About this replacement
Lenovo Yoga Slim 7 ProX 14IAH7 / 14ARH7 — 15.52V Li-Polymer Replacement Battery (L21C4PC4)
This 15.52V, 4450mAh (69.06Wh) Li-Polymer battery replaces the original L21C4PC4, L21D4PC4, L21D4PE0, and L21L4PC4 cells found in the Lenovo Yoga Slim 7 ProX and Yoga Slim 7 Pro 14-inch series. It fits the 82TK and 82TL chassis variants, including the 82TK0076MX, 82TL003TKR, 82TK0025IN, and 82SV00AJCL, among 121 additional model codes. Voltage, connector pinout, and BMS communication lines match the original specification.
- Yoga Slim 7 ProX / 7 Pro 14-inch compatibility: The 82TK, 82TL, and 82SV chassis all run the same 15.52V power rail with an identical 4-pin SMBus connector. The BMS handshake protocol across these models accepts the same EEPROM identifiers, so the battery registers correctly in Lenovo Vantage and the firmware without modification.
- Bench tested on actual hardware: We cycled this cell on an 82TK unit, monitoring BMS communication, charge acceptance, and cutoff behaviour under sustained CPU and display load. The cell reached full charge acceptance and the BMS reported state-of-charge accurately within three cycles.
- Post-install learn cycle on the Yoga Slim 7 ProX: After fitting this battery, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. The Yoga Slim 7 ProX uses a BIOS-level battery learn cycle — skipping this step leaves the fuel gauge IC calibrated against the old cell's data, which triggers inaccurate health warnings in Lenovo Vantage.
BIOS reporting poor battery health immediately after fitting a new cell
The Lenovo BIOS reads health data from the battery's EEPROM, not from live voltage measurements. When a new cell is installed, the EEPROM carries rated factory values that don't match the BIOS's stored history for the previous cell, so the firmware flags the battery as degraded or unknown. This is not a fault with the replacement cell. Run one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100% — the BIOS learn cycle re-writes the reference data against the new cell's actual chemistry. After two to three cycles, the health indicator in Lenovo Vantage should clear.
Laptop shuts down at 20–30% charge shown after battery swap
This happens when the fuel gauge IC is still calibrated against the old, degraded cell's voltage curve. The new cell's voltage at 20–30% state-of-charge sits higher than the old cell's equivalent point — but the IC interprets that voltage as nearly depleted and triggers shutdown. The fix is a full discharge-to-hibernate sequence: let the laptop run on battery with screen at full brightness until it hibernates automatically, then charge to 100% without interruption. Repeat this once more if the gauge is still drifting — by the second cycle the IC recalibrates and the 15.52V cutoff threshold maps correctly to the new cell.