About this replacement
Apple MacBook 12" Retina A1534 — 7.6V Li-Polymer Replacement Battery (A1527)
This 7.6V, 5200mAh (39.52Wh) Li-Polymer cell replaces the A1527 battery in the Apple MacBook 12" Retina A1534. It fits Early 2015 and Early 2016 configurations of this ultraportable. The connector, cell dimensions (268.94 × 156.18 × 6.84mm), and BMS communication protocol match the original specification.
- A1534 Early 2015 and Early 2016 compatibility: Both model years use the same A1527 cell format, voltage rail, and SMBus handshake. One replacement covers both without any hardware modification.
- Bench tested on actual hardware: We cycled this cell on an A1534 unit, confirming the BMS negotiates charge termination correctly at 8.4V and that the SMC does not flag an immediate service warning after the first full cycle.
- First-cycle calibration on the A1534: After fitting, run the MacBook on battery until it reaches hibernate cutoff, then charge uninterrupted to 100%. This gives the fuel gauge IC a clean baseline against the new cell and clears the inaccurate health alert macOS often shows after a cell swap.
Why macOS reports poor battery health immediately after fitting a new A1527 cell
The A1534 stores cycle count and health data in EEPROM on the original battery's BMS. When you install a replacement cell, macOS reads that stored data and may still display the old health rating for the first few cycles. This is a fuel gauge IC calibration issue, not a fault with the new cell. Running one complete discharge-to-hibernate followed by an uninterrupted full charge resets the learn cycle. After two to three cycles the health indicator in System Information will reflect the actual state of the replacement cell.
MacBook A1534 shutting down at 20–30% battery shown
This symptom means the fuel gauge IC has not yet mapped the new cell's voltage curve. The laptop's SMC uses the old discharge profile to predict remaining capacity, and when the cell voltage drops under combined CPU and display load, the voltage cliff arrives earlier than the gauge expects. The SMC interprets this as an emergency cutoff at what appears to be 20–30% remaining. Run two to three full discharge-to-100% cycles and the gauge will recalibrate. If it persists after three cycles, check coconutBattery and confirm cell voltage is reaching at least 8.2V at full charge before each test.