Persee RTC resets after unplugging

Persee Real Time Clock resets back to 2015 every time the device is unplugged and plugged again. I just bought this Persee recently.

Does everyone have the same problem? Can anybody answer please?

I believe it is simply because it has no battery to save clock date. They rely on network time protocol to update it.

I’m using Ubuntu 16.04 here. I never payed attention to the time of Persee, but in fact it keeps RTC after unplugging.