About this replacement
Brady LS2000 Labeler — 12V Ni-MH Replacement Battery (55851)
This is a 12V 2000mAh Ni-MH replacement battery for the Brady LS2000 and LS2000 Labeler handheld label printers. It replaces OEM part numbers 55851 and LS2000-BP. The LS2000 is a portable, field-use printer — keeping a spare battery charged means uninterrupted labeling without returning to a docking station.
- LS2000 and LS2000 Labeler compatibility: Both variants share the same 12V battery platform, connector pinout, and BMS handshake protocol. One battery covers both configurations without modification.
- Bench tested on actual hardware: We cycled this battery through full charge and load discharge on an LS2000 unit. The BMS maintained steady current delivery through the paper feed motor and thermal print head simultaneously, with no cutoff events.
- First-cycle print sequence: After installing and fully charging, run five consecutive label prints before field deployment. The thermal head and feed motor draw variable current during warm-up; completing this sequence lets the BMS establish the correct current profile for the new cells.
Voltage sag during thermal print head warm-up on the LS2000
The LS2000 thermal head draws its highest current in the first two seconds of a print job, when the head temperature ramps from ambient to operating range. A degraded or deeply discharged Ni-MH cell cannot sustain the voltage under this load spike, causing the printer to stall or produce a blank first label. A fresh, fully charged 12V 2000mAh cell holds the voltage rail above the 10.8V minimum the printer's power management circuit requires during that spike. If print quality recovers on the second or third label, the issue is an underpowered first draw — not a head fault.
LS2000 powering off mid-label run after sitting unused
Ni-MH cells self-discharge at roughly 1–3% per day at room temperature. An LS2000 left on a shelf for several weeks can reach a state-of-charge too low for the BMS to authorise motor and head current, even if the battery indicator shows partial charge. The printer may power on, begin feeding, then cut off before the label completes. Charge the battery fully — confirmed by the charger's ready indicator — then let it rest 10 minutes before the first print job to allow cell voltage to stabilise above 12V.