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microTALK LI3900-2 DX Compatible Battery 7.4V 700mAh BK-71216

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From $27.99 USD $34.99
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Fits microTALK LI3900-2 DX and LI6500-2 WX models, replaces OEM battery BK-71216.
7.4V 700mAh lithium-ion cell delivers stable voltage for 14-mile to 20-mile two-way radio transmission.
Battery uses standard radio connector with positive-first orientation and no locking tab on this platform.
We bench-tested the BMS under sustained PTT load — no overcurrent cutoff, voltage sag within spec.
If the charger dock blinks red on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly for BMS handshake acceptance.
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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

7.4V

Amp

700mAh

microTALK LI3900-2 DX Series — 7.4V Li-ion Replacement Battery (BK-71216)

This 7.4V 700mAh Li-ion pack replaces the BK-71216 battery across microTALK consumer two-way radios. It fits the LI3900-2 DX, LI5600-2 DX, LI6000-2 WX, LI6500-2 WX, and four additional models in the same family. Voltage, connector, and BMS communication match the OEM specification.

  • LI-series model compatibility: The LI3900-2, LI5600-2, LI6000-2, and LI6500-2 all share the same 7.4V battery bay, contact layout, and BMS handshake protocol — that is why one pack number covers the entire range.
  • Bench tested on actual hardware: We cycled this pack through PTT transmit loads on the LI-series platform. The BMS held steady through repeated transmit current spikes without tripping into protection mode, and the charger dock accepted the pack without fault on first insertion.
  • First insertion on the dock: If the charger LED does not respond immediately, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The LI-series dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the LI3900-2 cuts out mid-transmission on a new BK-71216

A freshly shipped Li-ion cell sits at storage voltage — typically 3.6–3.7V per cell, not the 4.2V per cell full-charge level. When you press PTT, transmit current spikes sharply. If the pack voltage is already low, that spike can push the BMS into overcurrent protection and drop the connection. The radio is not faulty — the cell just needs a full charge cycle before it can sustain transmit loads. Charge completely before the first use in any RF application.

Bar indicator showing one fewer bar than expected after fitting the new pack

The LI-series radios use a simple voltage-threshold system to display battery bars — each bar corresponds to a voltage window, not a measured capacity. A new cell at storage voltage will read one bar low until it reaches its first full charge. This is not a faulty pack or a mismatch. Charge the pack fully in the dock and the indicator will move to the correct level, typically at or above 8.2V resting.

Compatible Models

LI3900-2 DX 14-Mile Radio LI6500-2 WX 20-Mile Radio with weather LI5600-2 DX 20-Mile radio LI6000-2 WX 17-Mile Radio with weather LI4900-2 WX 18-Mile Radio with weather LI6700-2 WX22-Mile Radio with weather CXR800 27-Mile Radio with weather CXR700 25-Mile Radio

Replaces Part Numbers

BK-71216

Technical Specifications

Voltage7.4V
Amp Hours700mAh
Capacity700mAh
Rate5.18Wh
Net Weight43g /1.52 oz
Gross Weight68g /2.40 oz
Approximate Weight68g /2.40 oz
Dimension 50.00 x 36.20 x 12.80mm

Product Highlights

  • Brand: microTALK
  • 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 LI3900-2 transmits for a second then cuts out — could the new BK-71216 be faulty?

Almost certainly not faulty. A freshly shipped Li-ion cell ships at storage voltage, and the PTT transmit spike at that voltage level is enough to trip the BMS into overcurrent protection. Charge the pack fully before the first transmit session. If cut-outs continue after a full charge, check that the gold contacts on both the pack and the radio are clean and making firm contact.

The charger dock LED just blinks and never moves to a steady charge light after fitting the replacement battery — what's wrong?

A blinking fault LED on the LI-series dock usually means the pack voltage came in below the dock's acceptance threshold after extended storage. Remove the pack, wipe the gold contact strip with a dry cloth, and reseat it firmly to complete the BMS handshake. If the dock still rejects it, try a short warm-up charge using a compatible USB Li-ion charger at the correct 7.4V rating to bring the cell above 7.0V, then return it to the dock.

The radio drops to noticeably weaker audio and reduced TX range partway through use — is this a capacity issue with the 700mAh rating?

This is voltage sag, not a capacity defect. Under sustained RF output, cell voltage drops temporarily, and the radio's transmit power scales back as a result. The 700mAh rating matches OEM spec for this platform, so swapping to this pack does not reduce available power versus the original. If sag happens early in a charge cycle, check that the pack reached a full charge — resting voltage should read 8.2–8.4V before use.

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