Nokia E90 Communicator Replacement Battery 3.7V 1500mAh

Nokia E90 Communicator Series — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1500mAh Li-ion battery for the Nokia E90 Communicator and related Eseries smartphones including the E61i, E71, and E90i. It fits the shared battery bay across these models, which use the same cell format and connector. Install it when the original cell can no longer hold charge through a full working day.

• Eseries shared cell platform: The E90, E61i, E71, and E90i all draw from the same 3.7V Li-ion cell format with identical contact placement and BMS handshake protocol — that is why one replacement covers all of them without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on an E90 unit. The BMS accepted the charge sequence without error flags, and the protection circuit tripped correctly at the low-voltage threshold during deep-discharge testing.
• Fuel gauge recalibration on first use: On first installation, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before normal use. The E90's fuel gauge IC is calibrated to the old cell's discharge curve — skipping this step leaves the percentage readout unreliable for several cycles.

Why the E90 reports wrong battery percentage after a cell swap

The E90 uses a coulomb-counting fuel gauge IC that builds its model of cell capacity over repeated cycles. When you swap the physical cell, the IC still references discharge curves logged against the old, degraded cell. The new cell has higher actual capacity, so the percentage readout collapses faster than reality in early cycles. One full uninterrupted discharge-charge cycle forces the IC to reset its reference baseline against the new cell's actual voltage profile.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under load — the WCDMA radio and screen backlight together can pull enough current to cause a voltage cliff before the percentage gauge reaches zero. The BMS triggers a hard cutoff when cell voltage falls below roughly 3.0V under that combined load, even if the reported percentage still looks safe. The fix is to complete the fuel gauge recalibration cycle described above — accurate calibration moves the software shutdown threshold to match the cell's real voltage floor. If shutdowns persist after two full cycles, check that the battery contacts in the bay are clean and making full contact.