Optus E589 Compatible Battery 3.7V 2600mAh Li-Polymer

Optus E589 — 3.7V Li-Polymer Replacement Battery

This 3.7V, 2600mAh lithium-polymer battery replaces the original cell in the Optus E589 portable WiFi hotspot. The E589 shares a mobile data connection with multiple devices over WiFi, drawing power from both the cellular modem and the wireless radio simultaneously. Capacity figures are taken directly from product specifications — 9.62Wh total energy.

• E589 fit confirmation: The E589 runs a combined cellular-plus-WiFi load on a single 3.7V cell. The physical footprint — 66.38 × 55.40 × 5.90mm — must match exactly, as the hotspot housing has no tolerance for dimensional variance and the connector is polarity-keyed.
• Bench tested on actual hardware: We cycled this cell under a simulated multi-device load — modem active, WiFi broadcasting — and monitored the BMS cutoff thresholds. The protection circuit tripped correctly at both the high-voltage charge ceiling and the low-voltage discharge floor without requiring a manual reset.
• Ventilation during active sessions: Keep the E589 flat on a hard surface with the vents unobstructed. When connected devices are at range limit, the cellular radio runs at full output power — that heat feeds directly into the battery cavity and accelerates cell wear faster than anything else in normal use.

Why the E589 disconnects connected devices mid-session under load

The E589 pulls power from two radio subsystems at once — the cellular modem and the 2.4GHz WiFi transmitter. When multiple devices are active and the cellular signal is weak, both radios ramp to maximum output simultaneously. That combined current spike can drag cell voltage below the BMS hold threshold momentarily, triggering a protective disconnect before the battery is depleted. A degraded original cell makes this worse; a fresh cell at full charge holds the voltage rail stable through those spikes.

E589 won't power on after sitting unused for several weeks

Lithium-polymer cells self-discharge slowly during storage. If the E589 sat unused long enough, the cell may have dropped below the minimum boot voltage — typically around 3.0V — and the BMS locks out to prevent damage. Plugging in the charger and leaving it for 30–45 minutes usually recovers the cell if it hasn't been stored fully depleted for months. If the charge LED never activates, the cell has reached 0V and will not recover — replace it and confirm the new cell reads at least 3.2V open-circuit before first boot.