About this replacement
Kingston MLW221 — 3.7V Li-ion Replacement Battery (WMTM-169)
This is a 3.7V, 1500mAh Li-ion replacement battery for the Kingston MLW221 digital storage device. It fits the MLW221 directly, using OEM part number WMTM-169 as the compatibility reference. Install it when the original cell has degraded and the device no longer holds a usable charge.
- MLW221 platform fit: The MLW221 uses a compact single-cell Li-ion configuration at 3.7V nominal. This cell matches that voltage rail and the physical footprint — 50.20 × 51.30 × 5.50mm — so the connector seats correctly and the storage management system sees a valid cell on startup.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the MLW221 platform and confirmed the BMS accepted the cell without a fault code. Capacity read-back stabilised after a full calibration cycle rather than the first charge.
- MLW221 calibration cycle after install: The MLW221 storage management system estimates remaining capacity based on learned cell behaviour. After fitting a new cell, run the device down to low charge and then charge it fully in one uninterrupted session — this lets the firmware anchor its capacity estimate to the new cell's actual range.
Storage battery not accepted by the MLW221 after installation
The MLW221 storage management system validates the new cell during the first few charge cycles, not immediately on insertion. If the device shows a battery fault or refuses to complete a charge shortly after install, this is the firmware re-initialising against an unfamiliar cell profile. Give the system up to 24 hours of normal use and at least one full charge cycle. If the fault clears, the cell has been accepted — no hardware fault exists.
MLW221 showing lower capacity than 1500mAh after replacement
A new cell installed into the MLW221 does not automatically update the firmware's stored capacity estimate — the old cell's degraded profile may still be active. The device reports what it learned from the previous cell until a calibration cycle overwrites it. Discharge the device until it shuts off on its own, then charge uninterrupted to 4.2V full. After that single cycle, the capacity estimate displayed should align with the 1500mAh rating.