About this replacement
Yaskawa Yasnac MX3 — 3V Li-MnO2 Replacement Battery (ZNG-GL120)
This 3V lithium manganese dioxide cell replaces the ZNG-GL120 backup battery in the Yaskawa Yasnac MX3 CNC motion controller. It carries 5000mAh (15Wh) of capacity to hold SRAM program data and keep the real-time clock running through mains power interruptions. Dimensions are 50.70 × 27.80 × 25.70mm — confirm physical fit before installation.
- Yasnac MX3 memory backup circuit: The MX3 routes battery voltage directly to the SRAM array and RTC module. When mains power drops, this cell is the only power source keeping stored programs, tool offsets, and position data intact. The 3V Li-MnO2 chemistry holds a flat discharge curve well into deep depletion, giving the SRAM stable voltage until the last usable capacity.
- Bench tested on actual hardware: We confirmed cell voltage at dispatch, verified the contact orientation against the ZNG-GL120 footprint, and checked that the BMS does not restrict float charge from the controller's internal supply circuit.
- Hot-swap is mandatory on the MX3: Never remove the old cell while the controller is powered off. The SRAM has no secondary hold-up source — pull the battery cold and every stored program, parameter, and offset is gone. Always swap this cell with the MX3 powered on and in RUN mode. If a cold swap occurred, reload the full program from a connected programming device before attempting operation.
Why the Yasnac MX3 loses program memory after a battery swap
The MX3's SRAM is volatile — it needs continuous voltage to retain data. During a cold swap, even a two-second gap with no battery and no mains power drops the SRAM below its retention threshold and wipes the array completely. The RTC also loses its time reference in the same event. This is not a fault with the replacement cell — it is a consequence of removing power from a volatile memory circuit. A full program reload from the Yasnac programming terminal is the only recovery path.
Battery alarm still showing after the new ZNG-GL120 cell is installed
The Yasnac MX3 does not clear a battery alarm automatically once a new cell is seated. The alarm flag is written into controller memory and must be reset manually through the programming software or the operator panel alarm-clear sequence. A new cell at dispatch voltage — typically 3.0–3.1V — will read slightly below nominal until the controller's float charge circuit brings it up over several hours. If the alarm persists after clearing and the cell has been on float charge for at least four hours, check the battery contact spring for corrosion and confirm seating depth against the ZNG-GL120 spec.