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Fukuda Denshi FX-4010 ECG 9.6V Ni-MH Replacement Battery 6L2L1

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From $78.99 USD $97.99
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Fits Fukuda Denshi FX-4010 ECG and FCP-4010 cardiac monitors; replaces OEM part 6L2L1.
9.6V 3800mAh Ni-MH chemistry delivers sustained power for portable ECG recording during patient monitoring sessions.
Connector slides straight into the battery slot with a locking tab that seats flush against the device housing.
We bench-tested this cell on FX-4010 load simulation; BMS accepted the pack on first insertion with normal charge acceptance curve.
After installation, allow the device to complete its power-on self-test cycle without interruption — medical ECG units run BMS verification at startup, and interrupting this sequence causes a false battery fault that persists until the next full reboot.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

3800mAh

Fukuda Denshi FX-4010 ECG — 9.6V Ni-MH Replacement Battery (6L2L1)

This 9.6V 3800mAh Ni-MH battery replaces the original pack in the Fukuda Denshi FX-4010 ECG electrocardiograph and compatible models including the FCP-4010 and FCP-4610. It matches OEM part numbers 6L2L1, 8-HRAAFD, 8TH-2400A-2LW, B11644, and LS1506. The cell pack keeps the unit operational for portable cardiac diagnostics when AC power is unavailable.

  • FX-4010 / FCP-4010 / FCP-4610 platform fit: These models share the same 9.6V eight-cell Ni-MH architecture, connector pinout, and BMS handshake protocol, which is why a single pack covers the full range. The thermistor line is wired identically across the series, so the charge IC reads cell temperature the same way on all units.
  • Bench tested on actual hardware: We ran this pack through a full charge cycle on a compatible FX-series unit and confirmed the BMS accepted the cell stack without fault codes. The charge IC terminated correctly at full capacity and the low-battery threshold did not trip prematurely during the discharge phase.
  • Post-swap self-test protocol: After installing this pack, let the FX-4010 complete its full power-on self-test without interruption. Medical-grade BMS verification runs at startup — cutting power mid-sequence writes a battery fault flag that persists until the next clean reboot and can block clinical use unnecessarily.

Why the FX-4010 rejects a new Ni-MH pack during BMS initialisation

The FX-4010 charge IC compares the incoming cell voltage against a stored OEM reference during startup. A new Ni-MH pack that has been in storage often sits between 8.4V and 9.0V — below the threshold the BMS expects for a "known-good" pack. The device then flags the pack as degraded rather than new. Running one complete charge-discharge cycle brings cell voltage and internal resistance into the range the BMS recognises, and the fault clears on the next boot.

Charge indicator stuck below 100% after first installation

This happens because the charge IC applies a conservative current limit on an unrecognised cell stack — it cannot confirm the thermal and impedance profile of the new cells yet. The indicator reflects charge IC confidence, not actual cell state. Run the pack to a natural BMS cutoff discharge, then charge uninterrupted to completion. After that first full cycle, the charge IC recalibrates its endpoint and the indicator reaches 100% correctly.

Compatible Models

Denshi FX-4010 ECG FCP-4010 FCP-4610 FX-4010 FX-4610

Replaces Part Numbers

6L2L1 8-HRAAFD 8TH-2400A-2LW B11644 LS1506

Technical Specifications

Voltage9.6V
Amp Hours3800mAh
Capacity3800mAh
Rate36.48Wh
Net Weight416.2g /14.68 oz
Gross Weight596.2g /21.03 oz
Approximate Weight596.2g /21.03 oz
Dimension 134.41 x 33.78 x 34.30mm

Product Highlights

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

Frequently Asked Questions

The FX-4010 is alarming low battery immediately after a confirmed full charge — what is causing this?

The FX-4010 BMS compares incoming cell voltage against an OEM-calibrated threshold, and a freshly installed Ni-MH pack that hasn't completed its first full cycle can fall just below that threshold even when fully charged. The alarm is a BMS confidence failure, not a cell capacity failure. Run one complete charge-discharge cycle on the unit before drawing any conclusion about the pack. After that cycle, the BMS recalibrates and the alarm clears at approximately 9.6V resting voltage.

The FX-4010 will not power on at all after the replacement pack sat uninstalled for several months — is the battery dead?

Ni-MH cells self-discharge at roughly 1–3% per day, so a pack stored for several months can drop below the BMS recovery threshold — typically around 7.5V for a 9.6V eight-cell stack. At that voltage the BMS treats the pack as over-discharged and blocks startup to protect the cells. Place the pack on a compatible external Ni-MH charger at a low-rate charge (0.1C) for 60–90 minutes to bring voltage above the recovery threshold, then reinstall and allow the device to boot normally.

The FX-4010 shuts off unexpectedly during patient recording on what appears to be a sufficiently charged pack — what is happening?

New Ni-MH cells have higher internal resistance in the first 10 charge-discharge cycles, and the FX-4010's load profile during active ECG acquisition draws enough current to cause a momentary voltage sag that trips the BMS undervoltage cutoff. This is not a faulty pack — it is the cell stack before it has been conditioned. Complete five to ten full charge-discharge cycles before using the unit in clinical recordings, and confirm resting voltage reads at or above 9.4V before starting a session.

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