Date/time loss problem. Who can help me?

I have hundreds of up boards installed for a few years, some of them are starting to lose the time and date. I tried replacing the CMOS battery to fix the problem but to no avail... Has this happened to anyone? Does anyone have any suggestions?
Answers
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Hi @alexxx82
Please check if the RTC battery still has power.
The voltage should be approximately 2.8V or higher.Best Regards,
Harry Chiu -
Hi Harry,
I replaced the battery with one (many more than one) that worked, but the problem persists. I currently have five other PCs that no longer work properly. I'm worried because I have about 800 units installed, and if I don't find a solution, I'm done for. -
Hi @alexxx82
Removing the RTC battery clears the CMOS, thus resetting the time.
After clearing the CMOS, the time must be manually reset.What is your operating system?
How significant is the time difference?Best Regards,
Harry Chiu