Problem solved: failing battery causes loss of important data

It could happen to you: thanks to a dead back-up battery, your machine has lost all of its important data. That means production downtime. In this interview, our field service engineers Robin van Buuren and Arnoud Schraa explain how this problem can be prevented very easily.

What industrial electronics have batteries?

“Basically, any module without a flash memory or external storage card needs a back-up battery. This is because RAM (Random Access Memory) 'saves' its memory only when the power is kept on. This is mainly the case with older electronics. We often see this out in the field. Newer electronics are, as a rule, equipped with flash memory which 'holds' its memory even when the power is off. This applies to all kinds of electronics: from PLC and HMI to drives and robotics.”

What is the function of such a battery?

“The battery keeps the memory part running. Without a battery, there is a greater chance of memory loss. This is because the battery ensures that when the machine is disconnected from the power network, the memory retains a small amount of voltage so the data is not lost. Operational electronics do not function without a program or parameters, causing the process to grind to a halt.”

So the risk is that a failing battery will cause data loss?

“Correct. If no back-up is available, electronics will lose the program completely or the program will become corrupted. The machine or system will then no longer work. Some machines have multiple RAM cards with individual back-up batteries, so part of the program may be lost.”

Do you ever come across this in practice?

“Just last year we had a customer who switched a machine on again after the construction holiday and only then realized that it should never have been switched off. The entire memory of the PLC was empty because the power had been turned off during the holiday and the battery was dead. Fortunately, this customer had a back-up, so he was quickly up and running again.
We would therefore like to offer an urgent piece of advice: make preventive back-ups to avoid downtime. And check to see if a memory card might be a solution. In some cases, that is the solution and the program can be stored on it without a backup battery."

What kind of batteries are we talking about?

“That varies by brand and module. In most cases, they are lithium cells with low internal discharge. Sometimes they are round, cylindrical batteries, button cells or even just AA batteries.”

When should a battery be replaced?

“That depends on the electronics manufacturer's advice. It is usually between two and five years, but it depends on the type and capacity of the battery and the amount of RAM that needs a continuous supply of power. For this reason, it is usually wise to check the battery every year. That's also what we advise.”

Does the machine provide any signs that it is time to replace the battery?

“Some modules have a light or status display that says ‘battery low’. Otherwise, testing with a multimeter is another option. Newer modules provide an on-screen notification. When preventive maintenance is performed, the date of battery replacement is tracked.”

How does replacing a battery in industrial electronics work?

“In most cases, it's very simple, just like the remote control at home. The manufacturer's manual will tell you which battery it contains and how to replace it. It's a good idea to check in advance which battery is used. Make sure to check whether a back-up needs to be made before removing the battery. A common mistake is turning off the machine before replacing the battery. You should absolutely not do this, because the program will then be lost.” 

Are there any factors that affect the lifespan of batteries? 

“Using the machine has the biggest effect, but a battery also discharges very slowly by itself. Even if the module is never turned off, the battery can still run down, so it is important to replace them punctually. In addition, extreme temperature variations or very cold conditions can affect battery capacity.”

What is UNIS Group's advice?

“Include checking batteries in the preventive maintenance list. Identify what batteries are there, whether they work and when they need to be replaced. If your own technical department cannot take care of this, you could hire an external party, such as UNIS Group, to perform maintenance during a planned production shutdown, for example. The magic word here is preventive. Unfortunately, a dead battery is often not noticed until it is already too late, because as long as the machine still has power, it will continue to do the job.”

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