you'll have to decide for yourself," replied Estes.

The theoretical possibility of building batteries that store electricity through the chemical reaction of zinc and nickel oxide has been known for many years. But earlier zinc and nickel oxide batteries tended to short out internally and fail after only a few uses.

Delco Remy General Manager Elmer Reese said engineers found a way to eliminate the internal fouling and produce a zinc and nickel oxide battery that will last as long or longer than conventional batteries.

Reese said the latest GM batteries can be run down fully and recharged 300 times before they need to be replaced, giving an electric car's batteries a life of about 30,000 miles.

The big advantage of zinc and nickel oxide batteries is that they can be made lighter, because they can store more electricity per pound of battery. The weight of batteries is critical in electric cars because the vehicles must expend nearly half of their energy just to haul the batteries, which can weight half a ton or more in a small car.

Echoing Estes, Reese refused to estimate the cost of zinc and nickel oxide batteries. The only ones that exist so far are hand-made experimental models, he said.

Noting that zinc costs about four times as much per pound as the lead plates used in conventional batteries, Reese said he "would'nt argue too much" with reports that replacing a set of batteries in an electric car could cost between $800 and $2,000.