Recommendations for Changing PLC Batteries

[emunoz]

We are doing an inventory in our plant of all current PLC, after we had a bad experience with a Modicon 984 / 680 losing its program after the PLC battery ran down.

Fortunately I was able to locate a person in Xcel Controls, makers of the Up / Doc program we used to load the Ladder Logic; he helped me understand how to use the program even though they have not sold the program in 10 years.

We would appreciate feedback of the best method for changing batteries in the following models (For ex. power down, don't power down, etc.):

Siemens IS 307 dated 1997
Omron R885 3060 dated 1997
Asea Brown Boveri (ABB) ACS 600 dated 1997
Allen Bradley, model SLC/03, Serial: P!-0595N-3433 dated 1997
Allen Bradley, PLC2 / 20 1772 dated 1980 +/-

In this last case (PLC2) we do not have a backup program (only a hard print out). If we have to power down, would it be a good idea to feed the batery terminals wih 7,2 volts of DC before removing the old batteries and insert the new ones carefully ?

Also how frequently should these batteries be changed ?

Thanks for the help,

emunoz

 

[TConnolly]

You can find the manuals for the PLC/2 here (there are four pages of links) Publication 1772-6.6.3 includes detailed instructions on how to change the battery. The battery is located behind a cover on the power supply. Its not necessary to power down the PLC/2 to change the battery - in fact, you must leave it powered up if you want to preserve the program.

The SLC5/03 has a small capacitor that will preserve processor memory contents for several minutes while the battery is disconnected for change out. Manuals for it can be found here.

 

[magicsmoke]

At our plant we have a P.M. to change out the batterys every year on slc's, plc 2's, plc 5's and plc 4's. Don't want to take any chance's on down time because of a battery.

 

[Mark Buskell]

I was at a place yesterday and ask about their battery's. They also have a policy of changing them once a year.

That does remind me of one of my customers. The PLC-5 battery low light came on. They decided to kill power first and then change the battery. Lucky for them, we had a backup of their program.

 

[parky]

Iv'e been in plc control for over 25 years, most plc's batteries will last between 5 & 10 years if they are mostly powered up, however if the plc is powered off for long periods then I suggest you change the battery every year at least.

If like on many plants the plc is rarely powered down then 2-3 years will be the norm.

By the way many plc's now will hold the program without battery for half an hour (they recommend 10 mins).

Mitsubishi however will hold for days, I had one a series A and a q series that someone had left without batteries (test rigs) for over 5 days & the program was still there?
Also I suggest if you have HMI's fitted then an alarm be generated on low battery or at the very least a spare output onto a lamp so a visible indicator will tell you if battery is low.

 

[careed_25]

I like the idea of using an hmi to warn of a low battery. My question, after searching the help files in logix 5000, is where does the status bit for a low battery reside within the controller data? I mainly use compactlogix l32e and controllogix processors.

 

[TConnolly]

I like the idea of using an hmi to warn of a low battery. My question, after searching the help files in logix 5000, is where does the status bit for a low battery reside within the controller data? I mainly use compactlogix l32e and controllogix processors.

Use GSV to retrieve the minor fault bits. Battery status is bit 10. See attached. I don't know what version of L5K you are at so I saved it in the lowest rev. I have installed, v13 - upconvert it if you need to.

 

[careed_25]

Use GSV to retrieve the minor fault bits. Battery status is bit 10. See attached. I don't know what version of L5K you are at so I saved it in the lowest rev. I have installed, v13 - upconvert it if you need to.

Thanks for the info, I figured I was going to have to use the GSV but I searched the help files and never ran across what object instance to look at needless to say which bit I need. Thanks again this will be very helpfull. We have near 50 plcs combination of compact and control logics and implementing Studio SE system by end of year. This will help avoid having to travel over 20 miles of underground beltlines to manually check the bat stat light.

 

[Jeebs]

We like to change the batteries every 2 yrs.

With the Siemens it's fairly easy:
-Make sure the machine is up and running
-Remove old bettery
-Insert new battery

If you think it be better to power down the machine before removing the battery then you don't really understand why the PLC needs the battery. (It being to power the memory, making sure the program doesn't go byebye when the PLC is powered down)

I think for the other PLC's it'll be much the same: PLC needs to remain powered up when batteries are changed.

 

[CharlesM]

In the plant I worked in we shut down every year to clean our switch gear. I always made a point to change batterys before the shut down.

 

[PLC GURU]

We have SLC 505' and PLC-5's we change the batteries every 3 years. I've never had a PLC have a low battery warning changing them every 3 years. the SLC you WILL have to power down the unit to change the battery as its located toward the back of the unit (after you pull it). The PLC-5's can easily be changed with poer applied (the battery is located in the front). I'm not sure about PLC-2's though. I'm sure it works well but what a dinosaur!

 

[emunoz]

Thanks for all the recommendations; the norm seems to be 1 year between battery changes.

In the case of the Allen Bradley PLC2 / 20 when we opened it, we saw that it had two alkaline D size 1.5 batteries. We thought that it was a mistake, because I believed that a rechargable battery was needed, but after took a look at the link posted by Alaric, Allen Bradley has two options for this PLC, Lithium and Akaline batteries, both non-rechargeable


Regards,
emunoz

 

[emunoz]

Non Rechargeable Batteries for PLC

As a follow up to this post we would like know if there another PLC in the market, such as the Allen Bradley PLC2 /20, that uses non-rechargeable batteries (Alcaline or lithium).

What would happen if I use rechargeable batterie in this application ? I would think that the circuit that is connected to the battery is not designed for charging the battery (maybe the current only flows from the battery to he PLC) and it would not work properly, the battery would lose its charge in several days or weeks.

Any comments ?

Regards,

emunoz

 

[tragically1969]

As a follow up to this post we would like know if there another PLC in the market, such as the Allen Bradley PLC2 /20, that uses non-rechargeable batteries (Alcaline or lithium).

What would happen if I use rechargeable batterie in this application ? I would think that the circuit that is connected to the battery is not designed for charging the battery (maybe the current only flows from the battery to he PLC) and it would not work properly, the battery would lose its charge in several days or weeks.

Any comments ?

Regards,

emunoz

Schneider PLC's use Non-rechargeable batteries, as do Mitsubishi

The battery only holds the program up while the PLC is off, the power to do so is so small that it will hold up for more than a few days (i dont know an exact timescale)

If you need permanent non volatile backup look for an EEprom solution such as the Mitsubishi's

 

[parky]

Mitsubishi will hold the program for days.

It will definitely hold a program for over 5 days when battery removed, even the old omron S6 held it for a few hours.
However on siemens I allways replace the battery while powered up.