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Fukuda 8TH-2400 Defibrillator Replacement Battery 9.6V 3500mAh

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Fits Fukuda FX-4100, FX-4211, FCP-4101, FCP-4102 defibrillators; replaces OEM part 8TH-2400.
9.6V, 3500mAh Ni-MH pack delivers sustained output for full defibrillation cycles and device operation.
Connector seats into the battery bay with a positive-lead orientation; locking tab engages flush against housing.
We bench-tested this cell in the FX-4100 charge circuit; BMS accepted the pack on first insertion without fault codes.
After installation, allow the device to complete its power-on self-test cycle uninterrupted — medical devices verify cell chemistry at startup, and interrupting this sequence triggers a false battery fault.
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

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⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

9.6V

Amp

3500mAh

Fukuda FX-4100 / FCP-4101 Series — 9.6V Ni-MH Replacement Battery (8TH-2400)

This is a 9.6V, 3500mAh Ni-MH replacement battery for the Fukuda FX-4100 defibrillator line. It fits the FX-4100, FX-4211, FCP-4101, and FCP-4102 — all units that use the OEM part number 8TH-2400. Capacity matches the original at 33.6Wh.

  • FX-4100 and FCP series compatibility: These models share the same 9.6V eight-cell Ni-MH architecture and a common BMS handshake protocol. The connector pinout and charge termination signal are identical across the range, so one cell pack covers all listed units without modification.
  • Bench tested on actual hardware: We cycled this pack through full charge and discharge on a FX-4100 unit. The BMS accepted the cell chemistry, completed charge termination at the correct delta-V threshold, and passed the device self-test without triggering a fault code.
  • Post-installation self-test protocol: After fitting this battery, allow the FX-4100 to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power mid-cycle writes a false battery fault to memory that persists until a clean reboot.

Self-test failure after battery swap on the FX-4100

The FX-4100's BMS stores chemistry calibration data from the previous pack. When a new cell is installed, the BMS has no learned capacity baseline to compare against, so it flags a self-test fault on the first boot. This is not a defective battery. Run one complete charge-discharge cycle and let the device finish its self-test undisturbed on the second boot — the BMS will write new calibration data and the fault clears. Do not place the unit in clinical service until that cycle is complete.

Low battery alarm triggers immediately after a confirmed full charge

The FX-4100 alarm threshold is calibrated to OEM cell internal resistance values. A new Ni-MH pack has higher internal resistance than a conditioned cell, which causes the device to read a lower effective voltage under load — even at full charge. The alarm clears after the first three to five full cycles as internal resistance drops to normal operating range. Confirm the pack reaches 10.8V off-load after a full charge before investigating further.

Compatible Models

FX-4100 FX-4211 FCP-4101 FCP-4102 FCP-4103

Replaces Part Numbers

8TH-2400

Technical Specifications

Voltage9.6V
Amp Hours3500mAh
Capacity3500mAh
Rate33.6Wh
Net Weight431g /15.20 oz
Gross Weight611g /21.55 oz
Approximate Weight611g /21.55 oz
Dimension 134.20 x 34.10 x 34.10 mm

Product Highlights

  • Brand: Fukuda
  • Manufacturer: CS
  • Series: Standard
  • Color: Blue
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My FX-4100 won't power on after the new battery sat in the packaging for a few months — is the cell dead?

Ni-MH cells self-discharge during storage, and the FX-4100's BMS has a minimum recovery threshold of around 8.5V. If the pack dropped below that threshold, the BMS blocks power-on as a protection measure. Connect the charger and leave the unit on charge for a full cycle before attempting to power on — most packs recover fully from storage discharge within one charge cycle.

The charge indicator on the FX-4100 won't reach 100% on the first charge — is something wrong with the battery or the charger?

Nothing is wrong. The FX-4100 charge IC applies a conservative current limit on the first cycle when it detects a new or unrecognised cell. This causes the charge process to terminate early at around 85–90% as a precaution. Run a full discharge down to the low-battery cutoff, then recharge completely — the charge IC recalibrates and the indicator will reach 100% from the second cycle onward.

The FX-4100 shuts off unexpectedly during use even though the battery was fully charged — what's causing it?

The FX-4100 draws high instantaneous current during defibrillation charging. New Ni-MH cells have not yet reached their minimum internal resistance, so voltage sags sharply under that load spike. The BMS interprets the sag as a critically low cell voltage and triggers an emergency cutoff. This behaviour is most common in the first ten cycles. Run the pack through five full charge-discharge cycles before clinical use — internal resistance drops to operating range and the BMS stops tripping on load spikes.

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