Topic (read)Changing PLC battery questions

CarmeloLabadie said:

HI,



im a student and never experience changing PLC battery.

i have some questions in mind.



1. how will i know if the battery is low or it needs to be replaced.?

2. what if the battery is low then it was not replaced. for what point of time can it go? i mean until it will totally shuts off?

3. Can i Change the battery even with out low battery indications.? just asking



thank you for your respect and answers.

Click to expand...

parky said:

Most PLC's that have batteries will usually be good for 5-10 years (depending on how often & for how long they are powered down), for a PLC that is powered down for more than a few weeks the battery will probably last 6 months but a lot depends on the technology i.e. the drain on the battery, like as already posted, 1 year it is recommended to replace the battery. I have known systems that are rarely powered down to last 10 years plus.
Most PLC's also contain a large capacitor so in the event of a low battery it will retain it's memory for 10-20 minutes, things to keep in mind:
Replace batteries for example as a Planned maintenance say once a year, in the event of the battery low indicator (now this is a controversial one) replace the battery while the PLC is powered up, some PLC mfgr's recommend powering down & replacing within a few minutes, however, I have been replacing batteries for over 30 years & never power down (only once did I power down & lost the program), Never had any problems doing it this way. The best solution is always keep a copy of the program if possible just in case.

Click to expand...

alive15 said:

On Rockwell PLCs, they have an indicator on the PLC letting you know to change the battery. Usually it's best to replace annually even if the indicator does not come on, but I've seen some go as long as 3-4 years. If you never turn the PLC off, then the battery becomes useless anyways.

Click to expand...