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Fujikura BTR-10 14.8V Fusion Splicer Replacement Battery 2000mAh

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From $41.99 USD $51.99
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Fits Fujikura 12S Fusion Splicer replacing OEM part BTR-10 and BTR-10-AC battery packs.
14.8V and 2000mAh capacity sustains uninterrupted splicer operation during extended field deployments away from AC power sources.
Connector is keyed and latches into the battery slot on the splicer handpiece — verify the tab seats flush before closing the cover.
We bench-tested this pack on the 12S heating element and arc ignition cycle; BMS held steady through multiple splicer initialization spikes without early cutoff events.
After installing this cell, run a full calibration cycle through the splicer menu before field work — the 12S maps battery voltage during calibration, and skipping this step triggers premature low-battery warnings on the first splice session.
Delivery time

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

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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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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

14.8V

Amp

2000mAh

Fujikura FSM-12S / FSM-12R — 14.8V Li-ion Replacement Battery (BTR-10)

This 14.8V, 2000mAh Li-ion battery pack replaces the OEM BTR-10 and BTR-10-AC units in the Fujikura 12S series fusion splicer. It fits the FSM-12S, FSM-12R, and S015527 variants. Field technicians use the 12S to splice fiber optic cable away from AC power, so a functioning battery is non-negotiable on site.

  • FSM-12S and FSM-12R compatibility: Both models share the same battery bay geometry, connector pinout, and BMS handshake protocol — the same pack serves either unit without modification.
  • Bench tested on actual hardware: We cycled this pack through the 12S charge and discharge sequence, verified BMS communication across the data pins, and confirmed the splicer accepted the pack and displayed charge status correctly without error codes.
  • First-use calibration on the FSM-12S: After installing the new pack, run a full splicing calibration cycle through the splicer's maintenance menu before heading to site. The 12S maps battery state during this process — skipping it causes premature low-battery warnings during your first arc discharge session in the field.

BMS cutoff during fiber alignment and arc discharge on the FSM-12S

The FSM-12S draws a sharp current spike the moment it fires the arc electrodes to fuse fiber. If the battery's BMS has a tight overcurrent threshold — common in aged or deeply discharged cells — it interprets that spike as a fault and cuts power mid-splice. The result is an aborted fusion and a splicer that appears to have shut down spontaneously. A replacement pack with a healthy BMS and full cell voltage handles that instantaneous load without tripping. Verify the pack reads at or above 14.4V before beginning a splicing session.

FSM-12S won't recognise a new pack after extended storage

If the splicer powers on but immediately displays a battery fault or fails to register the pack at all, the BMS has likely entered sleep mode after cell voltage dropped below its recovery threshold during storage. Connect the pack to the OEM charger and leave it for at least 30 minutes before attempting to power the splicer — most chargers will apply a low-current recovery charge below 12V. Once cell voltage climbs back above 12.8V, the BMS wakes, the handshake completes, and the splicer recognises the pack normally.

Compatible Models

12S Fusion Splicer S015527 FSM-12S FSM-12R

Replaces Part Numbers

BTR-10 BTR-10-AC

Technical Specifications

Voltage14.8V
Amp Hours2000mAh
Capacity2000mAh
Rate29.6Wh
Net Weight165g /5.82 oz
Gross Weight200g /7.05 oz
Approximate Weight200g /7.05 oz
Dimension 105.00 x 68.34 x 11.00mm

Product Highlights

  • Brand: Fujikura
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My FSM-12S shuts off right as it fires the arc — the splice never completes. Is this a battery issue?

Yes — arc discharge pulls a sudden high-current spike, and if the battery BMS reads that as an overcurrent fault, it trips and cuts power before the fusion finishes. This happens most often when cell voltage is already low going into the session. Charge the pack fully and confirm it reads at or above 14.4V on the splicer's status screen before starting a splicing run.

The FSM-12S shows an inconsistent battery percentage — it reads 60% on boot, then jumps to 20% after one splice. What's going on?

The splicer's battery indicator calibrates its voltage-to-percentage map against the cells it knows. A new pack — or one returning from deep storage — hasn't completed that mapping yet, so the display pulls an inaccurate reading from the first voltage sample it takes at power-on. Run two full charge-and-discharge cycles through normal splicer operation and the indicator will settle to a stable, accurate readout.

The replacement BTR-10 pack won't take a charge after sitting in my kit bag all winter. The charger light just blinks and stops.

Extended storage at low charge causes the cells to drop below the BMS recovery threshold — typically under 10V — and the charger's standard charge circuit won't engage below that floor. Plug the pack into the OEM charger and leave it connected for 45–60 minutes without interrupting the connection; most Fujikura chargers apply a trickle pre-charge pulse in this state before switching to normal charge mode. If the charger light transitions from blinking to solid after that window, the BMS has recovered — let it complete a full charge before use.

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