About this replacement
Acer Nitro 5 AN515-43 Series — 15.4V Li-Polymer Replacement Battery (AP18E8M)
This is a 15.4V, 3700mAh (56.98Wh) Li-Polymer battery for the Acer Nitro 5 and Aspire 5 laptop lines. It replaces OEM part numbers AP18E8M, AP18E7M, KT.00407.007, and KT00407009. It fits the AN515-43, AN515-54, and AN517-51 series, among 340 additional Acer models sharing the same battery bay and connector spec.
- AN515 and AN517 series fit: These Nitro models share a common 15.4V four-cell battery rail, the same ZH1.25 connector pinout, and an identical BMS handshake protocol — which is why one SKU covers the full range without modification.
- Bench tested on actual hardware: We cycled this cell on an AN515-54 chassis. The BMS accepted the new cell on first boot, reported charge current correctly through the EC, and held voltage above 14.8V through a sustained CPU-plus-GPU load draw.
- Post-install calibration on Nitro 5: After fitting, run the laptop down to hibernate cutoff under normal use, then charge uninterrupted to 100%. This single cycle resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the Nitro 5 shuts down at 20–30% after a battery swap
The Nitro 5 EC uses stored discharge curves from the old cell to predict cutoff voltage. With a new cell installed, those curves no longer match actual cell chemistry, so the EC triggers a shutdown well before the cell is depleted. The symptom looks like a faulty battery but is entirely a calibration issue. Running two full discharge-to-hibernate cycles forces the EC to rebuild its fuel map against the new cell. After that, the gauge and cutoff threshold track correctly.
BIOS showing battery health as "poor" immediately after fitting a new cell
The Acer BIOS reads health data from EEPROM registers inside the battery's BMS — not from live voltage measurements. When a replacement cell ships, those registers reflect factory defaults, not a full charge history, and the BIOS flags this as degraded. This is not a fault with the cell. Complete one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100%. The BIOS battery health indicator will update after the learn cycle completes and the register values normalise.