The failures
- UCTRONICS UC-3AF-USBC 2.4A
- UCTRONICS UC-3AT-DC 4A
- REVODATA TYPEC0503G 3A (SDaPO Type C0503G 3A)
- REVODATA TYPEC0504G 4A (SDaPO Type C0504G 4A)
- PoE Texas Power for USB-C 3A (SDaPO Type C0503G 3A)
- PoE Texas GAT-USB V2
- Intellinet Gigabit Ultra PoE (561693)
There seem to be two large manufacturers of what I would categorize as the inexpensive splitters, UCTRONICS, and SDaPO. Both are commonly relabeled by a lot of other "manufacturers." The SDaPO units in particular seem to underlie much of the market, and are sold under a bunch of names--sometimes including text like "C050X" in the part number, but not always.
The failure symptoms for the splitters are not all the same. The UCTRONICS units generally show immediate problems with Z-Wave transmissions, easy to see with a sniffer. Z-Wave packets suffer significant delays coming out, and attempting to send a large number of Z-Wave packets in quick succession can cause Z-Wave lockups, sometimes lasting for a minute or more. But the hub does eventually recover.
The SDaPO units do not show immediate problems, however the Z-Wave power of the hub appears reduced. Some devices that are on the edge of direct reach when using the brick become one hop when using the splitter. Nothing outright fails, it just doesn't work nearly as well as with the brick. And again, pounding out a large number of packets exacerbates the problem. But they probably work well enough for most folk. Honestly, if I didn't have some temperamental 300 series devices, or spend so much time looking at Z-Wave strength and routes, I would probably not know that they are lacking.
The UCTRONICS UC-3AT-DC 4A and the REVODATA TYPEC0504G had been returned prior to the scope multimeter arriving, so I do not have graphs of those. Just the gross statement of "I see a lot of voltage fluctuation" using the dumb meter.
Here is a graph of what the test looks like on the UCTRONICS UC-3AF-USBC:
The voltage is a bit unstable and suffers drops when the power draw spikes.
Here is a graph of what the test looks like on the SDaPO / REVODATA / PoE Texas Type C0503G:
While the base voltage is higher, similar to the UCTRONICS unit the voltage is unstable and suffers drops when the power draw spikes.
The Texas PoE GAT-USBC V2 was a spectacular failure. Here's what the graph looks like:
Graph doesn't look that bad, right? The hub even functioned okay, about as well as the REVODATA units. The key problem is that the PoE device actually requires some form of USB power negotiation, and will not work without it. So the splitter works okay as long as the multimeter is in-line because the multimeter provides the negotiation, but if the multimeter isn't there then the splitter will not power the hub. Total fail.
The Intellinet Gigabit Ultra PoE (561693) was also a spectacular failure. I had high hopes for this unit, but it simply would not power the hub, even with the meter in-line. I tried connecting an iPad to it for testing, and it just cycled between power and no power every couple of seconds. It's possible that the unit was simply defective.
