Fanuc OM Battery Warning Wont Clear

I have a Fanuc OM control that says BAT at the bottom of the program screen I assumed it was a reminder or warning my batteries were low so with the control powered on I put in new batteries but the BAT does not go away. Is there something I have to reset? I am scared to turn off? I have checked polarity to confirm I installed the batteries correct. Any thoughts would be appreciated

Most machines have more than one battery. How many and where is determined partially by the machine builder and how the machine is configured. Need to find all and change them.

I found one compartment for 3 D batteries everything I have read now tells me there should be another compartment with 4 D batteries but I have searched high and low and no luck finding it. Anyone familiar with Daewoo ACE-V40 mill battery locations with Fanuc OM control? I have come to the point where I have shut down the machine and backed everything up hoping for the best.

Not familiar with your machine, but I just changed the batteries in my NTC vmc with Omb control.
2 battery compartments

Did you hit the reset button after installing the new batteries?

When I started thinking I was changing batteries to often ,I started marking the change date right above the battery compartment in sharpie
I get a little over 2 years a set with name brand D cells

I have an OM-B as well and my manual for the Fanuc side of things references 2 compartments so I’m pretty sure there has to be one somewhere. I have hit reset and cycled power still no luck which also confirms in my mind that there has to be another set of batteries somewhere just for the life of me cannot find them. Is anyone one here a Daewoo/ Doosan service guy or own an older Daewoo vmc?

tquinn said:

I found one compartment for 3 D batteries

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The three D cell holder is the CNC memory. Be sure the batteries are inserted correctly. IIRC the outer ones are positive up and the center is positive down. I have also seen several of those battery cases get corrosion on the terminals from leaking cells. Worth checking for sure. There should be a couple screw terminal on the back of the holder. With fresh batteries you should see no less than 4.5V. If all that checks out and you can not clear the battery alarm then you need to check the voltage where the battery unit cable connects to the memory board. Per the maintenance manual for a OMC that connector will be labeled CPA7.

tquinn said:

.....everything I have read now tells me there should be another compartment with 4 D batteries but I have searched high and low and no luck finding it.

Click to expand...

The 4 D cell battery unit is only used if the machine is equipped with absolute encoders. It has been so long ago that I last worked on an ACE30 that I do not remember if Daewoo used them or not. If you have to reference return the machine each time you power it up before running a program then it probably does not have absolute encoders.

Thanks for the info I believe I have incremental encoders since I do home each time after startup so at least I not blind there must only be one battery set. I still get the BAT light and confirmed that I have 4.8 VDC at the end of the cable where it plugs into the memory board. I hit reset BAT goes away for a period of time then returns...not sure where to go from here. I had the machine powered off over night and no issues it seems. Is there a capacitor that charges also to save memory? Wondering if the board could be bad?

I may have figured it out! Plastic Connection at the board seemed loose so on the wire side I slightly distorted the terminals to increase contact pressure. Bat light stayed off and I powered down will try later today just to see if it worked. Still am curious if there is a capacitor that is a secondary backup? Thanks Vancbiker for the info on absolute enconders

As far as I remember there is no secondary backup like a capacitor. If you lose battery connection while the control is off, you lose the memory.

I heard about "super capacitor."