About this replacement
Biomedical Crossvent 3+ / 4+ — 7.2V Ni-MH Replacement Battery (PRT4467 / B11470)
This 7.2V 5000mAh Ni-MH battery replaces the internal power cell in the Biomedical Crossvent 3+ and Crossvent 4+ portable ventilators. It fits both models using OEM part numbers PRT4467 and B11470. Capacity figure is taken directly from product specification — 36Wh.
- Crossvent 3+ and 4+ shared platform: Both models run the same 7.2V battery rail with an identical connector and BMS handshake protocol. One cell fits both units because Biomedical standardised the power architecture across this ventilator generation.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Crossvent platform. The BMS accepted the cell, completed voltage verification, and cleared the low-battery alarm flag after one full charge cycle.
- Post-swap self-test protocol: After installing this battery, allow the Crossvent to complete its full power-on self-test without interruption. The device BMS runs a chemistry verification sequence at startup — cutting power during this window logs a false battery fault that persists until the next clean reboot.
Low battery alarm firing immediately after a confirmed full charge
The Crossvent BMS stores threshold parameters calibrated to the original OEM cell's charge curve. A new Ni-MH cell has a slightly different internal resistance profile until it completes its first full cycle. The BMS reads this as a below-threshold state-of-charge and triggers the alarm even when the cell is fully charged. Run one complete charge-discharge cycle before clinical deployment. After that cycle, the BMS recalibrates and the alarm clears at normal voltage levels.
Ventilator fails to power on after the replacement cell sat in storage
Ni-MH cells self-discharge during storage. If the cell voltage drops below approximately 6.0V, the Crossvent BMS enters a protection state and blocks startup to prevent damage. The device will appear completely dead — no display, no boot sequence. Connect the Crossvent to mains power and leave it on charge for a minimum of four hours before attempting to power on. This allows the charge IC to recover the cell voltage above the BMS recovery threshold.