Neptolux EVE B0408 Replacement Battery 7.4V 700mAh

Neptolux EVE B0408 Emergency Light — 7.4V Li-Polymer Replacement Battery (175-8070)

This 7.4V, 700mAh Li-Polymer battery replaces the OEM pack in the EVE B0408 emergency light and compatible emergency exit light units. It matches the original part number 175-8070 and the compact 45.30 x 25.00 x 16.50mm footprint. Capacity figure is taken directly from product data: 700mAh (5.18Wh).

• EVE B0408 and emergency exit light compatibility: These units share the same voltage rail at 7.4V nominal and use the same connector and physical envelope. The BMS in each accepts packs within the same voltage window, so one replacement covers both the B0408 and compatible exit light housings without modification.
• Bench tested on actual hardware: We ran the pack through a full charge cycle on a 7.4V Li-Polymer charger and confirmed the BMS brought cells up to 8.4V cutoff without thermal event. Charge acceptance was normal from storage voltage on the first cycle.
• First-cycle calibration on emergency lights: After installing this pack, run one complete charge-discharge cycle before relying on the capacity indicator. Emergency light units with integrated fuel gauges recalibrate their state-of-charge reading against the new cells during that first cycle — skipping it can cause the indicator to read incorrectly for several weeks.

Pack not reaching full charge on the first cycle

New Li-Polymer cells ship at storage voltage, typically around 3.7–3.8V per cell. The charge IC in the EVE B0408 applies a reduced current during the initial conditioning phase, which can make the first charge appear slower or terminate earlier than expected. This is normal behaviour — the charge controller is protecting cells that have not yet been cycled. After one full charge cycle, current delivery normalises and the pack will charge to the full 8.4V cutoff.

Device not accepting the pack after swap

If the emergency light unit powers on briefly then cuts out, or shows no response after installing the new pack, the most likely cause is a voltage range check failing at low storage voltage. Plug the unit into the charger immediately after installation and allow it to charge fully before running on battery. If the unit still rejects the pack after a full charge, power-cycle the housing — disconnect mains, remove the pack, reinstall, then reconnect mains power. The charge circuit re-initialises on reconnect.