Nextbook Ares 8A Replacement Battery 3.7V 3900mAh

Nextbook Ares 8A / NX16A8116KPK — 3.7V Li-Polymer Replacement Battery (AE25102105P)

This is a 3.7V, 3900mAh lithium-polymer battery for the Nextbook Ares 8A and NX16A8116KPK Android tablets. It replaces OEM part AE25102105P directly. If the original cell has degraded or the tablet no longer powers on from charge, this restores normal operation.

• Ares 8A and NX16A8116KPK compatibility: Both models share the same mainboard power rail, connector pitch, and BMS handshake protocol. The AE25102105P cell seats in the same 102.60 × 98.00 × 3.00mm cavity on both boards without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Nextbook Ares 8A unit. The BMS accepted the cell without fault flags, charge IC engaged normally, and the protection circuit tripped correctly at low-voltage cutoff.
• Fuel gauge recalibration after swap: After fitting this battery, run the tablet down to automatic shutoff, then charge it uninterrupted to 100%. This forces the fuel gauge IC to recalibrate against the new cell's actual capacity curve and clears the inaccurate percentage readings common after any cell swap.

Tablet shutting down at 15–25% after battery replacement

The Ares 8A draws combined load from the display backlight and Wi-Fi simultaneously. On a new or recently swapped cell, the fuel gauge IC hasn't mapped the voltage curve of the new cell yet. At around 3.6–3.65V, the cell's actual capacity drops faster than the gauge expects, causing the protection circuit to cut power before the displayed percentage reaches zero. One complete discharge-to-shutoff cycle followed by a full uninterrupted charge resets this. After that cycle, shutdowns at 15–25% stop for most users.

Fast charging not available after fitting the replacement cell

The Ares 8A charge IC negotiates charge rate based on cell acceptance on the first few cycles. A brand-new cell sometimes causes the controller to default to a conservative charge profile until it completes one accepted charge cycle. Use the original Nextbook charger or a USB adapter that outputs 5V/2A, and let the first charge run uninterrupted from flat to 100%. After that cycle completes, the charge IC re-evaluates the rate and normal charging speed resumes.