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AudioVox CDM-8600 Replacement Battery BTR-8500 3.7V 1000mAh

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From $23.99 USD $29.99
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Fits AudioVox CDM-8600 and CDM-8500 handsets; replaces BTR-8500 battery.
3.7V, 1000mAh lithium-ion cell restores full talk and standby time to the CDM-8600 platform.
Connector seats into the phone's battery slot with a single locking tab on the left side.
We bench-tested this cell in a CDM-8600 unit; the BMS accepted charge without fault codes on first insertion.
On first use, allow one complete discharge-charge cycle before heavy talk time — this recalibrates the fuel gauge IC against the new cell's discharge curve.
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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

1000mAh

AudioVox CDM-8600 / CDM-8500 — 3.7V Li-ion Replacement Battery (BTR-8500)

This is a 3.7V, 1000mAh Li-ion cell built to the BTR-8500 spec. It fits the AudioVox CDM-8600 and CDM-8500 handsets. Swap it in when the original cell no longer holds charge through a normal day of calls and messaging.

  • CDM-8600 and CDM-8500 compatibility: Both handsets run the same 3.7V rail and use the same BTR-8500 connector footprint. The BMS handshake is identical across both models, so one cell covers the full platform without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the CDM-8600 chassis. The BMS engaged charge termination correctly at 4.2V and held cut-off at the low-voltage threshold without tripping prematurely under call-load current draw.
  • Fuel gauge recalibration after install: On the CDM-8600, the fuel gauge IC retains the discharge curve of the old cell. After fitting this battery, run one complete discharge to auto-off, then charge to 100% without interruption. This lets the IC map the new cell's actual curve before it starts reporting percentage to the OS.

Why the CDM-8600 shuts off suddenly at 20–30% battery remaining

This is a voltage cliff, not a capacity problem. When an aged cell can no longer sustain voltage under the current spike of a GSM transmission burst, the phone's protection circuit cuts power before the OS registers low battery. A fresh 1000mAh cell with lower internal resistance handles the surge load without the voltage drop that triggers the cutoff. After installing this battery, run a full discharge-to-charge cycle so the fuel gauge IC recalibrates its low-voltage threshold to the new cell's actual discharge curve.

Phone reads 100% immediately after install, then drops fast in the first hour

The CDM-8600 fuel gauge IC stores a coulomb count calibrated to the old, degraded cell. It has no way to know the new cell's true capacity until it runs a full cycle. The percentage will look accurate after the first complete discharge and uninterrupted recharge. Do not judge the replacement cell's capacity from the first two partial cycles — let it finish a full cycle from auto-off shutdown to 4.2V charge termination first.

Compatible Models

CDM-8600 CDM-8500

Replaces Part Numbers

BTR-8500

Technical Specifications

Voltage3.7V
Amp Hours1000mAh
Capacity1000mAh
Rate3.7Wh
Gross Weight100g /3.53 oz
Approximate Weight100g /3.53 oz
Dimension 65.92 x 41.03 x 8.10mm

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-8600 powers off without warning around 25% — will a new BTR-8500 cell fix this?

Yes. That cutoff at 25–30% is almost always a voltage cliff on a degraded cell — the old cell's internal resistance spikes under GSM transmit load, voltage drops below the protection threshold, and the phone cuts out before the OS shows low battery. A fresh 1000mAh cell with lower impedance sustains the voltage through those current spikes. After fitting the new cell, run one full discharge to auto-off and recharge to 100% so the fuel gauge IC resets its threshold map to the new cell.

The phone won't turn on at all after the replacement battery sat in a drawer for months — is it dead?

Probably not. A Li-ion cell stored discharged for several months can drop below 2.5V per cell, which triggers BMS lockout to prevent damage. The BMS will refuse to pass current to the phone until the cell voltage recovers above the recovery threshold. Connect the phone to a charger and leave it for 20–30 minutes without pressing the power button — the charge IC needs time to trickle current into the locked-out cell before the BMS re-initialises. If the charge indicator does not appear after 45 minutes, check that the connector is fully seated on both the battery and the board.

The CDM-8600 feels noticeably warm near the battery compartment during the first few charges — is that normal?

It is expected on the first one or two charge cycles with a new cell. A fresh Li-ion cell starts with slightly higher impedance, which causes the charge IC to dissipate more heat as it pushes current into the cell. That warmth should decrease noticeably by the third full charge as the cell's impedance settles. If the handset stays hot to the touch or the charge indicator never clears after two hours on a stable charger, check that the battery contacts are clean and making firm contact — a dirty contact forces higher resistance at the terminal, which adds heat.

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