About this replacement
Edan F6 / F9 Series Patient Monitor — 14.4V Li-ion Replacement Battery (TWSLB-006)
This is a 14.4V, 6800mAh Li-ion replacement battery for the Edan F6 and F9 series portable patient monitors, including the F6 Fetal Monitor and F9 Fetal Monitor variants. It replaces OEM part numbers TWSLB-006, HYLB-854, and 4IXR19/65-2. Use it to restore untethered monitoring capability when the original battery no longer holds a full charge.
- F6 and F9 series compatibility: These models share a common 14.4V battery platform, connector footprint, and BMS communication protocol. The same cell pack and protection circuit board satisfies the handshake each variant expects at power-on.
- Bench tested on actual hardware: We cycled this cell through a full charge and discharge on the F6 monitor. The BMS reported correct cell voltage, passed the device's internal self-test routine, and did not trigger any battery fault codes.
- Post-installation self-test protocol: After fitting this battery, let the monitor complete its full power-on self-test without interruption. The F6 and F9 run a BMS verification sequence at startup — cutting power during this window registers a false battery fault that persists until the device is fully rebooted and the sequence runs again from scratch.
Why the F6 alarms low battery immediately after a confirmed full charge
The F6's charge IC applies a conservative acceptance threshold calibrated to an OEM cell with known charge history. A new cell has no prior cycle data in the BMS memory, so the monitor reads capacity conservatively and can flag a low-battery condition even when the cell is fully charged. This resolves after one complete charge-discharge cycle, which allows the BMS to characterise the new cell's actual capacity. Run that first cycle before returning the device to clinical use.
F6 or F9 monitor will not power on after the replacement battery sat in storage
Li-ion cells self-discharge during storage. If the cell voltage has dropped below approximately 2.5V per cell — around 10V pack voltage — the BMS enters a deep-discharge lockout and blocks output to protect the cells. The device will show no response at the power button. Connect the monitor to mains power and leave it on charge for a minimum of 30 minutes before attempting to power on; this allows the charge IC to trickle-charge the pack back above the BMS recovery threshold, typically 3.0V per cell.