SIM800C losses time after power off!

Hi all,
I have a strange problem with the SIM800C about the timing. More specifically it seems that the SIM808 RTC module losses many minutes when the module is power off.
I had tested with 24-hour power off and after the power on the SIM800 gave me the time with 40min elapsed from the real time!
The battery for RTC was 12-20 type.
In the past I had worked with father of SIM800 the SIM900 and I had no problem with the RTC time.
Do you have faced any problem with RTC timing of SIM800C?
Any suggestions,
Thanks,

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.