Question

Hello,

I have the RUT955 connected to a 24 volt system. I want to use pin 6 & 9 to measure the voltage of the system. However, I noticed in the wiki that the maximum voltage is 24 volt: https://wiki.teltonika-networks.com/view/RUT955_Input/Output#Status

Since my system is solar powered 24 volt, the voltage is normally between 25 volt at night and 28 volt during the day. Is this voltage too high for the RUT955 pin 6 & 9 to measure?

What happens if voltage exceeding 24 volt is fed to pin 6 & 9, can the router be damaged? The absolute maximum voltage is 30 volts during battery equalization.

Please let me know so that I don't fry this wonderful device.

Answer 1

Hello,

In fact, the RUT955 analog input supports voltages higher than 24V, but a safe long-term input voltage can be up to 24V.

But here a so-called voltage divider can help you.

More on this was discussed here:

Analog-input-voltage-scaling

Basically, you need to connect a 100K ohm resistor in parallel. This will reduce the output voltage by 50%, which is the safe Analog voltage input value and will not damage the router.

Regards.

Comments

Hello,

Thank you for your answer. Noted on the voltage divider for the analog input, I will investigate this.

Do you recommend to also use a voltage divider for the power input of the device? The device is functional between 9 and 30 volt. My system is connected to a 24 volt battery system (two 12 volt batteries connected in series). The system never exceeds ~28 volts during peak charging handled by an MPPT controller. It is a DC system so there are no voltage spikes higher than 28.

Can this voltage damage the device long-term? I saw a warning about this here: https://wiki.teltonika-networks.com/view/RUT955_Powering_Options

If you decide not to use the standard 9 VDC wall adapter and want to power the device from a higher voltage (15-30 VDC), please make sure that you choose a power supply of high quality. Some power supplies can produce voltage peaks significantly higher than the declared output voltage, especially during connection and disconnection.

While the device is designed to accept input voltage of up to 30 VDC peaks, high voltage power supplies can harm the device. If you want to use high voltage power supplies it is recommended to also use additional safety equipment to suppress voltage peaks from the power supply.

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The specified warning for power supply is correct.

Hence, power input voltage up to 30V is safe. If there are no voltage peaks, you do not need to take any further action.