Digma E628 Compatible Battery 3.7V 1450mAh 306070PL

Digma E628 / R657 — 3.7V Li-Polymer Replacement Battery (306070PL)

This is a 3.7V, 1450mAh Li-Polymer cell using OEM part number 306070PL. It fits the Digma E628 and R657 e-readers. The physical dimensions are 72.40 × 59.90 × 4.00mm — measure your original cell before ordering if you are unsure.

• E628 and R657 compatibility: Both models draw from the same 3.7V single-cell architecture and share the same connector pinout and BMS handshake protocol. One cell serves both platforms without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the E628 mainboard. The onboard BMS accepted the cell without fault flags, and voltage regulation to the e-ink display controller stayed within spec across the full discharge curve.
• Post-swap charge cycle on the E628 and R657: After installing this cell, connect via USB and allow a full charge before first use. Digma's firmware recalibrates the battery percentage gauge against a complete charge cycle — skip this step and the indicator will report incorrect levels until you complete one full charge.

Why the E628 shows incorrect battery percentage after a cell swap

The E628 stores charge curve data from the original cell in firmware memory. When you swap in a new cell, that stored profile no longer matches actual cell behaviour. The gauge reads from a stale reference until the firmware runs a full charge-discharge recalibration cycle. To clear the mismatch, charge the device to 100% without interruption, then use it down to auto-shutoff once. After that single cycle, percentage readouts align to the new cell.

E628 not powering on at all after battery replacement

If the device shipped or sat in storage, the cell voltage may have dropped below the E628's minimum boot threshold — typically around 3.0V for this class of mainboard. The device will not attempt to boot below that floor, so a power button press does nothing. Connect a USB charger and leave it for at least 10 minutes before pressing the power button. Once the cell recovers above the boot threshold, the device will start normally.