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EADS BLN-5i Replacement Battery THR9 3.7V 2300mAh

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From $42.99 USD $52.99
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Fits EADS THR9, THR9i, and THR9 C-30 radios; replaces OEM battery part numbers BLN-5i and BLN-6.
3.7V and 2300mAh capacity matches the original pack voltage and discharge curve for this portable radio platform.
Battery uses a standard connector block that seats vertically into the radio's lower chassis slot with a mechanical locking tab.
We bench-tested this cell in a THR9 charger dock; the BMS accepted the handshake on first insertion and delivered full charge in one cycle.
If the charger dock shows a fault LED after inserting this cell, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly — the THR9 platform requires a clean contact cycle to accept the new BMS handshake before charging begins.
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

3.7V

Amp

2300mAh

EADS THR9 Series — 3.7V Li-ion Replacement Battery (BLN-5i / BLN-6)

This is a 3.7V, 2300mAh Li-ion battery pack for the EADS THR9, THR9i, and THR9 C-30 portable two-way radios. It replaces OEM part numbers BLN-5i and BLN-6. Dimensions are 97.46 × 53.62 × 14.96mm — same physical envelope as the original pack.

  • THR9 / THR9i / THR9 C-30 fit: All three variants run the same 3.7V single-cell architecture with the same connector and BMS handshake protocol. One pack covers the full lineup without adapter or modification.
  • Bench tested on actual hardware: We cycled this pack through full charge and load discharge on the THR9 platform. The BMS engaged overcurrent protection correctly at transmit-draw peaks and released cleanly on PTT release without latching lockout.
  • First-insertion contact check: If the charger dock shows a fault LED on first seating, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The THR9 dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the THR9 cuts out mid-transmission on a freshly inserted battery

New cells ship at storage voltage — typically 3.6–3.7V — not at full charge. When you key up, transmit current spikes sharply and can pull the resting cell voltage below the BMS overcurrent threshold for a fraction of a second. The BMS trips, the radio drops off air, and it recovers only when PTT is released. One full charge cycle before operational use brings cell voltage up to 4.1–4.2V and gives the BMS the headroom it needs to handle transmit spikes without tripping.

THR9 bar indicator showing one fewer bar than expected on a new pack

The THR9 uses a simple voltage-threshold bar indicator — each bar corresponds to a fixed voltage band. A new pack at storage voltage sits in a lower band and displays one fewer bar than a fully charged cell. This is not a capacity fault. Charge the pack fully in the dock until the LED goes green, then reinsert. The indicator will move to the correct bar at or above 4.1V.

Compatible Models

THR9 THR9i THR9 C-30

Replaces Part Numbers

BLN-5i BLN-6

Technical Specifications

Voltage3.7V
Amp Hours2300mAh
Capacity2300mAh
Rate8.51Wh
Net Weight67g /2.36 oz
Gross Weight117g /4.13 oz
Approximate Weight117g /4.13 oz
Dimension 97.46 x 53.62 x 14.96mm

Product Highlights

  • Brand: EADS
  • 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 THR9 drops off air every time I press PTT on a new battery — is the pack faulty?

This is a BMS overcurrent trip, not a defective pack. New cells ship at storage voltage, and the transmit current spike pulls the cell momentarily below the BMS protection threshold. The BMS cuts output, then resets when you release PTT. Charge the pack fully in the dock before first use — once the cell reaches 4.1–4.2V, the BMS has enough headroom to handle transmit draw without tripping.

The THR9 charger dock is blinking a fault LED and never starts charging — what's wrong?

The THR9 dock runs a contact-and-voltage handshake before it accepts a pack. If the cell voltage is below the dock's acceptance floor (typically around 3.0V after extended storage), the dock rejects the pack and blinks fault. Remove the battery, wipe the gold contacts with a dry cloth, reseat firmly, and hold it seated for three seconds. If the dock still won't accept it, the cell may have dropped below BMS recovery threshold — place the pack in a compatible Ni-MH/Li-ion recovery charger set to 3.7V Li-ion to bring the cell above 3.0V, then transfer it to the THR9 dock.

The THR9 transmit power feels noticeably weaker toward the end of a shift — is that voltage sag?

Yes. As the cell discharges toward its lower voltage cutoff, sustained RF output draws more current than the cell can cleanly supply at low state-of-charge, causing voltage to sag under load. The radio detects the sag and steps down TX power to stay within its operating envelope. This is normal cell behaviour, not a fault. If it happens early in a shift, the cell may have high internal impedance from age or shallow cycling — swap to a fresh pack and confirm the original reaches 4.1V on a full charge before relying on it operationally.

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