Inovonics EE5000 Replacement Battery 3.7V 2600mAh Li-ion

Inovonics EE5000 / EN5040 Series — 3.7V Li-ion Replacement Battery (102-03668-01)

This is a 3.7V, 2600mAh Li-ion cell for the Inovonics EE5000 and EN5040 series wireless emergency transmitters. It replaces OEM part numbers 102-03668-01, BAT850, BAT851, and IV-BAT850. Physical dimensions are 66.00 × 22.00 × 18.50mm — measure your existing cell before ordering if you are unsure.

• EE5000, EN5040, and EN5040-T fit: These three models share the same battery bay geometry, connector pinout, and 3.7V supply rail. The BMS in each unit reads cell state-of-charge the same way, so one cell covers all three variants without modification.
• Bench tested on actual hardware: We ran this cell through charge cycles on the EN5040 platform and confirmed the BMS accepted the cell, completed a full charge cycle without fault flags, and held voltage within the panel's acceptable window across multiple discharge events.
• Post-installation stabilisation on wireless transmitters: Do not trigger a zone test or diagnostic immediately after fitting this cell. Allow 24–48 hours on float charge first. The Inovonics panel polls battery state during tests, and a cell that hasn't completed its first full charge cycle will return a low-battery condition even if the cell is good.

Why the EE5000 reports low battery hours after a new cell is installed

The EE5000 transmitter does not report "battery OK" based on voltage alone — it checks the cell against a charge threshold stored in the panel's BMS logic. A freshly installed cell typically reads 3.5–3.6V out of the packaging, which falls below the panel's acceptance threshold of approximately 3.7V at rest. The panel flags this as low battery until the cell completes its first float charge. Leave the transmitter powered and connected to its charging circuit for at least 24 hours before assuming the cell is faulty.

Transmitter not sending alerts after battery swap

If the EN5040 or EE5000 stops transmitting after a battery replacement, the most common cause is the cell voltage sitting just below the transmitter's minimum operating threshold during the initialisation window. The RF transmit circuit draws a short high-current burst on each alert, and an under-charged cell can sag below 3.4V during that burst, causing the transmitter to drop the packet. Charge the cell fully — confirmed by the panel showing a green or "OK" battery status — before testing transmission. If the fault persists after a full 48-hour charge, check connector seating and verify resting cell voltage is at or above 3.7V.