How accurate is system health voltage RB450 and GrooveA

RouterOS General
1

I have a remote (VSAT) installation with a solar powered RB450G running on 24V nominal DC solar power supply. It has two neighbors, both GrooveA-2hn powered also from the DC supply with POE, cable lengths are both 10m.

The max battery voltage can be 28.8V so we added a voltage regulator that holds the DC supply voltage down to 25V. Should be stable.

However, when I check remotely with winbox I see three different system voltages reported

Currently the 450G says 26.0V (and 59 deg C)
GrooveA - 1 says 24.3V
GrooveA - 2 says 23.2V

The DC power for these three is physically wired to the same output terminal of the voltage regulator and the two POE systems for the GrooveAs are identical (both 10m Ethernet cables). Thus the only difference should be a slightly less voltage in the GrooveAs due to cable losses. But the GrooveAs should be the same and they aren’t. Only difference is temperature - one is inside and one outside (tropical sun).

So can I conclude the sensor is not very accurate? If not why the big range?

2

What does your multimeter say?

Our’s compared to system health is very close.

3

The site is remote so I can’t use my meter just now. But my point is that all three are physically connected to the same DC power outlet. They have exactly the same input voltage. Only difference being the GrooveAs POE cable losses but the patch cables are the same length so they should be equal. But it is not!

4

Hi David,

don’t forget that voltage drop across a cable length always depends on current flow too - so if one of the groove devices is drawing more current than the other, voltage reading at the detection point will be different!

Cheers, Mike.

5

leeming the voltage sensors are not correct always +/- 1V maybe 2V

all my RB411AH are showing +1V more
Have RB750UP input 24V but it is showing 21.1V
Have Groove when its hot showing 2V less in night back to normal