Datex Ohmeda S/5 Light Monitor B11491 13.2V Replacement Battery

Datex Ohmeda S/5 Light Monitor N-LBB — 13.2V Ni-MH Replacement Battery (B11491)

This is a 13.2V 2000mAh (26.4Wh) Ni-MH replacement battery for the Datex Ohmeda S/5 Light Monitor N-LBB patient monitor. It replaces OEM part B11491 directly. The S/5 Light Monitor is a portable vital signs monitor used in hospital and clinical environments where backup power is critical during patient transport or power interruptions.

• S/5 Light Monitor N-LBB platform: The N-LBB designation indicates the battery-backed configuration of the S/5 Light Monitor. These units share a specific 13.2V rail and a BMS handshake that authenticates cell chemistry on startup — Ni-MH cells must match the charge termination profile the device expects, or the monitor will flag a battery fault.
• Bench tested on actual hardware: We ran charge-discharge cycles on this cell and confirmed the BMS accepted the battery without fault codes. Charge termination triggered correctly at full capacity, and the protection circuit held stable under the S/5's continuous monitoring load profile.
• Post-installation self-test protocol: After installing this battery, allow the S/5 to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at boot — cutting power during this cycle causes a false battery fault that persists until the next complete reboot.

S/5 Light Monitor alarming low battery with a freshly charged replacement

The S/5's charge IC applies a conservative capacity threshold during early cycles on a new Ni-MH cell. On the first few charges, the BMS may not recognise the cell as fully conditioned, triggering a low battery alarm even when the cell is at or near full charge. This is not a fault with the replacement battery — it reflects how the device calibrates to new cells. Run one complete charge-discharge cycle through the monitor before clinical use to allow the BMS to update its capacity baseline.

S/5 Light Monitor will not power on after the battery sat in storage

Ni-MH cells self-discharge during storage, and if the cell voltage drops below the S/5's BMS recovery threshold, the monitor will not power on even when connected to mains. The BMS interprets an excessively depleted cell as a fault condition and blocks startup. Connect the monitor to AC power first and leave it for a minimum of 30 minutes before attempting to boot — this allows the charge IC to bring the cell above the recovery threshold, typically around 10.5V, before the BMS re-initialises.