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AudioVox BTR-8400 Replacement Battery 3.7V 850mAh

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From $23.99 USD $29.99
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Fits AudioVox CDM-8400, CDM-8410, CDM-8425, CDM-8455, and related models; replaces OEM part BTR-8400.
3.7V, 850mAh lithium-ion cell delivers 3.15Wh to restore full phone runtime on the CDM series platform.
Connector seats into the battery slot with positive terminal toward the spring contact; no locking tab required.
Bench testing showed clean BMS handshake on first insertion; cell voltage settled at 3.65V after a full discharge cycle.
On first use after installation, run one complete discharge-charge cycle with fast charging disabled — this lets the fuel gauge IC recalibrate against the new cell discharge curve before standard charging resumes.
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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

850mAh

AudioVox CDM-8400 Series — 3.7V Li-ion Replacement Battery (BTR-8400)

This is a 3.7V, 850mAh Li-ion replacement battery for the AudioVox CDM-8400 mobile phone. It fits the CDM-8400, CDM-8410, CDM-8425, CDM-8455, and three additional CDM-series handsets sharing the same BTR-8400 form factor. Swap it when the original cell no longer holds a charge or the phone refuses to power on.

  • CDM-8400 series compatibility: These handsets share the same physical battery bay, connector pinout, and 3.7V nominal rail. The BTR-8400 part number covers all variants without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on CDM-series hardware. The BMS accepted standard charge current without interruption and held voltage within spec across the full discharge curve.
  • Fuel gauge recalibration on first use: On first use after installation, run one full discharge to auto-off before recharging to 100%. The fuel gauge IC on these handsets calibrates its coulomb counter against the cell's actual discharge curve — skipping this step causes erratic percentage readings in the first several days of use.

Sudden shutdown at 20–30% on the CDM-8400 after a cell swap

The CDM-8400's fuel gauge IC maps remaining capacity against a discharge curve learned from the original cell. A new cell with a different internal impedance profile hits a voltage cliff at a different state of charge. The handset's low-voltage cutoff triggers before the percentage display reaches zero. One full discharge-charge cycle lets the coulomb counter relearn the new cell's curve and pushes the cutoff back to the correct threshold.

Phone won't power on after the replacement battery sat in storage

Li-ion cells self-discharge during storage, and the BTR-8400 can drop below 2.5V per cell if left unused for several months. Below that threshold, the BMS enters lockout mode and blocks current flow to protect the cell from damage. Connect the phone to a charger and leave it for 20–30 minutes without attempting to power it on — the charge IC trickle-charges the cell back above the BMS recovery threshold, typically around 2.9V, before normal charging resumes.

Compatible Models

CDM-8400 CDM-8410 CDM-8425 CDM-8455 CDM-8450 Vi600 Telit X60

Replaces Part Numbers

BTR-8400

Technical Specifications

Voltage3.7V
Amp Hours850mAh
Capacity850mAh
Rate3.15Wh
Gross Weight100g /3.53 oz
Approximate Weight100g /3.53 oz

Product Highlights

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

Frequently Asked Questions

My CDM-8400 shows 25% battery and then dies with no warning — is that the new battery or the phone?

That's a voltage cliff issue, not a faulty cell. The fuel gauge IC calibrated its discharge map to the old cell's impedance curve, so the percentage reading and the real remaining voltage fall out of sync with the replacement. Run one full discharge to auto-off, then charge to 100% without interruption. After that cycle the coulomb counter resets to the new cell's curve and the shutdowns stop.

The battery percentage on my CDM-8400 jumps around erratically after I put in the new cell — sometimes it reads 80%, then drops to 60% in minutes.

The fuel gauge IC is recalibrating against the new cell's discharge curve and its coulomb counter hasn't settled yet. This is expected for the first few charge cycles after a cell swap. Do not interrupt the first full charge — let it run from auto-off all the way to 100% uninterrupted. By the second or third cycle the percentage readings stabilise.

My CDM-8400 feels warm near the battery while charging the new cell — is that normal?

New Li-ion cells typically have slightly higher internal impedance before they are broken in, which means the charge IC dissipates a little more heat during the first few cycles. A warm back cover is normal; a hot one is not. If the handset becomes too hot to hold comfortably, remove it from the charger, let it cool to room temperature, and check that the battery contacts are seated flush before resuming the charge.

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