About this replacement
Xiaomi Redmi 2 / 2A — 3.8V Li-ion Replacement Battery (BM44)
This is a 3.8V, 1500mAh Li-ion replacement battery for the Xiaomi Redmi 2 and Redmi 2A smartphones. It replaces OEM part number BM44 and fits the standard battery bay on both models. Swap this in when the original cell no longer holds a charge or causes unexpected shutdowns.
- Redmi 2 and Redmi 2A fit: Both models share the same chassis size, connector pinout, and BMS handshake protocol — one cell covers both. The BM44 form factor is identical across the two variants at 64.60 × 55.60 × 5.00mm.
- Bench tested on actual hardware: We ran this cell through a full discharge-charge cycle on a Redmi 2 unit. The BMS accepted charge at standard rate, cell voltage stabilised at 4.35V at full capacity, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before the OS reports accurate percentage readings.
Sudden shutdown at 20–30% on the Redmi 2 after a cell swap
This is a voltage cliff issue, not a faulty battery. The Redmi 2's fuel gauge IC was calibrated to the old, degraded cell's discharge curve. When the phone reports 20–30%, the new cell's actual voltage may still be well above cutoff, but the IC triggers a shutdown because it expects the old cell's steeper voltage drop at that percentage. One full discharge down to automatic shutoff — then a full charge — forces the coulomb counter to recalibrate against the new cell. After that cycle, shutdowns at high percentages stop.
Phone feels warm near the battery on the first charge after replacement
A new cell has higher internal impedance than a broken-in one. On the first charge cycle, the Redmi 2's charge IC pushes current into that higher-impedance cell, which generates slightly more heat than normal. This is expected and reduces after the first two to three cycles as impedance settles. If the phone feels hot rather than warm, or heat continues past the third cycle, check that the battery connector is fully seated — a partial connection forces the charge IC to work harder. Recheck the connector and confirm voltage reads 3.8V at rest before charging again.