Nokia Asha 502 BL-5A Replacement Battery 3.7V 800mAh

Nokia Asha 502 — 3.7V Li-ion Replacement Battery (BL-5A)

This is a 3.7V, 800mAh Li-ion replacement battery for the Nokia Asha 502. It uses OEM part number BL-5A and fits directly into the Asha 502's battery bay. Capacity is rated at 2.96Wh, matching the original cell specification.

• Asha 502 fit: The BL-5A format is specific to the Asha 502 platform — the connector pinout, physical dimensions (46.10 × 39.80 × 5.20mm), and BMS voltage parameters match what the device's charge IC expects at 3.7V nominal.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Asha 502 platform. The BMS accepted the charge IC handshake without fault flags, and the cell held voltage through a full discharge cycle without mid-cycle dropout.
• Fuel gauge recalibration on first use: After installing this cell, run one full discharge down to auto-shutoff before recharging completely. The Asha 502's fuel gauge IC calibrates its coulomb counter against that first full cycle — skipping it causes the percentage readout to drift.

Sudden shutdown at 20–30% on the Asha 502 after a cell swap

A new Li-ion cell has a slightly different discharge curve than the aged cell the fuel gauge IC learned over time. When the Asha 502 reports 25% remaining, the actual cell voltage may already be near the cutoff threshold for the modem and display load. The BMS triggers a hard shutdown to protect the cell before the OS has time to warn you. One full discharge-to-shutoff cycle followed by a full charge resets the IC's reference curve and eliminates most of these early shutdowns.

Phone warm near the battery compartment on first charge

A new cell arrives with higher internal impedance than a conditioned one. The Asha 502's charge IC pushes current into that higher-impedance cell at the same rate it used with the old battery, which generates more heat during the first few charge cycles. This is expected behaviour and not a fault in the cell or the device. After two to three full charge cycles, internal impedance drops and the warmth resolves — check that the back cover seats flush so heat can dissipate normally.