Battery lithium 3V CNC CONTROL CR17450SE-R Replaces: A02B-0200-K102, A02B0200K102, A98L-0031-0012, A98L00310012, CR17540SE-RL, CR17450E-R-CX BACKUP BAT FOR FANUC 16i, and 18i, and 21i. Very important battery sits hidden, FANUC control To be changed once a year = high security to avoid losing machine data should be replaced only by authorized service personnel