Today, on the day that it unveils its new battery plant in Schenectady, N.Y., GE Transportation has announced plans for a $70 million expansion that will add 100 new jobs.

The new Durathon batteries, which are half the size of traditional lead acid batteries but last 10 times longer, are already finding buyers. GE Transportation, based in Lawrence Park, has announced that Megatron Federal in South Africa has agreed to buy 6,000 of the batteries to support the telecom industry in Nigeria.

The company’s state-of-the-art batteries were originally intended for a different purpose. Company engineers had been seeking a way to store power for GE Transportation’s prototype hybrid locomotive.

The hybrid locomotive isn’t in production yet, but can be ready when the market is, said Stephan Koller, a spokesman for the company.

Meanwhile, he said, the batteries are being used for a wide range of other uses.

Jeff Immelt, General Electric Co.’s chief executive, was to tour the plant this morning with Lorenzo Simonelli, chief executive of GE Transportation.

With the expansion announced today, the plant is expected to employ about 450 people.