Asked
Viewed 28 times
1
1
I was thinking about an 8 port switch that can provide my 8 RPi’s 4 power over POE.
I think i have found one according to my needs ( small dimensions), namely the: Ubiquiti EdgeSwitch 10XP – https://www.ui.com/edgemax/edgeswitch-10xp/
With a PoE budget: 150W
Would this be sufficient?
-
Well, it depends on the current you are driving the Rpi 4’s. Suppose the PoE voltage is 40V, and each Rpi is sinking 1A, then the total power is 40 x 1 x 8 = 320W, and the switch might explode! 🙂 – tlfong01 Oct 29 at 0:31
-
@tlfong01 This cannot be true. The RasPi is consuming 1-2A on 5V not on 40V. – Ingo 4 hours ago
-
@Ingo, I am very sorry. I made a silly careless mistake. I forgot the Rpi PoE HAT has a switching power supply, converting 40V DC to 5VDC. Now let me do the arithmetic again: (1) The power required for 8 x Rpi’s = 8 x (5V x 2.5A) = 80W. (2) However the 8 port switch is powered by an AC/DC adapter of 24V 1A = 24W. (3) Therefore, very very roughly the 8 port switch can only entertain 80W / 24W == 4 Rpi’s. (4) But there is another BIG PROBLEM : the switch PoE voltage is only 24V DC, but Rpi PoE HAT requires 37V – 57V. In other words, the SWITCH IS NOT COMPATIBLE TO to Rpi HAT! – tlfong01 9 mins ago
-
These are the references I googled: (1) EdgeSwitch 10X/XP (External Power 24V DC 1A AC/DC Adapter, All RJ45 Port Output 24V Passive PoE) Datasheet – Ubiquiti Networks dl.ubnt.com/ds/edgeswitch_x_ds (2) EdgeSwitch Config Interface V1.8 UserGuide – Ubiquiti Networks 2018/2019 dl.ubnt.com/ug/edgeswitch_ug.pdf (3) Rpi3B+/Rpi4B PoE HAT (Switching Power Supply 802.3af PoE, Input 37–57V DC, Output 5V/2.5A DC) rpi.org raspberrypi.org/products/poe-hat / to continue, … – tlfong01 8 mins ago
-
(4) Rpi3B+/Rpi4B PoE HAT Product Briefs – rpi.org static.raspberrypi.org/files/product-briefs/… – tlfong01 7 mins ago
-
@NicoJuicy, I am very sorry to have made a careless mistake of calculating the power requirement for the 8 port switch. I did the arithmetic again and found that the switch can actually PoE power 4 x Rpi’s. But there seems to be a big problem: the switch’s PoE voltage is only 24VDC, but Rpi PoE HAT requires 37V~57V. In other words, the switch is NOT compatible to Rpi PoE HAT. This time I am still doing very quick and dirty calculations, so I don’t guarantee that I am not making more mistakes! 🙂 – tlfong01 5 secs ago Edit Delete
.END
Categories: Uncategorized
