About this replacement
Motorola R2600 / R2660 / R2670 — 3.6V Ni-MH Replacement Battery
This 3.6V 150mAh Ni-MH cell replaces the backup battery in the Motorola R2600, R2660, R2670, and PMB3.6b industrial control modules. It maintains the real-time clock and SRAM memory during mains power loss. Without a functional cell, the PLC loses system time and stored configuration data every time power drops.
- R2600 / R2660 / R2670 / PMB3.6b compatibility: These modules share the same 3.6V backup rail, connector footprint, and BMS float-charge circuit. One cell spec covers all four variants without modification.
- Bench tested on actual hardware: We cycled this cell through the R2600's float-charge circuit and confirmed stable voltage delivery to the SRAM and RTC registers. The cell held within spec across repeated charge and simulated power-loss events.
- Hot-swap procedure for the R2600 series: Always replace this cell with the controller powered on and in RUN mode. Removing the battery while the PLC is de-energised will cause SRAM memory loss. If the controller was off during the swap, a full program reload from a connected programming device is required before the unit can return to service.
PLC losing program memory after battery swap on the R2600
The R2600 uses static RAM to hold the active program image. SRAM requires continuous voltage from the backup cell to retain data — even a two-second gap is enough to corrupt or erase it. If the cell was removed while the controller was powered off, the SRAM contents are gone. Recovery means reconnecting the programming device and reloading the last saved program from your backup file. This is not a battery fault — it is a consequence of a cold swap on this architecture.
Battery alarm not clearing after a confirmed good installation
The R2600 latches the low-battery fault in firmware — it does not clear automatically when a new cell is fitted. After installing the replacement with the controller live, navigate to the fault log in the programming software and issue a manual fault reset. If the alarm persists after reset, check that the new cell voltage has risen above 3.4V on the controller's diagnostic read-out — a freshly shipped cell may sit at storage voltage and needs a few hours on the float charger to reach full charge. Confirm the cell is seated and the connector is fully engaged before resetting again.