Small electric vehicles have a greater climate impact than cars

In Darbhanga, a new acid-battery rickshaw like Mr. Rai’s sells for about 175,000 rupees, or $2,100. That is half the price of a new natural gas rickshaw. Charging the battery costs 20 rupees (25 cents), a quarter of the price of filling a gas tank.

The discounts seem to be working. Reliance Industries, India’s largest company, is converting its three-wheeled freight vehicles from gas to electric. Food delivery services are going electric as soon as possible.

Chetan Maini, whose company Sun Mobility builds charging infrastructure, said sales were growing rapidly. Battery prices are falling, bringing down the costs of electric two- and three-wheelers. “If the crossover point happens here,” Mr. Maini predicted, “the effect will be very fast, in the shape of a hockey stick, because it is more price sensitive.”

According to dealer Balaji Motors, around 200 electric rickshaws are sold every month in Darbhanga. A sales manager estimates that within two years, electric rickshaws will dominate the streets.

By Indian standards, Darbhanga, with a population of 300,000, could be called a sleepy town. However, it is not quiet. Loudspeakers blast music from temples and advertising jingles from open-air shops. Horns toot; engines sputtering.

In that soundscape, Mr. Rai’s purring electric rickshaw is a relative rarity, one that delighted a recent passenger, a retired teacher named Satyen Vir Jha.