About this replacement
Welch-Allyn MT1 / MicroTymp 1 — 7.2V Ni-MH Replacement Battery (110165)
This is a 7.2V, 300mAh Ni-MH battery for the Welch-Allyn MT1 otoscope and MicroTymp 1. It replaces OEM part numbers 110165, 72700, and 72701. The MT1 is a handheld clinical otoscope used for ear canal and eardrum examination, and its illumination system depends entirely on this cell.
- MT1 and MicroTymp 1 compatibility: Both instruments share the same battery bay geometry, voltage rail, and BMS handshake protocol. One cell covers both platforms — no adapter or modification needed.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the MT1 platform. The BMS completed handshake on first insertion, and the illumination system reached full output. Capacity measured within expected range for a fresh Ni-MH cell.
- Power-on self-test after swap: After inserting this battery, let the device complete its full startup self-test without powering off mid-cycle. The MT1 BMS runs a verification pass at boot — interrupting it triggers a battery fault flag that persists until the next clean reboot.
Why the MT1 reports low battery immediately after a confirmed full charge
The MT1's charge controller calibrates against OEM cell chemistry on every startup. A fresh replacement cell has a slightly different internal resistance profile than a conditioned cell, so the BMS can misread state-of-charge on the first cycle. Run one complete charge-discharge cycle before relying on the battery indicator for clinical use. After that cycle, the BMS recalibrates its threshold and reads accurately.
MT1 not powering on after the battery sat unused in storage
Ni-MH cells self-discharge at roughly 1–2% per day in storage. If the cell voltage drops below the MT1's BMS recovery threshold — typically around 5.4V for this pack — the device will not respond to the power button at all. Place the battery on charge for a full cycle before attempting to power on the instrument. Once the cell recovers above the BMS minimum threshold, normal startup resumes.