Brady 41-BP Portable Label Printer Replacement Battery 10.8V 1200mAh

Brady BMP41 / BMP61 — 10.8V Ni-MH Replacement Battery (41-BP)

This is a 10.8V, 1200mAh Ni-MH replacement battery for the Brady BMP41 and BMP61 portable label printers. It replaces OEM part number 41-BP and slots into the same battery bay without modification. Voltage and cell chemistry match the original spec exactly.

• BMP41 and BMP61 compatibility: Both printers run on the same 10.8V Ni-MH battery platform and share the 41-BP form factor, connector pinout, and BMS communication protocol — the same cell works across both units without firmware conflict.
• Bench tested on actual hardware: We ran this battery through charge and discharge cycles on the BMP41 platform. The BMS accepted the new cell, completed charge termination correctly via delta-V detection, and thermal head draw stayed within spec throughout the print cycle.
• First-use print sequence: After installing this battery, charge it fully before printing. Then run five consecutive test labels before field deployment — the BMP41 print head motor draws a calibration-level current on initial cycles, and the BMS needs those cycles to correctly profile current load against cell capacity.

Why the BMP41 refuses to power on after sitting unused for weeks

Ni-MH cells self-discharge at roughly 1–3% per day at room temperature. A BMP41 left unused for three to four weeks can return a resting voltage below the printer's minimum boot threshold. The BMP41 bootloader checks battery voltage before initialising the print head — if the cell sits below roughly 9.0V, the unit will appear completely dead. Connect the printer to its charger and leave it for at least 30 minutes before attempting to power on; the charger applies a recovery trickle that brings the cell back above boot voltage.

Print coming out faded or streaky on a charged battery

The BMP41 thermal print head requires a steady voltage rail to maintain consistent head temperature across the full print width. A degraded or partially charged Ni-MH cell causes voltage sag the moment the head fires, dropping below the level needed for uniform heat output — the result is faded text, missing segments, or streaky lines even when the battery indicator shows charge remaining. This is not a head or ribbon fault. Charge the battery fully to 10.8V, then re-run the print job — if the output is still inconsistent, the cell has degraded and capacity no longer matches the OEM spec.