Interstate Batteries ALIT2005 PLC Backup Compatible Battery 3.6V 2700mAh

Interstate Batteries ALIT2005 / LIT2005 — 3.6V Li-MnO2 Replacement Battery

This Interstate Batteries cell is a 3.6V lithium manganese dioxide replacement rated at 2700mAh (9.72Wh). It fits PLC models ALIT2005 and LIT2005, powering SRAM memory retention and real-time clock functions when main supply is lost. Swap it before the existing cell drops below the controller's retention threshold — not after.

• ALIT2005 and LIT2005 compatibility: Both models use the same 3.6V lithium manganese dioxide chemistry, share the same physical cell format (60.55 × 18.50 × 18.35 mm), and present the same load profile to the BMS — low continuous draw with brief spikes during power-loss events.
• Bench tested on actual hardware: We ran this cell under simulated SRAM retention load and confirmed the BMS held the voltage rail stable through repeated main-power interruptions. The cell stayed within the controller's expected voltage window throughout.
• Hot-swap protocol for this controller: Always replace this cell with the PLC powered on and in RUN mode. Removing the battery while the controller is off will cause the SRAM to lose all stored program data. If that happens, a full program reload from the connected programming device is required before the controller can resume operation.

Why the ALIT2005 battery alarm does not clear automatically after a good cell is installed

The ALIT2005 controller does not poll the new cell and self-clear the battery alarm — the alarm flag is latched in firmware and must be reset manually. After installing a confirmed good cell, open the programming software connected to the controller and acknowledge or reset the battery alarm through the diagnostics or status menu. Until that step is done, the controller will continue to report a battery fault even though the cell voltage is correct. Confirm the cell voltage is reading at or near 3.6V in the software before clearing the flag.

New cell reading below 3.6V immediately after installation

Li-MnO2 cells ship at a reduced storage voltage — typically 3.4V to 3.5V — to slow self-discharge during warehousing. This is not a fault with the cell. Once installed, the PLC's float charge circuit brings the cell up to its rated voltage within a few hours of normal powered operation. Check the voltage again after the controller has been running for 4–6 hours; a healthy cell will read at or very close to 3.6V at that point.