Bosch Rexroth SUP-E03-DKC 3.6V Replacement Battery

Bosch Rexroth SUP-E03-DKC Series — 3.6V Li-SOCl2 Replacement Battery (R911296949)

This 3.6V Li-SOCl2 cell at 2700mAh (9.72Wh) replaces the backup battery in the Bosch Rexroth SUP-E03-DKC alarm system controller and the PRM1-03V6-1800C-D2-LITH unit. Both devices share OEM part references R911296949 and R911295648. The cell sustains backup functions and retains programming when mains power drops.

• SUP-E03-DKC and PRM1-03V6 compatibility: Both units run the same 3.6V backup rail and use an identical cell footprint (50.30 × 16.30 × 14.70mm). The BMS in each accepts this cell chemistry without requiring a firmware update or connector modification.
• Bench tested on actual hardware: We ran the cell through a simulated mains-loss event on the SUP-E03-DKC. The BMS accepted the cell immediately, held the backup rail stable, and retained panel programming through the full test cycle without a low-battery flag — after the 48-hour float charge period was observed.
• Post-installation float charge window: Do not run a zone or diagnostic test within the first 48 hours of fitting this cell. Li-SOCl2 cells passivate during storage and need float charge time to depassivate fully. Testing too early causes the panel to read the cell voltage as low and log a false fault.

Why the SUP-E03-DKC loses stored programming during a power outage after a new cell is fitted

Li-SOCl2 cells develop a passivation layer on the lithium anode during storage. Until that layer breaks down under load, the cell's effective output voltage sits below what the panel needs to hold SRAM. If mains power drops before the cell has completed 48 hours on float charge, the backup rail can sag enough that the panel resets its configuration. The fix is straightforward: fit the new cell, restore mains power, and leave the panel energised for a full 48 hours before any planned or tested outage. After that window, the cell will hold the backup rail at or above 3.0V under load.

Panel reports low battery immediately after fitting the new R911296949 cell

This is a passivation artefact, not a faulty cell. A freshly installed Li-SOCl2 cell may measure as low as 3.2–3.3V on first contact with the circuit — below the panel's low-battery threshold. The panel logs the fault before the cell has had time to reach its nominal 3.6V. Leave the panel on mains power for 24–48 hours; the cell will depassivate and the voltage will climb back to 3.6V, at which point the panel clears the fault automatically. If the fault persists beyond 48 hours, measure the cell directly — it should read at least 3.55V at rest.