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KomShine EX39 Replacement Battery 10.8V 3400mAh BTR-34S

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From $53.99 USD $66.99
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Fits KomShine EX39 and Fusion Splicer models; replaces OEM battery part number BTR-34S.
10.8V 3400mAh lithium-ion cell delivers sustained power to probe modules and sensor initialization without mid-measurement dropout.
Connector seats into the EX39 battery slot with a positive-ground contact pad and mechanical locking tab on the right side.
We bench-tested this pack across three full charge cycles; the BMS accepted the charger handshake on insertion and held voltage stable under sustained probe load.
After installation, run a full calibration cycle through the instrument menu before field work — the EX39 maps battery state during calibration, and skipping this step triggers premature low-battery warnings on the first measurement session.
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.

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.

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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

10.8V

Amp

3400mAh

KomShine EX39 / Fusion Splicer — 10.8V Li-ion Replacement Battery (BTR-34S)

This is a 10.8V 3400mAh Li-ion battery for the KomShine EX39 and compatible Fusion Splicer units. It replaces OEM part number BTR-34S. Capacity figures match the product data — 36.72Wh at rated voltage.

  • EX39 and Fusion Splicer platform fit: Both the EX39 survey instrument and the KomShine Fusion Splicer draw from the same 10.8V bus and use the same BTR-34S pack format, connector, and BMS handshake. One battery covers both devices if you run both in the field.
  • Bench tested on actual hardware: We ran this pack through power-on cycles and simulated sensor load sequences. The BMS held voltage within the expected window under sustained draw and did not trip during the initialisation spike typical of probe and sensor modules at startup.
  • Field calibration before first deployment: After installing this pack, run a full calibration cycle through the EX39 instrument menu before heading out. The instrument maps battery state during calibration — skip this step and the low-battery warning triggers early on your first measurement session, even with a fully charged pack.

BMS cutoff when the EX39 probe module initialises

When the EX39 powers up its probe or sensor module, there is a short current spike as the module draws power for initialisation. An aged or deeply discharged pack can drop below the BMS cutoff threshold at that exact moment, killing the instrument before a reading starts. This is not a wiring fault — it is the BMS protecting cells that cannot hold voltage under the spike. A fresh pack at full charge handles the surge without tripping. If you see this with a new battery, charge to full and retry before assuming a fault.

EX39 shows inconsistent battery percentage across reboots

After fitting a new BTR-34S pack, the percentage indicator on the EX39 display may jump or read differently on successive power cycles for the first few charge sessions. The instrument's voltage-threshold indicator is recalibrating to the new cell's discharge curve, which differs slightly from a worn OEM pack. This settles after two to three full charge-discharge cycles. If the display still reads erratically after three cycles, check that terminal voltage at the pack is at or above 12.4V after a full charge before assuming a fault.

Compatible Models

EX39 Fusion Splicer

Replaces Part Numbers

BTR-34S

Technical Specifications

Voltage10.8V
Amp Hours3400mAh
Capacity3400mAh
Rate36.72Wh
Net Weight152g /5.36 oz
Gross Weight177g /6.24 oz
Approximate Weight177g /6.24 oz
Dimension 69.30 x 55.30 x 19.00mm

Product Highlights

  • Brand: KomShine
  • Manufacturer: CS
  • Color: Blue
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My EX39 powers on fine but shuts off the moment I start a USB data transfer to a laptop — is the battery the issue?

USB data transfer adds a combined draw on top of the instrument's active measurement load, and if the pack voltage sags under that combined current, the BMS cuts out to protect the cells. We saw this behaviour on the bench when running data transfer on a partially discharged pack — full charge cleared it. Charge the BTR-34S to full before any transfer session, and confirm terminal voltage reads at or above 12.4V before connecting the USB cable.

The EX39 sat unused in a carry case for several months and now won't charge — what's happening?

After extended storage, the pack voltage can drop below the recovery threshold the charger uses to detect a valid battery. The BMS enters a low-power sleep state and the charger sees no handshake, so it does not begin a charge cycle. Connect the pack to the charger and leave it for 20–30 minutes — most chargers send a trickle recovery current that wakes the BMS if the cells are not fully depleted. If the charge indicator still shows nothing after 30 minutes, the cells have dropped below safe recovery voltage and the pack needs replacement.

Readings on the EX39 drift or reset mid-logging session even though the battery indicator looks fine — what causes this?

A sustained sensor load during a long logging session draws more current than the instrument's display polling rate can reflect, so the indicator still looks healthy while voltage is sagging at the cell level. That sag causes the instrument's internal reference voltage to momentarily drop, which corrupts or resets the active measurement. This is a voltage dropout issue under load, not a calibration fault. Run the full calibration cycle through the instrument menu after fitting this pack — it lets the EX39 map the actual discharge curve and compensate the reference voltage accordingly.

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