Apple iPhone 5s Replacement Battery 3.8V 1700mAh 616-0667

Apple iPhone 5s / 5C — 3.8V Li-Polymer Replacement Battery (616-0667)

This 3.8V, 1700mAh lithium-polymer cell replaces the original battery in the Apple iPhone 5s and iPhone 5C. It fits models including the A1526 and 30-plus additional variants that share the same battery bay and connector. Install it when the original cell no longer holds a usable charge between cycles.

• iPhone 5s and 5C platform fit: Both devices run the same 3.8V battery bay, use an identical flex connector, and share the same charge IC. One cell covers both platforms without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on an iPhone 5s board. The BMS accepted charge immediately, the charge IC held the correct 4.2V cutoff, and no thermal event occurred across three consecutive cycles.
• Fuel gauge recalibration on first use: After installing this cell, run one full discharge down to automatic shutdown and then charge uninterrupted to 100% before resuming normal use. This lets the iPhone's coulomb counter recalibrate against the new cell's actual discharge curve, so the percentage readout stays accurate from the start.

Why the iPhone 5s shuts down suddenly at 20–30% after a battery swap

A new cell has a slightly different internal resistance profile than the worn cell the fuel gauge IC was trained on. Under a heavy load spike — LTE modem transmission, display at full brightness, GPS active simultaneously — the cell voltage dips sharply. The phone's power management IC reads that dip as a low-voltage fault and forces an immediate shutdown, even though the reported percentage still looked fine. This is not a defective cell. Run one full discharge-to-shutdown cycle followed by a full charge, and the coulomb counter re-maps the voltage curve. Shutdowns at 20–30% stop once the IC has one clean calibration cycle logged.

Device will not power on after sitting discharged in storage

Lithium-polymer cells that drop below roughly 2.5V trigger a BMS lockout — the protection circuit disconnects the cell to prevent damage. Plugging in a charger at this point may show no response at all on screen. Connect the phone to a wall adapter rather than a computer USB port, which cannot always supply enough current to wake a locked-out BMS. Leave it connected for at least 15 minutes with no response expected on screen — the charge IC trickle-charges the cell back above 2.8V, at which point the BMS re-engages and normal charging resumes. If the Apple logo still does not appear after 30 minutes on a wall adapter, confirm the charging cable is not the fault before replacing the cell again.