This Brooklyn bagel shop is saving money with plug-in batteries

In the back of Black Seed Bagels in northern Brooklyn is a giant catering kitchen filled with industrial-size condiments and freezers full of dough. A tall, silver electric oven, named the Baconator, stands in a far corner, cooking thousands of pounds of meat every week to accompany Black Seed’s hand-rolled, wood-fired bagels.

The Baconator is connected to a battery the size of a carry-on suitcase, which is plugged into the wall. While the morning rush is underway, the 2.8-kilowatt-hour...