About this replacement
Razer Blade 15 2020/2021 — 15.4V Li-Polymer Replacement Battery (RC30-0328)
This is a 15.4V, 4200mAh (64.68Wh) Li-Polymer replacement battery for the Razer Blade 15 2020 and 2021 series, including RZ09-0330x and RZ09-03305x variants. It replaces OEM part RC30-0328 when the original cell degrades or fails to hold charge. Fits the standard battery bay without modification.
- RZ09-0330x and RZ09-03305x compatibility: These Blade 15 variants share the same 15.4V battery rail, physical footprint, and connector pinout as the 2020 base model — the RC30-0328 part number covers all of them from the factory.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Blade 15 2020 unit. The BMS accepted the new cell without fault codes, and the charge controller advanced through each stage correctly to 100%.
- Post-install discharge cycle: After fitting, run the laptop on battery until it hibernates at low-cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell data and clears the inaccurate health warning that appears after every cell swap.
Why the Blade 15 shuts down at 20–30% after a battery swap
The Blade 15 fuel gauge IC builds a discharge map against the old cell's internal resistance profile. After a swap, that map no longer matches the new cell's voltage curve, so the system reads an early voltage cliff and triggers an emergency shutdown. The fix is calibration — not a faulty battery. Run two to three full discharge-to-hibernate and uninterrupted-charge cycles. After that, the fuel gauge IC recalibrates its endpoint model and the shutdowns stop.
BIOS reporting battery health as poor immediately after fitting a new cell
The Blade 15 BIOS reads health data from EEPROM registers that were written by the original cell's charge history. A new cell arrives with fresh cycle counts and different EEPROM state, which the BIOS interprets as a mismatch and flags as poor health. This is a reporting artefact, not a hardware fault. Complete the full discharge-to-hibernate cycle described above — once the BIOS battery learn cycle finishes, the health status corrects to normal.