How Replacement iPhone Batteries Are Made [Video]

iFixit has shared a new video offering a behind-the-scenes look at how replacement batteries for the iPhone are manufactured at scale.

The footage follows Lead Teardown Tech Shahram Mokhtari through a factory in China that produces nearly 13 million lithium-polymer cells a month. He walks through the assembly process, showing how battery cells are paired with the electronics needed to operate safely inside an iPhone. The tour follows iFixit's recent trip to the region where the team tore down counterfeit Apple products purchased in Shenzhen.


A major focus of the demonstration is the Battery Management System (BMS). This small board protects the battery from overcharging and deep discharging. Mokhtari shows how batches of blank BMS boards are programmed with the appropriate firmware before being spot-welded to the battery cells. The boards are then carefully folded and insulated with Kapton tape to prevent short circuits while keeping the final design as compact as possible.

While the finished product appears simple, the manufacturing process relies on precision machinery, programmed electronics, and multiple rounds of testing before a battery is ready for installation. The facility tests each battery for impedance, capacity, and overcurrent protection to ensure it is safe for use. Technicians also connect the finished units to diagnostic tools to verify that the BMS accurately reports data such as battery health, temperature, and cycle counts. After passing inspection and receiving adhesive pull strips, the replacement batteries are ready to be installed.

Take a look at the full process in the video below.