AKG N700NC Replacement Battery 3.7V 700mAh GSP902540

AKG N700NC — 3.7V Li-Polymer Replacement Battery (GSP902540)

This 3.7V, 700mAh Li-Polymer cell replaces the original GSP902540 battery in the AKG N700NC wireless noise-cancelling headphones. It powers the active noise cancellation circuit, Bluetooth radio, and audio playback simultaneously. Capacity is 700mAh (2.59Wh), matching the original specification.

• N700NC battery platform: The N700NC runs three concurrent loads — ANC processor, Bluetooth radio, and driver amplification — off a single 3.7V cell. The GSP902540 footprint and connector are specific to this housing; no other AKG cell fits without physical modification.
• Bench tested on actual hardware: We ran this cell under combined ANC-plus-Bluetooth draw and monitored BMS cutoff thresholds. The protection circuit held stable at both ends — no premature low-voltage cutoff under sustained load, no overcharge flag during a full top-up cycle.
• First-cycle charge protocol on the N700NC: Place the headset on charge immediately after fitting the new cell and let it complete a full cycle without interruption. The N700NC's onboard fuel gauge needs one uninterrupted charge to calibrate the state-of-charge reading accurately — cutting it short will cause the battery indicator to misreport level.

Why the N700NC cuts out mid-track with a new battery installed

The N700NC pulls peak current when ANC and Bluetooth are both active — the combined draw can momentarily dip cell voltage below the BMS low-voltage threshold even when the cell is not depleted. A new cell at storage voltage (typically 3.6–3.7V) has higher internal resistance than a conditioned cell, making it more prone to this voltage sag. After two to three full charge-discharge cycles, internal resistance drops and the sag under peak load stabilises. If cutouts persist past five cycles, check that the connector is fully seated — a partial connection increases contact resistance and amplifies the sag.

Battery indicator shows full charge but headset shuts off after short use

This happens when the fuel gauge is reading a stale calibration from the previous cell rather than the actual charge state of the new one. The N700NC stores the last known state-of-charge in firmware and applies it to whatever cell is fitted. A single full charge cycle — from the point the replacement cell is fitted, without interruption — forces the gauge to reset against the new cell's real capacity. After that cycle completes, the indicator will reflect actual charge level. Confirm the cycle is complete when the charging LED extinguishes and voltage holds at 4.18–4.20V.