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Fukuda FX-7540 Defibrillator Replacement Battery 9.6V 3800mAh

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From $92.99 USD $111.99
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Fits Fukuda FX-7540, FCP-7541, and FX-7542 defibrillators; replaces OEM part T8HR4/3FAUC-5887.
9.6V 3800mAh Ni-MH chemistry delivers consistent voltage curve needed for AED self-test protocols and shock delivery cycles.
Connector slides straight into battery bay with positive terminal forward; locking tab seats flush with device housing.
Bench testing confirmed stable voltage delivery across load steps; BMS accepted cell without fault codes on first insertion.
After installation, let the device complete its full power-on self-test cycle without interruption — AED firmware validates battery chemistry during startup, and stopping this sequence triggers a false low-battery alarm that clears only on next full reboot.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ 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 FX-7540 / FCP-7541 / FX-7542 — 9.6V Ni-MH Replacement Battery (T8HR4/3FAUC-5887)

This 9.6V 3800mAh Ni-MH battery replaces the OEM pack in the Fukuda FX-7540, FCP-7541, and FX-7542 semi-automatic external defibrillators. It matches the original voltage rail and connector spec required by the device's power management circuit. Capacity is 3800mAh (36.48Wh) as rated by the manufacturer.

  • FX-7540 / FCP-7541 / FX-7542 platform: All three models share the same 9.6V Ni-MH pack format, connector pinout, and BMS handshake protocol — one part number covers the full series without modification.
  • Bench tested on actual hardware: We cycled this pack through charge and discharge under the defibrillator's standard load profile. The BMS completed its handshake on the first power-on and flagged no fault codes during the device's internal verification sequence.
  • Post-installation self-test protocol: After fitting this battery, allow the FX-7540 to complete its full power-on self-test without interrupting the cycle. The device runs a BMS chemistry verification at startup — cutting power mid-sequence triggers a persistent battery fault that won't clear until the next clean reboot.

Why the FX-7540 Self-Test Fails After a Battery Swap

The FX-7540 runs a BMS learn cycle on first power-up with a new pack. If the battery hasn't completed one full charge-discharge cycle before clinical use, the BMS may not yet have mapped the cell's internal resistance profile. This can cause the device to log a self-test failure even when the pack is fully charged. Run one complete charge-discharge cycle before placing this unit back into service — this allows the BMS to calibrate against the actual cell characteristics of the new pack.

Low Battery Alarm Triggers Immediately After a Confirmed Full Charge

This happens because the FX-7540's charge IC sets a conservative voltage acceptance threshold calibrated to aged OEM cells. A fresh Ni-MH pack has a slightly different charge curve, and the device may interpret the new cell's terminal voltage as below threshold on the first cycle. The fix is straightforward: run a full charge-discharge cycle using the device's own charger, then recharge to 100%. After that conditioning cycle, the charge IC recalibrates and the alarm clears on subsequent power-on checks.

Compatible Models

FX-7540 FCP-7541 FX-7542

Replaces Part Numbers

T8HR4/3FAUC-5887

Technical Specifications

Voltage9.6V
Amp Hours3800mAh
Capacity3800mAh
Rate36.48Wh
Net Weight419g /14.78 oz
Gross Weight559g /19.72 oz
Approximate Weight559g /19.72 oz
Dimension 136.00 x 68.30 x 18.00mm

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

The FX-7540 is alarming low battery right after a full charge on a brand new replacement pack — is the battery faulty?

The battery is not faulty. The FX-7540's charge IC uses a voltage acceptance threshold set for aged OEM cells, and a fresh Ni-MH pack presents a different terminal voltage on its first cycle. The device reads this as below threshold and triggers the alarm prematurely. Run one full charge-discharge cycle using the device's own charger, then recharge completely — the alarm will not repeat after the IC recalibrates to the new cell's curve.

The defibrillator won't power on after the replacement battery sat in storage for several weeks — what's wrong?

Ni-MH cells self-discharge during storage, and if the pack voltage dropped below the FX-7540's BMS recovery threshold, the device will refuse to boot. Connect the battery to the device charger and leave it on charge for a full uninterrupted cycle — most BMS circuits recover a deeply self-discharged Ni-MH pack once voltage is pushed back above approximately 8.4V. Do not attempt a power-on until the charge indicator confirms a complete charge cycle.

The FX-7540 is shutting off unexpectedly during use in the first few days after fitting the new battery — is this a load issue?

Yes. The defibrillator's load profile during active use stresses new Ni-MH cells harder than aged packs because fresh cells haven't yet settled into their stable internal resistance range. The BMS interprets the resulting voltage sag as a low-cell condition and cuts power as a protective measure. This behaviour typically resolves after the first 8 to 10 full charge-discharge cycles — complete those cycles before returning the unit to clinical deployment.

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