[margo209320]

"The power adapter often can't provide sufficient power to spin everything up at boot, and needs the battery as a buffer"

Do you have any proof for that? It sounds very unrealistic to me. These days there aren't even any magnetic disks to spin up at boot time.

[magicalhippo]

Well I literally powered up an oldish laptop two days ago that had been sitting there for a few years, and it turned off three times within a few seconds of booting until I let it sit for a few minutes for the battery to charge.

The power brick is rated at 19V 3.16A output, so 60W, the CPU is a 35W TDP second-gen i3.

Of course a big part of that is spinning up the disk, so as you say I imagine this is quite different these days with SSDs.