iSpan DDV-965 Replacement Battery 3.7V 750mAh BTA002

iSpan DDV-965 — 3.7V Li-ion Replacement Battery (BTA002)

This is a 3.7V, 750mAh Li-ion cell that replaces the original BTA002 battery in the iSpan DDV-965 smartphone. It fits the DDV-965 directly, matching the original connector and BMS handshake. Capacity is 750mAh (2.78Wh) — taken from product data, not estimated.

• DDV-965 fitment: The DDV-965 uses a compact 3.7V single-cell architecture with a specific BMS handshake on the protection circuit. This cell matches that voltage rail and connector pinout, so the phone's charge IC recognises it without throwing a fault.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the DDV-965 platform. The BMS accepted the cell on first connection, charge termination triggered correctly at 4.2V, and the protection circuit tripped at the expected low-voltage cutoff.
• Fuel gauge recalibration on first use: On first installation, disable fast charging if the device supports it and run one full discharge-charge cycle at standard rate. This gives the fuel gauge IC time to map its coulomb counter against the new cell's actual discharge curve before high-current charging begins.

Why the DDV-965 reports the wrong battery percentage after a cell swap

The DDV-965 uses a fuel gauge IC that builds its state-of-charge model from the previous cell's discharge history. When a new cell goes in, the IC is still working from the old curve. Until it re-learns the new cell, it will report percentages that do not match actual charge level — often reading too high or dropping suddenly. One full discharge down to automatic shutdown, followed by a full charge to 100%, forces the IC to recalibrate its coulomb counter against the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the DDV-965

This happens when the cell voltage drops below the modem or display's minimum operating threshold before the fuel gauge reaches 0%. Under load — an active call, screen at full brightness, or background sync — the cell voltage collapses faster than the fuel gauge predicts. The phone's power rail drops below the processor's brown-out threshold and the device shuts off hard. If this occurs, let the phone cool for two minutes, then recharge to full. If it persists after one full recalibration cycle, check that the battery connector is fully seated — an intermittent contact increases internal resistance and accelerates voltage sag under load.