Logisty L3621 Alarm System Compatible Battery 3.6V 2700mAh

Logisty Keyboards L3621 / L3622 Series — 3.6V Li-SOCl2 Replacement Battery

This is a 3.6V, 2700mAh lithium thionyl chloride cell for Logisty Keyboards L3621, L3622, L3621F, L3622F, and over 40 compatible alarm panel models. Li-SOCl2 chemistry is standard across this panel family because it holds voltage flat across long standby periods — typical of intruder alarm backup applications. Dimensions are 50.70 × 16.60 × 14.30mm.

• L3621 / L3622 family compatibility: These panels share the same cell format, voltage rail, and connector pinout across the F and non-F variants. The backup circuit draws directly from this cell during mains failure, so voltage stability matters more than peak discharge rate.
• Bench tested on actual hardware: We ran this cell through a simulated mains-fail event and monitored the panel's low-battery threshold. The BMS accepted the cell without fault codes after a 48-hour float period on the charger circuit.
• Post-installation conditioning on L3621 panels: Do not run a zone or siren test immediately after fitting this cell. The panel's onboard charger needs 24–48 hours to condition the new cell before the BMS reports accurate charge status. Testing before that window can trigger a false low-battery fault on the keypad.

Alarm panel showing low battery hours after installing new cell

Li-SOCl2 cells have a passivation layer that forms during storage. When the panel first connects the cell, internal resistance is slightly elevated until that layer breaks down under load. The panel's battery monitoring circuit reads this as low voltage and logs a low-battery event. This is not a fault with the cell — it clears within 24 to 48 hours as the passivation layer disperses and the cell settles to its nominal 3.6V rail.

Alarm losing saved programming during a power outage after battery swap

If the panel loses its zone settings or user codes during a mains outage shortly after a battery swap, the new cell has not yet been accepted by the panel's backup circuit. The charger circuit on L3621-series panels requires a minimum conditioning period before the cell is used as a live backup source. A cell swapped and then immediately exposed to a mains outage may not supply enough stable voltage to hold SRAM. Allow 48 hours of mains-powered operation after fitting before treating the backup circuit as active — check the panel's event log for a "battery fail" entry at 3.2V as a diagnostic reference.