The 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.

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ButlerianJihad a day ago | parent [-]

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.

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mischanix a day ago | parent [-]

Counting mains power cycles is an adequate clock with a 0 of whenever it was last closed in. That 0 could conceivably be correlated to an hourly schedule if that process is automated. Not saying it’s common, but signals don’t have to come from the network.

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