Kyocera 7035 Replacement Battery 3.7V 1200mAh Li-ion

Kyocera 7035 / 7135 / CP 7135 / 7100 — 3.7V Li-ion Replacement Battery

This 3.7V, 1200mAh Li-ion cell replaces the original battery in the Kyocera 7035, 7135, CP 7135, and 7100 smartphones. It fits the same battery bay and connects to the same charge circuit as the factory cell. Swap it in when the original no longer holds a charge or causes unexpected shutdowns.

• 7035 / 7135 / CP 7135 / 7100 compatibility: These four models share the same battery bay dimensions, 3.7V nominal voltage rail, and charge IC interface. One cell covers all four without modification or adapter.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the 7135 platform. The BMS accepted charge current from the onboard charge IC on the first cycle and reported state-of-charge to the OS without triggering any protection lockout.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle before resuming normal use. This lets the phone's fuel gauge IC map the new cell's discharge curve — skipping this step is the leading cause of erratic percentage readings after a cell swap.

Sudden shutdown at 20–30% on the Kyocera 7135

This happens because the fuel gauge IC is still running the discharge curve stored for the old, degraded cell. When the new cell's actual voltage under modem or screen load drops below the IC's predicted floor for that percentage, the phone cuts power before the cell is actually empty. One complete, uninterrupted discharge-to-charge cycle rewrites the coulomb counter baseline. After that cycle, the reported percentage tracks the real cell voltage accurately under load.

Phone won't power on after the replacement cell sat in storage

Li-ion cells self-discharge in storage. If the cell voltage drops below 2.5V, the BMS enters a protection lockout state and blocks normal charge current to prevent damage. The phone shows nothing — no boot logo, no charge indicator. Connect the phone to a wall charger and leave it for 20–30 minutes without pressing the power button. The charge IC trickle-charges the cell back above the BMS threshold, after which normal charging resumes and the phone will power on.