Welch-Allyn 211 Otoscope Replacement Battery 2.4V 800mAh

Welch-Allyn 211 Otoscope Series — 2.4V Ni-CD Replacement Battery (B11617)

This is a 2.4V 800mAh Ni-CD replacement battery for the Welch-Allyn 211 otoscope and related handles including the 72600, 72800, and 72801. It replaces OEM part numbers B11617, 72600, AB24667, and several cross-reference codes used across medical supply distributors. Physical dimensions are 104.62 x 15.82 x 14.58mm — verify against your handle cavity before ordering.

• 211 handle platform: The 211, 72600, 72800, and 72801 share the same cylindrical handle form factor, 2.4V voltage rail, and connector orientation. The BMS in these handles expects a Ni-CD cell profile — voltage rise on charge and a flat discharge curve. A different chemistry will either fail to charge or trigger a false low-battery fault.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a 211 handle. The BMS accepted the cell without fault codes, and the charge indicator progressed normally. Capacity matched rated 800mAh within acceptable tolerance at cycle three.
• First-use cycle on medical handles: After installing this cell, allow the otoscope to complete its power-on self-test without switching it off mid-sequence. The 211-series handle runs a BMS verification check at startup. Interrupting that check before it finishes causes a persistent battery fault flag that clears only on the next clean reboot.

Why the 211 handle reads low battery after a confirmed full charge

The 211 handle's charge IC was calibrated against an aged OEM cell with a worn voltage curve. A fresh Ni-CD cell charges to a slightly higher terminal voltage, and the BMS can interpret that unfamiliar profile as an anomaly on the first cycle. This causes a low-battery indication even when the cell is fully charged. One complete charge-discharge cycle recalibrates the BMS to the new cell's curve. After that first cycle, the indicator reads correctly.

Otoscope will not power on after the replacement cell sat unused in storage

Ni-CD cells self-discharge during storage — at a rate of roughly 1–2% per day, a cell stored for several months can drop below the BMS recovery threshold, typically around 1.0V per cell. When voltage falls that low, the handle's BMS will not initiate a charge cycle and the device appears completely dead. Place the cell on a standalone Ni-CD charger first to bring it above 2.0V total. Once it clears that threshold, reinstall it in the handle and charge normally.