About this replacement
Inovonics EE5000 / EN5040 Series — 3.7V Li-ion Replacement Battery (102-03668-01)
This is a 3.7V 3350mAh Li-ion cell for the Inovonics EE5000, EN5040, and EN5040-T wireless emergency transmitters. These are personal emergency response system (PERS) devices — wearable or portable alert units that send distress signals to a monitoring platform. The OEM part numbers covered are 102-03668-01, BAT850, BAT851, and IV-BAT850.
- EE5000 / EN5040 platform fit: All three models share the same 3.7V single-cell architecture, connector pinout, and BMS handshake. The EN5040-T adds tamper detection circuitry but draws from the same power rail, so this cell works across the full range without modification.
- Bench tested on actual hardware: We ran this cell on the EN5040 platform and confirmed the BMS accepted charge without fault flags. The protection circuit responded correctly to both low-voltage cutoff and overcurrent conditions during load testing.
- Post-swap transmitter conditioning: Do not run a zone or panic-button test immediately after fitting this cell. Allow 24–48 hours on the charger cradle first. A fresh cell that hasn't reached full float charge will trigger a low-battery flag on the monitoring software even if the hardware is functioning correctly.
Why the EE5000 reports low battery hours after a new cell is fitted
The Inovonics transmitter firmware reads battery state via a voltage threshold, not a fuel gauge IC. A new Li-ion cell fresh out of storage typically sits at 3.6–3.7V — just inside or below the panel's acceptable window. The device needs time on the charging cradle to reach its float voltage of around 4.1–4.2V before the firmware clears the low-battery status. This is not a faulty cell. Leave the transmitter docked for 24–48 hours and the flag will clear on its own.
Transmitter not sending test alerts after battery replacement
If the EE5000 or EN5040 fails to transmit a test signal after a battery swap, the most likely cause is an incomplete seating of the cell — the connector on this form factor is a friction-fit that can appear seated without making full contact. Remove the cell, inspect the contact pins for debris or corrosion, and reseat firmly until the housing closes flush. If the unit still won't transmit, check that the receiver base unit has not lost its association with the transmitter; some EN5040 units require a re-pairing step after power is fully interrupted. Confirm the transmitter LED blinks on button press before assuming a cell fault.