Mackwell BH164 Emergency Light Replacement Battery 2.4V 3800mAh

Mackwell BH164 Series — 2.4V Ni-MH Replacement Battery (MGH9013)

This is a 2.4V, 3800mAh Ni-MH replacement cell for Mackwell emergency lighting units. It fits the BH164 and related models including 2QQMH4-0-CP, 2QQMH4-0LFT4, and 2QQMH40CP. It replaces OEM part MGH9013 and cross-references TBS-B902 and B902.

• BH164 platform compatibility: These models share a common 2.4V battery bay, connector pinout, and charge controller float voltage. One cell specification covers the full BH164 cluster without modification.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and confirmed the BMS accepted the charge without triggering a fault flag. Cell voltage at rest settled within the float acceptance window the charge controller expects.
• First cycle after installation: Within 24 hours of fitting, hold the test button for the full rated duration. This confirms the cell accepts load under real conditions and lets the charge controller register the new cell before your next scheduled compliance test.

Emergency light failing its duration test after battery replacement

A freshly installed Ni-MH cell often has not reached full capacity when it first comes off storage. The charge controller in the BH164 fitting applies a trickle float charge — it does not run a rapid conditioning cycle. This means the cell may only hold 60–70% of rated capacity on the first test if it has not had at least 24 hours of uninterrupted charge before the test button is pressed. Run one full charge cycle, then hold the test button to complete a full duration discharge before the compliance test date.

Charge indicator staying red after new battery installation

The BH164 charge controller checks that incoming cell voltage sits within a narrow acceptance window before switching the LED from red to green. A cell that has self-discharged during storage may arrive below that threshold — typically under 2.0V for a 2.4V Ni-MH pack. The controller reads this as a fault condition rather than a low cell. Leave the fitting powered for 12–24 hours; once the trickle charge raises cell voltage above the acceptance floor, the LED will transition to green without any manual reset.