Conflicts with PD USB Docks?

[ravenium]

I just noticed something this morning - when my Mac (M4 Air) is "holding" (e.g. not charging the battery), certain USB Power Delivery (PD) accessories do not seem to work properly when plugged in.

For example, I have a mini USB Dock (DockCase) with Ethernet/multiple USB Ports, plugged into one of my two USB-c ports. If I have items plugged into the dock's USB ports when I plug it in, it enters a state of continual reboot.

If I unplug the USB items from the dock, plug the dock in, then plug the USB items in, it works fine.

If I disable Battery Toolkit (or if it is in a charging state, such as "charge to full"), this does not happen and I can plug in the dock with accessories connected.

It's not a big deal, but it seems like there may be an issue with how PD is being negotiated - or the fact that the Mac is thinking the Dock itself is a charging source, since there is a USB-C passthrough port? (note that I don't have any chargers connected to the dock when I do this, just the magsafe port).

Let me know if I can help provide any diagnostics or troubleshooting!

[mhaeuser]

BT doesn't have low-level control over any of this. Hard to tell for sure, but you might hit the same issue when macOS' Optimized Charging puts it on hold.

[ravenium]

I've got an M1 that sits at my desk most days - I'll try it on that when it gets to hold mode. Thanks!

[Adifagos]

You know, i hadn't realised 'til now, but the OP's spot on :)

Have had an issue where my external USB NVME (Icy Dock with a 2TB Samsung 970 EVO) enclosure would occasionally not be recognised when i plugged it in.
Tried what the OP describes and yeap, issue!

Good catch.