According to his LinkedIn profile, which does not yet reflect his change in employment, Villanueva most recently held the title of senior manager of Battery Module Design. The engineer had worked for Tesla since 2006, when the company was just three years old and Elon Musk held the role of chairman, but not yet CEO. Villanueva left the company some months ago, according to a person familiar.

A battery tech leader at Tesla , Ernest Villanueva, left the company last year, CNBC has learned. Villanueva holds numerous patents and helped design the battery modules that power all of Tesla's vehicles, including the Roadster, Model S, Model X and Model 3.

Tesla declined comment. Villanueva did not immediately respond to requests for comment.

Tesla has had to reduce its Model 3 production targets, in part because of issues with battery manufacturing. Some employees involved in battery production told CNBC that the company was assembling batteries by hand as recently as December, and said they were skeptical that it can accomplish its revised goals and manufacture 5,000 Model 3s per week by June. Tesla maintains that it is on track to meet those goals.

Villanueva is one of several influential engineers to leave Tesla in recent months.

Earlier this month, Uber poached Celina Mikolajcza, a former senior manager for battery pack development at Tesla. She is now working on flying cars for Uber.

Additionally, Jalopnik reported on the departures of Jason Mendez and Will McColl this month. They were, respectively, a senior director for manufacturing engineering and a senior manager for equipment engineering, both involved with the production of the Model 3, Tesla's electric sedan.