Robert Triggs / Android Authority
TL;DR
- A new behind-the-scenes video by iFixit explores a factory floor in China that produces nearly 13 million smartphone battery cells every month.
- The video reveals that raw cells require dedicated circuit boards flashed with custom software to prevent dangerous overcharging.
- Before shipping, each battery is tested by diagnostic equipment to verify its capacity, safety thresholds, and 100% health.
Ever wondered what actually goes into making the batteries for your smartphone? A new behind-the-scenes video by iFixit pulls back the curtain on how its iPhone replacement batteries are really made, taking us straight to the factory floor in Weao, China, where nearly 13 million smartphone battery cells are produced every single month.
While a smartphone battery might look like a simple pack of solid chemicals from the outside, turning a raw lithium-polymer cell into a fully functional, device-ready component requires meticulous precision engineering, software programming, and strict quality control.
The process of making a battery begins with the lithium-polymer cell itself, which consists of dozens of folded, ultra-thin layers assembled to microscopic tolerances.
However, you can’t just apply raw electricity to these cells — you can, but it would be extremely dangerous, highly risky, and not advisable for daily use at scale. A good battery setup requires a dedicated Battery Management System (BMS) board to safely regulate power.
In the factory, rows of blank BMS boards are attached to a specialized programming machine that flashes the necessary safety software to prevent dangerous overcharging and overdischarging. Once programmed, the BMS board and its connector cable are welded directly to the raw cell.
To ensure a compact footprint that fits inside a modern iPhone, the BMS is carefully folded over the cell. To prevent catastrophic short circuits during this folding process, technicians apply specialized tape to the edges before securing the final, folded assembly with an external sticker.
Before any finished battery can leave the factory floor, it must undergo a rigorous gauntlet of quality control checks. Dedicated diagnostic machines test each battery for its internal impedance, overall capacity, and overcurrent safety thresholds. Furthermore, the BMS is read electronically to verify key metrics, such as confirming that the initial state of health is set to 100% (or slightly higher) and that the design capacity meets Apple’s strict requirements.
The final touch before packaging involves applying the notorious pull-tab adhesive strips, turning a raw cell into the familiar battery ready to power your next device. The video provides a fascinating look into a piece of tech we often take for granted, so give it a watch!
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