AudioVox Shuttle BTR7B Compatible Battery 3.7V 650mAh

AudioVox Shuttle / CDM-8964 — 3.7V Li-ion Replacement Battery (BTR7B)

This is a 3.7V 650mAh lithium-ion cell replacing part number BTR7B in the AudioVox Shuttle and CDM-8964 mobile phones. It slots into the original battery bay and connects via the factory contact plate. Voltage and physical dimensions match the OEM spec exactly — 53.50 × 53.00 × 4.00mm.

• Shuttle and CDM-8964 compatibility: Both models use the same BTR7B footprint, contact layout, and 3.7V nominal rail. The BMS handshake is identical across this pair, so one cell works in either device without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the CDM-8964 platform. The onboard charge IC accepted the cell without fault flags, and the BMS held the low-voltage cutoff at the expected threshold without tripping prematurely.
• Fuel gauge recalibration after swap: On first use after installing this cell, run one full discharge down to automatic shutdown, then charge uninterrupted to 100% without interrupting the cycle. This gives the fuel gauge IC a complete reference curve for the new cell before daily use begins.

Why the Shuttle reports wrong battery percentage after a cell swap

The Shuttle's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The IC reads the new cell's voltage against old reference points and reports a percentage that can be several points off — often too high early in discharge and too low near the end. One full uninterrupted discharge-charge cycle rewrites the reference and corrects the readout.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display draws a short burst of current and the cell voltage drops below the BMS low-voltage cutoff faster than the fuel gauge tracks it. The OS never registers zero percent — it simply cuts off. On a new cell this usually means the fuel gauge IC has not yet completed a calibration cycle and is misreporting usable capacity. Run one full discharge-charge cycle, then confirm the shutdown threshold moves closer to 5–10%. If the phone still cuts out above 20% after two full cycles, check that the contact pins on the battery bay are seating cleanly against the cell terminals.