Huawei Honor V8 HB376787ECW Replacement Battery 3.8V 3400mAh

Huawei Honor V8 — 3.8V Li-Polymer Replacement Battery (HB376787ECW)

The HB376787ECW is a 3.8V, 3400mAh lithium-polymer cell that fits the Honor V8 and Honor V8 Premium (KNT-AL20, KNT-AL10). It replaces the original battery when the existing cell has degraded through charge cycles and can no longer hold a stable voltage under load. Capacity is 12.92Wh, matching the factory specification.

• Honor V8 and V8 Premium fit: Both variants — KNT-AL20 and KNT-AL10 — use the same 3.8V cell with identical connector pitch and BMS handshake. One cell covers both boards without modification.
• Bench tested on actual hardware: We ran the HB376787ECW through a full charge cycle and monitored BMS communication. The protection circuit tripped correctly at the low-voltage cutoff and accepted charge current without error flags on the charge IC.
• 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 map the new cell's discharge curve before high-current charging begins. Skipping this step causes the percentage display to drift during early cycles.

Sudden shutdown at 20–30% on the Honor V8 after a cell swap

A fresh lithium-polymer cell has a steeper voltage cliff than a broken-in cell. When the modem transmits or the display peaks brightness, the instantaneous current draw pulls the terminal voltage below the BMS cutoff — even if the coulomb counter still shows 25%. The phone shuts down to protect the cell, not because charge is actually gone. One full discharge-to-empty and uninterrupted charge cycle lets the fuel gauge IC recalibrate its internal model against the real discharge curve of the new cell, and shutdowns at mid-percentage typically stop after that first cycle.

USB fast charge not accepted on the first cycle after replacement

Huawei's proprietary fast charge protocol requires the charge IC and BMS to negotiate current limits before stepping up from 5V standard charge. On a freshly installed cell, the BMS may reject the elevated current on the first handshake and fall back to 5W standard charging. This is a safety default, not a fault with the cell. Charge the phone once at standard rate until full, then reconnect with the original Huawei fast charger — the BMS handshake completes correctly on the second cycle once the cell voltage is within the expected window.