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MikroTik App
 
RobWX1N
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Joined: Thu Nov 28, 2019 4:02 am

Voltage accuracy - are any models better?

Tue Jan 11, 2022 11:20 pm

Good afternoon,

We have a number of solar-powered sites with limited voltage monitoring. Since an outage can mean a decent hike carrying a generator, it's nice to be able to monitor and plan in advance. However, adding an additional piece of equipment to do so isn't viable due to the increased power consumption. About a year ago, we decided to use MikroTiks in place of switches, for their voltage monitoring capability. While it has helped some, we've discovered that the MikroTik voltage readings are less than accurate on most of the units we're using - around 0.4 to 1.0 volts off, and not always off by the same amount, which makes accounting for the inaccuracy a little difficult. After doing some reading, I see this is a common issue, with a lot of posts from 10+ years ago. I am hoping that maybe someone could help answer some of the following questions.

-Are there any models known to have more accurate voltage measurement than others? If so, which ones?

-We are still trying to figure out whether the difference in offset from time to time on a given unit is related to it's specific voltage at that time, or if it is temperature related, or if it is just a factor of the lack of true resolution of the measurement. The time of year and remoteness of the sites has made it difficult for us to make much progress in determining this, so if anyone has experience trying to narrow down the calculation of the true voltage from the MikroTik reported voltage, could you share your findings?

Thank you,

Rob
 
mada3k
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Joined: Mon Jul 13, 2015 10:53 am
Location: Sweden

Re: Voltage accuracy - are any models better?

Thu Jan 13, 2022 12:10 am

My guess is that they are probably using a simple voltage-divider, and resistors has a certain tolerance (like 5-10%) and that will vary with temperature as well. I would probably take a measurement with a good voltmeter on each individual device, and note the offset from the self-reported value (this can then be corrected in your monitor solution).

But even if you only have 1 volt of precision, i's no problem to tell if a regular SLA battery is not charging or getting low.

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