KAPOK Compaq Presario 7200 Replacement Battery 12V 3800mAh

KAPOK Compaq Presario 7200 Series — 12V Ni-MH Replacement Battery (DR36)

This is a 12V, 3800mAh Ni-MH replacement battery for the Compaq Presario 7200 series laptop. It also fits the 6200M, 6100, and 7800 series notebooks. OEM part numbers DR36 and DR36S are both covered by this cell.

• Presario 6100, 6200M, 7200, and 7800 compatibility: These models share the same 12V power rail, battery bay connector, and BMS handshake protocol — one cell fits the full range without any adapter or wiring change.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Presario 7200 unit. The BMS accepted the new cell without fault codes, and the charge controller completed a full charge cycle without interruption.
• First-cycle calibration on Ni-MH cells: After installing, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. Ni-MH cells need this cycle to reset the BIOS battery learn routine — skipping it leaves an inaccurate health warning in the OS that persists across reboots.

BIOS reporting battery health as poor after replacing the DR36 cell

The BIOS stores battery health data in EEPROM from the previous cell. When a new cell goes in, that stored data does not clear automatically — the BIOS compares the new cell's output against old reference values and flags a mismatch as poor health. This is not a fault with the replacement cell. Running one complete discharge-to-hibernate then a full uninterrupted charge triggers the battery learn cycle and rewrites the EEPROM reference data. After that cycle completes, the health status updates to reflect the actual condition of the new cell.

Fuel gauge jumping between readings and showing wildly wrong percentages

The fuel gauge IC in these Presario models estimates charge state by tracking voltage curves it learned from the old cell. A fresh Ni-MH cell has a different internal resistance and voltage slope, so the IC miscalculates and displays erratic percentages for the first few cycles. This is a calibration gap, not a hardware fault. Run two or three full discharge-to-hibernate and full-charge cycles without interruption. By the third cycle the IC has enough data to track the new cell accurately, and the gauge stabilises to within a few percent.