BH6X Motorola MB860 Replacement Battery 3.7V 1550mAh

Motorola Atrix 4G / MB860 — 3.7V Li-ion Replacement Battery (BH6X)

This 3.7V, 1550mAh Li-ion cell replaces the original BH6X battery in the Motorola MB860, Atrix 4G, Olympus, and XT865. It fits directly into the same battery bay with the same connector and contact layout. Capacity matches the factory specification at 1550mAh (5.74Wh).

• MB860 / Atrix 4G platform fit: These models share the same 3.7V single-cell architecture, BH6X form factor, and contact pin arrangement. The BMS handshake on each uses the same NTC thermistor line, so the charge IC recognises this cell without flagging an authentication error.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the MB860. The BMS accepted charging from the stock charger without triggering thermal cutoff, and the fuel gauge IC read voltage correctly across the full range after one complete cycle.
• Fuel gauge recalibration on first use: On first installation, run one full discharge to low battery warning, then charge uninterrupted to 100% before normal use. The Atrix 4G's coulomb counter calibrates its zero and full reference points during this first cycle — skipping it causes the gauge to report inaccurate percentages from the start.

Sudden shutdown at 20–30% on the Atrix 4G after a cell swap

This happens because the fuel gauge IC is still calibrated to the discharge curve of the old, degraded cell. The new cell has a steeper voltage-versus-capacity curve, so the IC underestimates remaining charge and the phone hits the low-voltage cutoff earlier than the percentage shown. Under modem or display load, the cell voltage drops fast enough to trigger the hardware protection circuit before the OS can warn you. One full discharge-charge cycle lets the coulomb counter map the new cell's actual curve and correct the shutdown point.

Phone not powering on after the replacement cell sat in storage

Li-ion cells self-discharge during storage, and if the cell dropped below roughly 2.5V, the BMS enters lockout mode to prevent damage to the cell chemistry. The phone will show nothing — no charging indicator, no boot — because the BMS blocks current flow entirely at that voltage. Connect the original Motorola charger and leave it for 20–30 minutes without pressing any buttons; the charge IC applies a low-current pre-charge to bring the cell above the BMS recovery threshold, typically around 2.8V. Once the charging LED appears, the BMS has released lockout and normal charging resumes.