Every day, Manny Ramirez crisscrosses Manhattan, ferrying takeout food, toiletries, and a host of other things that people order on apps. “They are smaller and they last less,” said Hildalyn Colón-Hernández, director of policy and strategic partnership at Los Deliveristas Unidos, an advocacy group for New York City’s delivery workers. The process is called a “thermal runaway”—the battery violently unleashing …