BLU Vivo 4 IV Replacement Battery 3.8V 2300mAh

BLU Vivo 4 IV (D970L) — 3.8V Li-Polymer Replacement Battery

This is a 3.8V, 2300mAh Li-Polymer replacement battery for the BLU Vivo 4 IV (D970L) smartphone. It slots into the original battery bay and connects to the same charge IC and fuel gauge circuit. Capacity is rated at 8.74Wh — identical to the factory specification.

• Vivo 4 IV / D970L fit: Both model numbers share the same PCB layout, battery connector pinout, and BMS handshake protocol. One cell covers both variants without hardware modification.
• Bench tested on actual hardware: We ran charge and discharge cycles through a D970L unit, confirmed BMS communication at full charge acceptance, and verified the cell holds voltage above 3.6V under sustained screen and modem load.
• Fuel gauge recalibration on first use: On the first use after installation, run one complete discharge down to automatic shutdown before recharging. This gives the coulomb counter a full reference cycle against the new cell's actual discharge curve — without it, the percentage readout will drift.

Sudden shutdown at 20–30% on the replacement cell

This happens when the phone's fuel gauge IC is still calibrated to the old, degraded cell. The old cell had a steep voltage drop near depletion, so the IC learned to trigger shutdown earlier than the true empty point. A fresh cell has a flatter discharge curve, but the IC fires the cutoff at the same learned voltage threshold — which now occurs while real capacity remains. One full discharge-to-shutdown cycle resets that threshold against the new cell's actual curve. After that cycle, shutdowns at 20–30% stop.

Phone warm near the battery during the first two charges

A new Li-Polymer cell arrives with higher internal impedance than a conditioned cell. The charge IC pushes current into that higher impedance, which generates more heat than normal until the cell completes a few formation cycles. This is not a fault — it resolves after two to three full charge cycles as impedance drops. If the device stays hot beyond cycle three, check that the back cover is seated properly and not restricting heat dissipation from the charge IC.