Simvalley XL-915 Replacement Battery 3.7V 1000mAh Li-ion

Simvalley XL-915 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1000mAh Li-ion cell for the Simvalley XL-915 smartphone. It replaces the original battery when the device no longer holds a charge or fails to power on. Capacity is 3.7Wh and dimensions are 53.00 × 33.90 × 5.70mm — measure your original cell before fitting.

• XL-915 and XL915 fitment: Both model designations refer to the same hardware platform. The battery connector, cell dimensions, and BMS voltage thresholds are identical across both variants — no adapter or modification needed.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the XL-915 platform. The BMS accepted charge from the device's onboard charge IC without error flags, and cutoff voltage held at the expected threshold under simulated load.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging if the option is available and run one full discharge-to-charge cycle. The fuel gauge IC calibrates its discharge curve against the new cell — skipping this step causes erratic percentage readings until recalibration completes.

Sudden shutdown at 20–30% on the replacement cell

This happens because the fuel gauge IC is still mapped to the old cell's discharge curve. The new cell hits a voltage cliff — a rapid voltage drop under modem or screen load — before the reported percentage reaches zero. The phone interprets this as a low-voltage emergency and shuts down. One full discharge and recharge cycle forces the coulomb counter to remap against the new cell's actual curve and eliminates premature shutdowns. After recalibration, the cutoff should track accurately down to the 3.0–3.2V threshold.

XL-915 not powering on after the battery was stored discharged

If the cell voltage dropped below approximately 2.5V during storage, the BMS enters lockout mode to prevent damage from deep discharge. The phone will show no response — no charge indicator, no boot screen. Connect the device to a wall charger and leave it untouched for 15–30 minutes. This allows the charge IC to trickle current into the cell at a safe rate until it recovers above the BMS reactivation threshold, typically around 2.9V, at which point normal charging resumes.