SNN5843 Verizon Droid Replacement Battery 3.7V 1300mAh

Verizon Droid / Milestone A855 — 3.7V Li-ion Replacement Battery (SNN5843)

This 3.7V, 1300mAh Li-ion cell replaces the original battery in the Verizon Droid, Milestone, A855, and Droid Pro. It matches the OEM form factor and connector pinout so it seats without modification. Capacity figures come from the product data, not third-party claims.

• Droid / Milestone platform fit: The A855, Milestone, and Droid Pro share the same 3.7V single-cell architecture and SNN5843 footprint. The connector and BMS handshake protocol are consistent across these variants, so one cell covers the full group without adapter hardware.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Droid platform and confirmed the BMS accepted the charge profile without triggering an overcurrent cutoff. Voltage held steady at 3.7V nominal under screen-on and modem-active load.
• Fuel gauge recalibration on first cycle: After installing this cell, disable fast charging and run one full discharge down to auto-shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC a clean reference curve against the new cell before high-current charging cycles begin.

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

The Droid's fuel gauge IC was calibrated to the discharge curve of the old, degraded cell. When you install a fresh cell, the IC's voltage-to-percentage map no longer matches actual cell voltage under load. The modem radio and display draw a surge of current, the cell voltage dips sharply, and the IC interprets that dip as empty — triggering shutdown even though capacity remains. One full uninterrupted discharge-charge cycle resets the coulomb counter and removes the mismatch.

Phone will not power on after the replacement battery sat in storage

Li-ion cells self-discharge in storage, and if this cell dropped below 2.5V per cell before installation, the BMS enters a lockout state to prevent unsafe charging. The Droid will show no response — no charge indicator, no boot screen. Connect to a wall charger, not a USB port, and leave it undisturbed for 20–30 minutes. The charge IC trickle-charges at low current to bring the cell above the BMS recovery threshold, typically around 2.8V, before normal charging resumes.