Allen Bradley PLC batteries

Hello again
As always thanks for being there. In my plant I am the only PLC/Control person and I use this forum quite a bit just so I can find someone speaking the same language.
My question for today has to do with Allen Bradley PLC’s batteries.

1) SLC 5/05 Processors (1747-L552 to be exact)
I was told that these batteries have no type of recharge while installed in the SLC. (True or False is the question here?) As well as that the SLC will / should hold it’s programming for the few minutes that the processor will be without power while a new battery is installed (same here is this true or false?)

2) PLC 5/40E (1785-L40E )
With this Processor I was told that if I remove the battery with no power to the processor that all the programming would be lost. (Again my question is true or false?)
I was also told that the PLC5 is designed to have the battery replaced while the processor is powered up i.e. 120-volt power applied to the rack (as seems to the theme of the day. True or false?)

We are scheduled to have a contractor come in on Wednesday for preventive maintenance to our high voltage system. I was planning to also replace batteries during this down time as well.
I will of course have as always a backed up copy of all programs (Ladders) just in case something goes wrong because here it seems something always goes wrong.
As always thanks for the help and thanks for just being members of this great forum
Michael

With the SLC 5/05, you are correct. From the SLC User Manual:

The SLC 5/03, SLC 5/04, and SLC 5/05 processors
have a capacitor that provides at least 30 minutes of
battery back-up while the battery is disconnected.
Data in RAM is not lost if the battery is replaced
within 30 minutes.

Click to expand...

With the PLC-5 - you are also correct - if you kill power with no battery, your program will be gone. Batteries can (and should) be replaced under power.

Whenever you remove the batteries, I agree with you that it is always a good idea to have the backup!

Marc

The PLC-5 has the battery right on the front of the unit so it was never necessary to power down to access it. Therefore no capacitor was necessary.

The 30 minutes of backup was a necessity with the 5/03, 5/04. 5/05 since the unit had to be powered down to access the battery.

If you run across an SLC 5/01 or 5/02 you will notice that those units have the battery on the front and there is no capacitor. So like the PLC-5 it was designed to have the battery replaced while power is applied.

The 5/03, 5/04, and 5/05 had to have their batteries relocated due to space limitations (my speculation) when the RS232 port was added.

OG

Thank you both

I just wanted to thank you both for confirming what I had already thought.
It never hurts to double check things.
thanks again
Michael

Operaghost,

Good point on the SLC 501 and 502: DO NOT kill the power to replace the battery! Even for the 503 and 504, be very quick when you change those batteries!

Last month I got a call from an electrican at a lumber mill. They had shut down their steam boiler for maintenance, and while the SLC503 was powered down, he thought it would be a good time to "check the battery" in the PLC. Now he wanted to know why he couldn't restart the system!

I had to go up there and help him reload the program.

Whenever we install a PLC5 (we dont use SLCs so im not sure if the same can be said, although I imagine so) we install a stacklight on the MCC with a green lamp and an amber lamp, the green lamp is to indicate that the PLC is in run mode (or rem run mode) and the amber light is to display a battery low condition (one of the S status bits dont have it on hand at the moment Im sure Ken or one other the other AB knowledgeable guys will know) this gives visual indication of the low battery condition.

We also program an alarm in the HMI if fitted.

I have been amazed at all the facilities that I have come across that have no backup program. Even when the controls were designed and built in house. I have seen many programs that were wrote on the back of a schematic.

Sometimes, all the electrician has is a handheld programmer, so I can sympathize somewhat. But still, a a hard copy of sometype is neccessary.

I like to make an owners manual for each machine in a plant, with a copy of the schematic, program, lock out tag out, and manuals for oddball stuph, like vibratory feeder bowls or electric brake units, and a general parts list, like I/O modules, bulbs, fuses, etc.

I have found this helpful, with the turnover of help getting higher and higher.

Bottom line....

1). Be sure batteries are good, or changed regularly, or at least have a spare on hand.

2). Always have a PLAN B, a backup program or hard copy.

3). Never trust the program to remain when changing a battery, or during a routine shutdown.

4). Try to power down each plc prior to a shutdown, and power up AFTER power has been restored. Saves a lot of problems in the long run. I can't begin to remember how many programs I've lost do to a power surge, spike, or brown out.

For fun, ask the "new guy" to call the power company and request a 30 minute warning on ALL POWER OUTAGES, including drunk drivers hitting power poles. I worked as a technical guru for a police department one time where the chief wanted the power company to give a one hour advance warning so the on-call tech could be present before the stand-by generator would start up.

best regards.....casey