About this replacement
Bambook SD928+ — 3.7V Li-Polymer Replacement Battery (MLP454261)
This 3.7V, 1300mAh lithium-polymer battery replaces the MLP454261 cell in the Bambook SD928+ e-reader. It restores power to the e-ink display and onboard processor after the original cell degrades or fails to hold charge. Dimensions are 63.00 × 41.70 × 4.70 mm — confirm against your existing cell before fitting.
- SD928+ fit: The SD928+ uses a compact LiPo cell on a dedicated power rail that drives the e-ink controller and CPU. This cell matches the connector pinout and BMS voltage thresholds the SD928+ firmware expects — no modifications needed.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the bench. The BMS responded correctly at low-voltage cutoff and held stable voltage through e-ink refresh draws without dropping into protection mode.
- Post-swap charge cycle: After fitting this cell, connect via USB and run one full charge before powering on. The SD928+ firmware recalibrates its battery percentage display from a full-charge baseline — skipping this step causes the indicator to report inaccurate levels.
Why the SD928+ shows low battery immediately after a new cell is installed
LiPo cells ship in storage mode — typically between 3.6V and 3.85V — to reduce degradation during transit. The SD928+ firmware reads this as a partially depleted cell and flags a low-battery warning. The cell is not faulty. Connect the device to USB power and allow it to charge fully before first boot. Once it reaches 4.2V, the firmware will display an accurate percentage.
Page turns slowing down or freezing after a battery swap
E-ink displays require a voltage spike to refresh the panel — if the cell voltage sags below approximately 3.5V mid-draw, the controller throttles refresh speed or stalls entirely. This happens most often if the new cell was not fully charged before use. A full charge cycle resolves it. If sluggishness continues after charging, check that the battery connector is seated flat — a partial connection causes intermittent voltage drops under refresh load.