750UP resets if powered by 24VDC battery or ccontroller

Hardware MikroTik hardware general
1

Hello, we have been using the 750UP fairly successfully powering up with the factory supplied AC/DC power supply.
Even used up all 5 POE ports to energize ubnt or mikrotik radios very stable. Of course using good cabling for the POE and minding the calculations of length/loss.

We now are attempting to power the 750UP board with either a 24VDC battery bank, or via a charge controller, in both cases having measured voltage output of 24VDC.
Battery bank two 12V/100aH batteries in series = 24V
Charge controller, connected to battery bank = tested with meter, 24VDC 8Amp capacity…

the problem is that the 750UP constantly resets when we connect it either of these two ways:
it is not a STP cable/length issue as this is a lab test setup and we are using the very cable that came in the factory supplied power supply which we “trimmed” from the power supply, runs 1mtr. aprox.
The 750UP continues to work well off the power supply after the test setup so we make sure we are not testing with a unit damaged on or during the test.

We notice that the cable from factory power supply only has + and - so I can’t see what would be wrong with this setup as long as the source provides 12V with enough amps…

any suggestions would be appreciated.

2

I wonder if it has something to do with startup current ?

What happens if you only power up the RB750UP with no devices connected ?

Then add you devices one by one - is it still stable ?

Possible Workaround If so perhaps a startup script to disable E2-E5 immediately then at 1 second intervals enable each interface ?

3

please clarify at what case you have problem:

  1. RB750UP have problems powering other devices when powered form battery bank without charger connected

  2. RB750UP have problems powering other devices when powered from battery bank with charger connected

battery charges could have impulse power with lower frequency, and that could cause the problems. Current stabiliser could solve the issue (induction coil with capacitor)

4

SCampbell and Janisk, thanks for the replies.

Let me try to pinpoint and describe better.

  1. we have upgraded the firmware from 2.36 to 2.37 and it most be noted that this is step 1 for the 750UP to work properly, at least with the AC power supply. and we have had no problems at all with that scenario. 100% stable feeding poe to all 5 ports with devices connected to each port (up to the 2.5A @ 24VDC)
  2. We have a 24VDC battery bank, a TyconPower 2424 Charge controller which has 8A @24VDC output (not poe interface) feeding the 750UP (with 2.37 version), and we connect the controller to feed the 750UP via the cable cut from the power supply and plug into the DC in jack of the unit (so lab distance on that cable). Thus far we have not even attempted to connect devices to any of the 5 POE ports of the 750UP. And the unit just continuously resets.

Perhaps you can take another crack at this now that I have more correctly described the situation. I hope.

thanks,
XR

5

Guys, I am glad to report that the problem was solved by upgrading to version 2.38

all stable thus far.

thanks to all,