PocketBook 626 Compatible Battery 3.7V 1450mAh 306070PL

Pocketbook 626 / 615 / 627 / 632 Series — 3.7V Li-Polymer Replacement Battery (306070PL)

This is a 3.7V 1450mAh Li-Polymer replacement battery for the Pocketbook 626, 615, 627, and 632 e-readers, along with eleven additional compatible models. It matches the original cell's voltage, capacity, and physical footprint. Part numbers 306070PL, 4G-15, and 4K-19 all cross-reference to this same cell.

• Multi-model fit across the 600 series: These Pocketbook models share the same battery bay dimensions, 3.7V power rail, and connector pinout. The BMS on each device communicates over the same interface, so one cell covers the full range without modification.
• Bench tested on actual hardware: We ran this cell through a full charge and discharge cycle on a 626 unit. The BMS accepted the cell without error, voltage held steady through the e-ink refresh cycles, and the charge curve matched the original cell's profile.
• Post-swap charge cycle on Pocketbook firmware: After fitting this battery, connect to USB and allow a complete charge before powering on. Pocketbook firmware recalibrates the percentage gauge against a full charge cycle — skipping this step causes the display to show an inaccurate state-of-charge from the first boot.

Battery percentage jumping around after fitting a new cell

Pocketbook e-readers store charge calibration data tied to the original cell's discharge curve. When a new cell is fitted, the firmware has no reference point and reads voltage directly — which does not map cleanly to percentage until it learns the new cell. The gauge stabilises after one or two full charge-to-discharge cycles. Do not judge the replacement by the first readout; let it complete a full cycle from 100% down to the automatic low-battery shutdown, then recharge fully.

E-reader powers on but shuts down within seconds of leaving the charger

This happens when the cell ships at storage voltage — typically around 3.6V — which sits below the threshold the Pocketbook firmware requires to sustain normal operation without USB power present. The device boots, checks available voltage, and cuts off as a protection measure. Connect the USB cable, leave it charging for at least 20 minutes before attempting to use it off-charger, and wait until the on-screen indicator shows above 3.9V or the battery icon shows at least one bar of charge before disconnecting.