UTStarcom CDM7076 Replacement Battery BTR1 3.7V 800mAh Li-ion

UTStarcom CDM7076 — 3.7V Li-ion Replacement Battery (BTR1)

This is a 3.7V, 800mAh Li-ion cell for the UTStarcom CDM7076 mobile phone. It replaces the original BTR1 when the existing cell no longer holds a charge or fails to power the handset through normal use. Dimensions are 54.52 × 35.08 × 4.90mm — verify against your original battery before fitting.

• CDM7076 platform fit: The CDM7076 runs a single-cell 3.7V rail. This BTR1 replacement matches that rail voltage and uses the same connector and contact layout as the factory cell, so the phone's charge IC sees no difference at the hardware level.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS held cutoff correctly at both ends — no overcharge trip, no undervoltage latch during deep discharge simulation.
• Fuel gauge recalibration on first install: On first use, disable any fast-charge mode and run one full discharge-to-charge cycle. This lets the phone's fuel gauge IC map the new cell's discharge curve before it starts reporting accurate percentages.

Sudden shutdown at 20–30% on the CDM7076 after a cell swap

The CDM7076's modem and screen draw current in short, sharp bursts. An aged or uncalibrated cell can't sustain voltage under that load, so it hits the BMS undervoltage threshold before the fuel gauge reaches zero. The phone shuts off even though the reported percentage looks fine. One complete discharge-charge cycle after fitting the new BTR1 lets the fuel gauge IC recalibrate its coulomb counter to the actual cell capacity, which closes the gap between reported and real charge state.

Phone won't power on after the BTR1 sat in storage

Li-ion cells self-discharge during storage. If the BTR1 dropped below roughly 2.5V per cell, the BMS enters a lockout state to prevent damage and the phone won't respond to the power button. Connect the phone to a wall charger — not a PC USB port — and leave it for 15–20 minutes without pressing anything. The charge IC will trickle current into the cell to bring it above the BMS recovery threshold. Once voltage climbs above 3.0V, the BMS unlocks and the phone will power on normally.