Krome BTR5600B Smartphone Compatible Battery 3.7V 2200mAh

Krome BTR5600B / ST26A / ST26B — 3.7V Li-ion 2200mAh Replacement Battery

This is a 3.7V lithium-ion cell rated at 2200mAh (8.14Wh), sourced to match the OEM part numbers BTR5600B, ST26A, and ST26B. It replaces the original battery in compatible smartphones when the existing cell can no longer hold a full charge. Voltage and connector spec match the original to work with the device's existing charge IC and fuel gauge circuit.

• BTR5600B / ST26A / ST26B platform fit: These three part numbers share the same cell format, voltage rail, and connector pinout — which is why one replacement covers all three. The BMS handshake on each variant communicates over the same lines, so the charge IC accepts this cell without requiring a firmware workaround.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a bench rig matching the OEM voltage profile. The BMS held cutoff correctly at the low-voltage threshold and accepted a full charge cycle without triggering protection mode.
• First-cycle fuel gauge recalibration: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This allows the fuel gauge IC to map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated reference.

Sudden shutdown at 20–30% after fitting the replacement cell

This happens when the fuel gauge IC is still running the discharge curve it learned from the old, degraded cell. The replacement cell has a steeper voltage drop under modem or screen load than the gauge expects at that state-of-charge. When voltage sags below the processor's minimum rail during a high-draw moment — even briefly — the phone shuts down as a protective measure. Running one full discharge to 0% and a complete charge to 100% lets the coulomb counter relearn the new cell's curve and eliminate premature cutoffs.

Phone not powering on after the battery sat discharged in storage

Li-ion cells shipped or stored in a deeply discharged state can drop below 2.5V per cell, which triggers a BMS lockout to prevent unsafe charging. The phone will show no response to the power button and may not register on a charger at all. Connect to a wall charger — not a USB port — and leave it for 20–30 minutes without attempting to power on. Once the BMS detects the cell has recovered above its reinitialisation threshold, typically around 3.0V, normal charging resumes.