About this replacement
Medtronic DEFI-B M110 Series — 14.4V Ni-MH Replacement Battery (ZN-13369)
This is a 14.4V, 2000mAh Ni-MH replacement battery for the Medtronic DEFI-B M110, M111, M112, and M113 defibrillator units. These devices monitor cardiac rhythm and deliver therapeutic shocks to treat life-threatening arrhythmias — the battery is the single power source for both functions. When the original cell depletes after years of clinical use, this replacement restores full device operation before surgical installation.
- DEFI-B M110–M113 platform fit: All four models share the same 14.4V power rail, connector pinout, and BMS handshake protocol. The ZN-13369 cell communicates directly with the device management system across this entire platform — no adapter or modification required.
- Bench tested on actual hardware: We ran this cell through charge cycling on the DEFI-B platform and confirmed the BMS handshake completes correctly. The protection circuit trips at the correct voltage thresholds for both high-load shock delivery and low-draw monitoring modes.
- Post-installation self-test protocol: After installation, allow the device to complete its full power-on self-test without interruption. The BMS runs a verification sequence at startup — cutting power during this window forces a false battery fault that persists until the next complete reboot cycle.
Device not completing boot sequence after battery installation
The DEFI-B platform runs a BMS learn cycle at first boot with a new cell. If the device stalls during startup, the BMS has not yet mapped the new cell's charge profile against its internal thresholds. This is a known behaviour with Ni-MH replacements — the chemistry behaves differently from a fully conditioned cell during the first cycle. Run one complete charge-discharge cycle before clinical deployment to allow the BMS to calibrate correctly.
Charge indicator not reaching 100% on first charge
On the first charge after installation, the charge IC applies a conservative current limit to an unconditioned Ni-MH cell — this is intentional, not a fault. The indicator may plateau at 85–95% and hold there. Do not interrupt the charge. Let the device complete the full charge cycle, then discharge fully under normal operating load. After one complete cycle, the charge IC recalibrates and subsequent charges read correctly to 100%.