About this replacement
Barnes & Noble NOOK Classic / BNRZ100 — 3.7V Li-ion Replacement Battery (BNRB1530)
This 3.7V, 1250mAh Li-ion cell replaces the original battery in the Barnes & Noble NOOK e-reader, model 005 (OEM part BNRB1530). It fits the NOOK Classic and BNRZ100 variants that share the same battery bay dimensions and connector. Capacity matches factory spec at 4.63Wh.
- NOOK 005, BNRZ100, and Classic compatibility: These models share the same 3.7V single-cell architecture, connector pinout, and BMS handshake protocol — that's why one cell covers all three. The e-ink controller and CPU draw from the same rail, so voltage tolerance is identical across the group.
- Bench tested on actual hardware: We ran this cell on a NOOK 005 unit and confirmed the BMS accepted charge without error flags, the low-battery cutoff triggered at the correct threshold, and the display stayed stable through repeated page turns at full draw.
- First-charge calibration after swap: After installing, charge via USB until the indicator shows full before powering on. The NOOK firmware uses the first full charge cycle to set its fuel-gauge baseline — skipping this step causes the battery percentage to read incorrectly from the first boot.
Why the NOOK 005 shows low battery immediately after a new cell is installed
Replacement cells ship at storage voltage — typically around 3.6V — which sits just above the NOOK's low-battery warning threshold. The firmware reads that resting voltage on first boot and flags it as nearly depleted before any charge measurement has occurred. This is a firmware read issue, not a faulty cell. Connect the device to USB power immediately after the first boot and let it charge fully before using it.
Battery percentage jumping around after a cell swap on the NOOK Classic
The NOOK's fuel gauge learns cell behaviour over charge and discharge cycles — after a swap, it has no history for the new cell. Until it completes two or three full cycles, percentage readings can jump from 80% to 40% with no load change. This is recalibration, not a defective battery. Run two complete charge cycles from under 10% to full, and the gauge will stabilise.