Compaq Presario B1800 Compatible Battery 11.1V 4400mAh

Compaq Presario B1800 Series — 11.1V Li-ion Replacement Battery (397164-001)

This is an 11.1V, 4400mAh (48.84Wh) Li-ion replacement battery for the Compaq Presario B1800 series notebook. It fits the B1800, B1801TU, B1802TU, B1803TU, and over 18 additional B1800 variants sharing the same battery bay and connector. OEM part numbers covered include 397164-001, W22044LB, HSTNN-A14C, EH510AA, and W22045LF.

• B1800 series compatibility: Every B1800-series variant on the fit list uses the same 11.1V three-cell configuration, identical connector pinout, and the same BMS handshake protocol — so one SKU covers the full range without modification.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and load test on a B1802TU. The BMS engaged correctly at charge cutoff, balancing across all three cell groups, and the protection circuit tripped as expected under a simulated short-load event.
• First-cycle reset on the B1800: After installing, run one full discharge down to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that almost always appears after a cell swap on this platform.

Why the Presario B1800 BIOS reports poor battery health after a cell swap

The B1800 BIOS stores charge history and health data in EEPROM on the old battery's fuel gauge IC. When a new cell goes in, that EEPROM data is gone — the BIOS reads an empty or mismatched register and flags the battery as unknown or degraded. This is not a fault with the replacement cell. Running one complete discharge-to-hibernate followed by a full uninterrupted charge gives the BIOS enough data to recalibrate. After two to three full cycles, the health indicator and estimated charge figures stabilise.

Presario B1800 shutting down at 20–30% charge remaining

This happens when the fuel gauge IC hasn't been calibrated against the new cell's actual chemistry. The OS reads a voltage curve mapped to the old, degraded cell — so it hits its shutdown threshold well before the new cell is actually empty. The fix is to let the laptop discharge fully to the BIOS-triggered hibernate point, not a manual shutdown. Charge back to 100% without interruption. Repeat two cycles and the fuel gauge IC re-maps to the correct voltage cliff, typically around 9.9V under load.