alt Hacker NewsThe external sync here is NTP. Synchronized clocks + timer-scheduled actions → globally synchronized behavior
From the article:
> The origin of these current peaks was independently confirmed by the manufacturer to be periodic self-tests executed by the battery EMS, confirming our interpretation. Similar minute-scale diagnostic routines are also documented for other commercial UPS systems (cf. Supplementary Note 8).
https://www.snaptec.com.au/akkutec-4801-din-user-manual.pdf
> battery circuit testing 1 x per minute for 1 sec
https://adelsystem.com/hubfs/PDF%20DC-UPS/Instruction%20Manu...
> The battery testing is carried out automatically every 60 sec.
So, the two devices you refer to have no time-of-day clock, no network connection, no TCP/IP stack, and certainly no NTP clients.
Their testing on the enterprise-class equipment shows the difference that NTP makes, and with enterprise-class equipment comes wider deployment and more powerful models.
But most of the consumer units would not have this stuff. Surely, the manuals would describe how to set it up.