About this replacement
Razer Book 13 Series — 11.55V Li-Polymer Replacement Battery (RC30-0357)
This 11.55V, 4700mAh (54.29Wh) Li-Polymer battery is a direct cell replacement for the Razer Book 13 ultrabook lineup. It fits the Book 13 Core i7, Book 13 FHD, and Book 13 UHD Touch 2020, all sharing OEM part numbers RZ09-0357 and RC30-0357. Voltage and connector pinout match the original pack exactly.
- Book 13 FHD, UHD Touch, and Core i7 compatibility: These three variants share the same battery bay dimensions (272.90 × 101.55 × 5.20mm), the same 11.55V nominal rail, and the same BMS communication protocol — which is why Razer used one part number across the range.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the Book 13 platform. The BMS handshake completed without errors, charge termination triggered correctly at full capacity, and no false low-battery cutoffs occurred under sustained CPU and display load.
- First-cycle recalibration on the Book 13: After fitting this cell, run the laptop down to hibernate-cutoff on battery, then charge uninterrupted to 100% before unplugging. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears in Razer Synapse or Windows after every cell swap.
BIOS reporting poor battery health immediately after fitting a new cell
The Book 13 BIOS reads health data from EEPROM stored on the battery pack — not from a live measurement of the new cell. When you swap the cell, the BIOS still sees the old EEPROM profile and flags the battery as degraded. This is not a fault with the replacement cell. Running one full discharge-to-hibernate followed by an uninterrupted full charge forces the firmware to rewrite the learn cycle against the new cell's actual characteristics. After one or two cycles, the health status clears.
Laptop shuts down at 20–30% charge shown on the gauge
This happens when the fuel gauge IC has not yet calibrated against the new cell's discharge curve. The gauge was mapped to the old degraded cell and the percentage readout no longer matches actual remaining voltage. Under combined CPU and display load, the real cell voltage drops faster than the stale calibration predicts, and the system hits the low-voltage protection threshold while the gauge still shows 20–25%. Complete two full discharge-to-hibernate and full charge cycles to let the fuel gauge IC remap its curve. After calibration, the shutdown point should track accurately down to approximately 10.5V under load.