LeTV Le Pro 3 AI LTF26A Replacement Battery 3.85V 3900mAh

LeTV Le Pro 3 AI / LEX650 Series — 3.85V Li-Polymer Replacement Battery (LTF26A)

This is a 3.85V, 3900mAh Li-Polymer replacement battery for the LeTV Le Pro 3 AI smartphone, covering models LEX650, LEX651, and LEX658. It replaces part number LTF26A when the original cell has degraded, lost capacity, or stopped holding a charge. Rated at 15.02Wh, it restores power to the processor, display, and radio hardware.

• LEX650 / LEX651 / LEX658 compatibility: These three variants share the same battery bay dimensions (77.18 × 67.70 × 4.28mm), voltage rail, and connector pinout — the LTF26A fits all three without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the LEX650 platform. The BMS accepted charging current correctly and protection circuits tripped within spec on overdischarge simulation.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging is applied to an uncalibrated state.

Sudden shutdown at 20–30% on the LEX650 after a cell swap

The Le Pro 3 AI's fuel gauge IC stores a learned discharge curve from the original cell. After a cell swap, that stored curve no longer matches the new cell's actual voltage-versus-capacity profile. When the modem transmits or the display peaks in brightness, the new cell's voltage drops faster than the gauge expects, and the phone interprets this as a critical low-voltage event. Running one full discharge-to-shutdown and uninterrupted recharge cycle forces the coulomb counter to recalibrate against the replacement cell's actual behaviour.

USB fast charging not engaging on the first cycle after replacement

On the first charge cycle after fitting a new LTF26A, the charge IC may default to standard 5V / 0.5A input rather than initiating the device's fast charge protocol. This happens because the BMS presents a higher impedance on a fresh cell, and the handshake voltage threshold for fast charge negotiation is not met immediately. Let the phone charge fully at standard rate on the first cycle. Fast charge typically re-engages normally from the second cycle onward once the BMS settles and cell impedance drops.