About this replacement
Mitsubishi MR-J4 — 6V Li-MnO2 Replacement Battery (MR-BAT6V1SET)
This 6V, 1650mAh lithium-manganese dioxide cell replaces the OEM backup battery in the Mitsubishi MR-J4 servo drive. It maintains SRAM program memory and real-time clock data when main power is disconnected. Part numbers MR-BAT6V1SET and 2CR17335A WK17 both cross to this cell.
- MR-J4 servo drive compatibility: The MR-J4 series uses a dedicated battery compartment wired directly to the SRAM and RTC circuits. This cell matches the voltage rail, connector, and physical envelope that Mitsubishi specifies for that compartment — no adapters or modifications needed.
- Bench tested on actual hardware: We ran this cell on an MR-J4 drive and confirmed the BMS accepted the new cell without triggering a battery fault alarm. SRAM retention held across a controlled power-down cycle and the RTC continued tracking correctly after restoration.
- Hot-swap protocol for MR-J4: Always replace this battery with the servo drive powered on and in RUN mode. Removing the cell while the controller is powered off will cause SRAM memory loss — the drive will not retain its program and a full reload from the programming device will be required.
MR-J4 battery alarm not clearing after a confirmed good installation
The MR-J4 does not automatically clear a battery alarm once a new cell is installed. The alarm flag is latched in the drive's parameter memory and must be reset manually through MR Configurator2 or the front-panel display sequence. If the drive is showing AL. 92 or a battery warning LED after the swap, the cell itself is not the problem. Navigate to the alarm history and issue a clear command — the alarm will not self-cancel on next power cycle.
New cell reading below 6V on the MR-J4 diagnostic screen
Li-MnO2 cells ship in a storage state and may read as low as 5.4–5.6V immediately after installation. This is normal — the cell is not defective. The MR-J4 float circuit will bring the measured voltage up to the 6V operating band within a few hours of the drive being powered. If the voltage has not recovered to at least 5.8V after 24 hours of powered operation, check the connector seating before assuming a faulty cell.