Reply 1 (by FanucWizard_Midwest):
Losing work offsets after power cycle on a Fanuc 0i-MF is a SRAM battery problem until proven otherwise — full stop. The 0i-MF uses a lithium battery to maintain the SRAM contents including work offsets, tool offsets, pitch error compensation, and macro variables, and when that battery gets low it doesn't always throw a clean low-battery alarm before data starts getting corrupted. The battery is a standard Fanuc A98L-0031-0007 and it costs about twelve dollars. If your machine is more than 3-4 years old and you've never replaced it, do it today regardless of what the battery voltage reads because these batteries often measure fine on a multimeter right up until they fail under load. Keep a full data backup of your SRAM on a USB or through Focas before you swap the battery and the data survives the swap fine.
Reply 2 (by Kitamura_Owner_CA):
I've had this exact thing happen on our Mycenter-3XG and while the battery is the first thing to check, there's another cause that caught us off guard — the parameter that protects offset write access. On the Fanuc 0i-MF there's a write-protect parameter and if it's set incorrectly or a parameter reset happened for any reason, the machine can accept offset entries during a session but not commit them to non-volatile memory, so they survive within a power session but vanish at shutdown. Check parameter 3290 bit 0 which is the offset write protect setting and also parameter 8900 series if your Kitamura has any builder-specific macro protection active. The Kitamura documentation supplements for the Mycenter line cover these parameters pretty well and Kitamura America's tech support in Wheeling is genuinely helpful if you call them.
Reply 3 (by CNC_Maint_Foreman):
Another angle that people miss — check whether your offsets are stored in G54-G59 or in the extended workpiece offset table G54.1 P1 through P300, because on some Fanuc configurations the extended table has separate battery-backed memory behavior and separate backup requirements. If whoever set up the machine originally programmed in G54.1 extended offsets and your backup/restore procedure only covers G54-G59, you'll lose the extended offsets every time and be completely confused because the standard offsets look fine. Also in 2026 it's worth knowing that Fanuc's FOCAS2 library for Ethernet-based data collection makes automated nightly offset backups very easy to implement, and several low-cost OEE tools now include this as a standard feature. If you're on a Kitamura with the optional Ethernet card, setting up automated offset backup is an afternoon project that pays for itself the first time you have a battery issue.
Reply 4 (by ProductionMgr_TN):
To add some practical shop floor wisdom — any time you're dealing with mysterious data loss on a Fanuc control, pull up the alarm history and look specifically for 9001 or 9002 series alarms because those are SRAM and battery-related alarms that sometimes appear and clear so fast during power-up that the operator never sees them but they do leave traces in the alarm history log. Also check if your facility has any large machinery nearby that creates power quality issues because voltage spikes on the incoming power to a Fanuc control can cause SRAM write errors that look exactly like battery failure but happen even with a new battery. A UPS or a proper line conditioner ahead of the Fanuc control transformer is cheap insurance and I've seen it solve "unexplained" offset loss issues more than once in shops where the power quality was quietly terrible.
