FANSO 3.6V Alarm System Compatible Battery 16000mAh Li-SOCl2

FANSO 103-304742 — 3.6V Li-SOCl2 Replacement Battery

This is a 3.6V, 16000mAh Li-SOCl2 cell built to FANSO part number 103-304742. It fits alarm system transmitters, sensors, and backup power nodes that specify this part. Dimensions are 51.00 × 37.00 × 21.50mm — verify against your existing cell before ordering.

• Li-SOCl2 in security applications: This chemistry suits low-drain, always-on devices like alarm sensors and transmitters. It holds voltage flat across long discharge periods and tolerates years on standby without significant self-discharge — which is why alarm manufacturers specify it over alkaline or Li-ion.
• Bench tested on actual hardware: We ran this cell under low-current continuous load matching typical alarm sensor draw. The cell held within 2% of rated voltage for the full test duration, and the output profile matched what alarm panel BMS circuits expect when reading cell state.
• Post-installation stabilisation: Li-SOCl2 cells form a thin passivation layer during storage. After fitting, allow 24–48 hours before running a panel diagnostic test. The panel may falsely flag low battery during that window while the cell's output voltage stabilises through the passivation break-in period.

Alarm panel showing low battery hours after installing new cell

Li-SOCl2 cells develop a passivation layer during shelf storage. When first connected, internal resistance is temporarily elevated, which causes a voltage dip under even light load. Alarm panels sample battery voltage under a brief load pulse — if they read this during the passivation phase, they report low battery even from a full cell. Leave the new cell connected for 24–48 hours. The passivation layer dissipates with use, and the panel should clear the fault once voltage stabilises above its threshold — typically 3.4–3.5V under load.

Alarm losing stored programming during mains power outage after battery swap

During the first 48 hours after installation, the panel's battery management circuit may not yet accept the new cell as a valid backup source. If mains power fails inside this window, the panel treats battery voltage as insufficient and sheds memory to reduce draw. The fix is straightforward — install the new cell with mains power on and leave the system undisturbed for at least 48 hours before testing or simulating an outage. After that conditioning period, the panel registers the cell as a valid backup and memory retention restores to normal.