Hello!

I have a question - can I use a 12V power source to power the 750UP and then feed a 532, a 750G and a 751(U/G) over PoE with it? I am asking because the 532 accepts only 12V or 48V over PoE and the latter is out of question as it will fry all the other RB - 750UP included.

If I can use a 12V PS, how many amps should it be able to produce?

Thanks in advance!

P.S. I know the manual says 8-28V iz OK for the 750UP, the 750G and the 751 but I want to be on the safe side...

newer boards (700 series) works starting from 8V, poe-out cut off due to low voltage happens around that range too.

you just have to see what are power requirements for the boards as maximum is well over 500mA limit if you are going to use 12V PSU to power the RB750UP. For example, RB751G at max without USB module will consume 11W @24V with maximum being 14W at lower voltages at full tilt (both values) you can configure wireless to use less power and not use all the gigabit ethernet ports.

how about connect 2 12V batteries in series?

From the RB532 manual (see bold text):

RouterBOARD 500 series boards are compliant with IEEE802.3af Power over Ethernet standard and accept
48V powering over up to 100m (330 ft) long Ethernet cable connected to the first Ethernet port (J6). The
board also accepts 12V DC (or any other within the 11..22V range) non-standard PoE input voltage (see
note above on how to use it)

Thank you both for your answers!

So no, I can't use a 12V PS as I want to be able to use the wgole 751Gs potential.

As for the excerpt normis quotes, I have found something different elsewhere:

PoE
IEEE802.3af Power over Ethernet (both JP5 and JP6 must be switched to the 2-3 position) accepts 12V or 48V DC powering depending on the position of JP3 and JP4.

and

The first Ethernet port is compatible with IEEE802.3af Power over Ethernet standard and passive PoE (non-standard). The
board accepts either 12 or 48 V DC input voltage according to the configuration (see Powering section of this manual on how
to choose the PoE option and select voltage).

This comes from ftp://95.174.38.7/Drivers/Mikrotik/rb%2 ... _guide.pdf

As for the 6-22V, the manual quoted above states that this voltage can be applied, but to the power jack and not the the PoE Ethernet port. How about that?

You can read again my pasted quote. It's from the most official of all official sources. I represent MikroTik and can guarantee you, that PoE also accepts this range - we just tested. in 12V jumper mode, PoE worked from 6V to 20V, in 48V mode, it worked from 20V above.

Thank you for checking that for me normis! It know you represent MT but i wanted to be 100% sure. The RB532 is not exactly mine and I received it along with the above mentioned link to the manual along with a clear message "don't break it" so I'd rather ask twice than risk a dead RB .

Thanks again, both of you!