Early Adopters Raise a Range of Concerns with the Raspberry Pi PoE+ HAT
Deafening coil-whine, USB back-powering, excessive heat, a 60 percent increase in power draw — and components that fall off.
Early adopters of Raspberry Pi's newly-designed PoE+ HAT, which adds Power over Ethernet (PoE) capabilities to selected models in the single-board computer family, are reporting a range of teething troubles — including incorrectly-sized bolts, back-power from USB causing coil whine, fragile components, and excessive power draw.
Launched late last month as the successor to the near-three-year-old Raspberry Pi PoE HAT, the Raspberry Pi PoE+ HAT has the same purpose in mind: Allowing a compatible Raspberry Pi single-board computer to receive both power and data through its Ethernet port, while also cooling the processor through a centrally-mounted fan.
Compared to the original PoE HAT, the new model offers the ability to pull 25W from a PoE power supply, up from 15W on the original, and promises to run significantly cooler while doing so thanks to a new high-efficiency bridge rectifier. Unfortunately, early adopters are reporting otherwise.
"After the initial problems with the original PoE HAT, and the public admission they’d not tested the HAT sufficiently, you’d expect that the Raspberry Pi Foundation would be darn sure to ensure that the new Raspberry Pi PoE+ HAT met the highest design and quality standards," maker Martin Rowan writes in a review. "I accept we don’t have the same power stability issues as the original PoE HAT, but there are still some problems with this latest offering from the Raspberry Pi team."
Some of these problems are disappointing, but easily resolved — such as a 12mm fan bolt which fouls the CSI camera connector on the Raspberry Pi, fixed by swapping it out for a 10mm version, adding a second nut as a spacer, or reversing the bolt. Another, however, points to a potential design flaw: Extremely loud coil whine when a USB power supply is connected, apparently the result of failing to disconnect the PoE hardware when a local power supply is present.
Another issue is in the power drawn and heat generated: Rather than improvements on both fronts, as promised, Rowan reports a 60 percent increase in power draw compared to the original — and a corresponding increase in heat, with parts of the board becoming "too hot to touch."
Maker Jeff Geerling's experience, posted to Reddit, concurs with Rowan's on all fronts — while adding a new flaw to the mix: "The surface mount four-pin PoE header on the underside is still fragile and can separate when you pull off the HAT," Geerling explains. "This was an issue with the older HAT, and it's easy enough to fix, but sad it wasn't made stronger in this revision."
The Raspberry Pi team has not yet commented publicly on the issues.