Dopod PM16A 828 Replacement Battery 3.7V 2500mAh

Dopod 828 — 3.7V Li-Polymer Replacement Battery (PM16A)

This is a 3.7V, 2500mAh Li-Polymer replacement battery for the Dopod 828 smartphone. It replaces OEM part numbers PM16A, 35H-00051-03M, and 35H00051-00. If the original cell no longer holds a charge or the phone shuts down unexpectedly, this is the direct cell swap.

• Dopod 828 fitment: The 828 uses a fixed connector and a BMS handshake tied to the 3.7V Li-Polymer cell format. This replacement matches that voltage rail and connector pinout, so the phone's charge IC communicates with the new cell without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge using a load tester matched to the 828's draw profile. The BMS engaged cutoff correctly at the low-voltage threshold and accepted a full charge without triggering over-voltage protection.
• Fuel gauge recalibration on first cycle: After installing this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100%. The 828's fuel gauge IC was calibrated to the old cell's discharge curve — one full cycle resets it to the new cell's actual capacity curve.

Why the Dopod 828 reports wrong battery percentage after a cell swap

The 828 uses a coulomb-counting fuel gauge IC that builds its percentage model from the previous cell's charge and discharge history. Swap in a new cell and that model is immediately out of sync — the IC is still referencing an old discharge curve with different internal resistance and capacity characteristics. This causes the percentage to read high early in discharge and then drop suddenly in the lower range. One full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the IC to rewrite its reference curve against the new cell.

Sudden shutdown at 20–30% on the Dopod 828

This is a voltage cliff symptom, not a capacity problem. When the modem transmits or the screen backlight peaks, current draw spikes sharply — and an aged or uncalibrated cell cannot hold its voltage above the 3.2V cutoff threshold under that load. The BMS reads an undervoltage condition and shuts the phone down even though the fuel gauge still shows charge remaining. After the recalibration cycle described above, the fuel gauge IC maps the actual usable voltage window of the new cell and shutdown at 20–30% stops occurring.