Apple worked with a Chinese automaker for years to design a battery system for its now-canceled car project. That’s according to Bloomberg, which reports that Apple was collaborating with BYD Co., a Shenzhen-based car company,

Before the Project Titan was scrapped, Apple reportedly worked with Chinese automaker BYD on custom batteries for Apple Car for years, but ultimately abandoned that partnership too.

As reported by Bloomberg on Wednesday, Apple has worked closely with Chinese automaker BYD. Both companies reportedly reached an agreement around 2017 to build batteries using lithium iron phosphate cells (LFP).