How to Fix the Battery-Down Error in CNC Machines – A Step-by-Step Guide

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Introduction

Table Of Contents
  1. Introduction
  2. Understanding the Error & Alarm
  3. Considerations before changing batteries.
  4. How to change the battery of the Fanuc servo driver?
  5. Summary

In this article, I will show you how to fix the battery-down error that we often encounter in CNC machines. No matter what brand of CNC machine is, we can keep the position of the X, Y, and Z axes in memory even if there is no electricity, thanks to these batteries.

You will see pictures and usage best practices of batteries in this article, but remember, you should be special to your machine brand and model. Check with your supplier.

If you encounter this problem, the brand and power of the battery you will use should be in the specifications recommended by the manufacturer.

Understanding the Error & Alarm

At mechutopia.com, we approach everything by understanding and solving problems. So let’s understand a little bit about the root of the problem.

What is the voltage of Fanuc CNC battery?

 Generally it is 6 Volt, new model drivers can have specific voltage.

As far as I have learned from my experience, these batteries last for about 1 year (12 months), so usually the workshop managers change the batteries before the Christmas holidays without getting any errors.

So what makes these batteries so important? Every day when we turn off the CNC machines, all the electrical current in the electrical panel goes off. At this time, CNC machines should keep the x, y, and z positions in their memory so that the machine can go home position safely when it is turned on again.

Encoders in CNC motors need this position information, especially if your machine is running with an absolute encoder. Because incremental encoders find the position with home switches and rewrite it to the memory.

But CNC machines with absolute encoders do not need to go to the home position when they are turned on every morning, because the position is stored in the memory and the position of the absolute encoder is compensated from memory.

Considerations before changing batteries.

The user guide for batteries is very informative.

This is very important, if you get the error battery low or the battery gone, never turn off the CNC machine. If you close it, the next time you open it, a lot of errors will occur because the machine will not be able to find its home position.

In that case, your machine technician must manually move the machine to the home position, which is the production setting, and install the batteries at that point. This requires access to plc programs and parameter settings. That’s why you have to change the batteries before turning off the machine.

How to change the battery of the Fanuc servo driver?

Step-1: First of all, you should open the electrical panel without turning the circuit breaker (without turning off the machine). There is a hidden hole in these on-off switches, through which you can open the cabinet without turning off the machine, usually with a screwdriver.

Use Screw driver to open door
Use a Screwdriver to open the door

Step-2: The batteries were attached to the driver with clips, so you would have to cut the clips with a side cutter. Then you should remove the cable that connects the socket of the battery to the driver by pulling it slowly.

CNC-Batteries
Take out the yellow batteries and sockets on the end of the red-black wire.

Step-3: Put new batteries in and be sure to attach them to the driver with clips.

Step-4: Repeat until step-3 for each axis servo driver. Do not forget that, the spindle does not have a battery generally. Check with your machine manufacturer to be sure.

Step-5: Some servo drivers can be different, in this case, there was a different driver, and it had a different battery. So check your system If needed.

Different servo driver and battery.
Different servo driver and battery.

Step-6: After changing all batteries you can close the panel door and turn it off and then turn on the CNC machine again. You will find alarm end errors cleaned.

How long do Fanuc batteries last?

 Fanuc batteries if mounted to a driver can last long between 9-12 months, shelf storage time is nearly 10 years.

Summary

Never turn off the CNC machine if you receive the error of a low or dead battery. Turning off the machine may result in several failures since the machine will be unable to locate its position and will need to be manually moved to production mode. You can avoid these problems and save time and effort by changing the battery before turning off the CNC machine.

Finally, resolving the battery-down alarm in your CNC machine is critical to its precision and reliability. You can ensure that your system functions smoothly and without mistakes by following the advice offered in this article.

By Isaac Aloyan

Isaac Aloyan is a talented mechanical engineer with a background in machinery design and manufacturing. He completed his diploma from the Department of Machinery Design and Manufacturing at Kocaeli University and also graduated from Level 7 NZDE Mechanical Engineering at Manukau Institute of Technology (M.I.T). Isaac has developed strong expertise in various areas of mechanical engineering, including CNC programming and machining, vacuum mold design and production, manual machining, CAD and CAM, and thermoforming machine design and production. Also, he has educator experience in the area of CNC machinery and programming and mechanical design. With two decades of experience under his belt, Isaac has established a website called mechutopia.com to share his knowledge and help others who are interested in the field of mechanical engineering. The site is likely to feature a wealth of information, resources, and tips for those looking to learn about CNC machines, machining, mold production, and more. It is a testament to Isaac's dedication to the field and his commitment to helping others excel in sub-domains of mechanical engineering like design and manufacturing.