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methodvans avatar image
methodvans asked

Cerbo GX temperature relay to start up a cooling fan

I'm looking to use the Cerbo GX to activate a blower fan in an electrical assembly box at a certain temperature and stop once a differential temperature has been achieved. The blower fan is 12VDC and draws only 10 watts. I would incorporate a VE temperature sensor in the temp sensor port.


I'm looking for detail how to make all the connections and do the programming to achieve this. The programming seems somewhat self explanatory from the manual, but I'd like to confirm plus confirm the physical wiring that needs to take place.

cerbo gxTemperature SensorRelay
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4 Answers
wkirby avatar image
wkirby answered ·

It is possible to connect a low power fan as you suggest using the relay contact directly. The Cerbo GX relay is just a dry contact so the power for your fan will need to come from somewhere else and the relay wired like a normal switch to the fan. Use the COM and NO relay terminals.
The temperature sensor should be connected to one of the Temp inputs of the Cerbo GX.
Use one of there type of sensors: https://www.victronenergy.com/accessories/temperature-sensor-qua-pmp-venus-gx

Programming is done via the menus. Choose the relay you are using from Setting -> Relay and then set up the Function as Temperature:
1644036803152.png

Then go in to the "Temperature Control Rules" and choose the Temperature sensor you want and set up your conditions for activate and de-activate:
1644037030887.png



1644036803152.png (12.2 KiB)
1644037030887.png (24.2 KiB)
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Michel Levesque avatar image Michel Levesque commented ·

Hi. I am trying to do exactly the same thing. I have a Cerbo GX with the (EDIT: NOT the) latest firmware, and the proper temperature sensor connected to temp port 1 of the cerbo. I activated the analog IO setting so the temp sensor output 1 is also shown on my main screen, displaying the proper temperature.

But when getting into setting>relay menu, the option to pick temperature sensor function is not available. I tried to connect the temp sensor on my multiplus, but same problem. I rebooted the device, not working either.

Any reason why I cannot see the temperature sensor function in the relay activation menu?


EDIT: After review and support from an other post, the problem is my Cerbo GX was on firmware v2.73. the temperature controlled relay is a feature appearing on the firmware v2.9. A simple firmware update resolved my issue!

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wjf avatar image wjf commented ·
@WKirby Are you able to help. We have a managed 48V battery, and when it gets to a low temperature it buttons off the charge rate. We want to set up a heater to heat the room, and power this only from excess solar. For example, at 5 degrees it allows 10A of charge per 100Ah of battery. On a frosty morning we could be making 100A. We want to be able to switch a relay on based of temperature (that bit is easy) but then also based off when the PV is over 50A.... Is that possible?? Any other clever ways to do this??
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sweyn avatar image sweyn commented ·

Hi, could anyone please expand on this part of the answer?

“The Cerbo GX relay is just a dry contact so the power for your fan will need to come from somewhere else and the relay wired like a normal switch to the fan.”

Anyone got a picture?

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t3z-gb avatar image t3z-gb sweyn commented ·
I need this to, have you managed to work it out?
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sweyn avatar image sweyn t3z-gb commented ·
I have not done it yet, but I believe yes you can just use it as a switch and run 12V through it to the fan. Not sure what the maw wattage is through.
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t3z-gb avatar image t3z-gb sweyn commented ·
Thank you. Will give it a try with a single pc fan.
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markhandley avatar image markhandley t3z-gb commented ·

As per manual

1658438510539.png

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1658438510539.png (150.0 KiB)
kevgermany avatar image kevgermany ♦♦ sweyn commented ·
Late reply, but for clarity, it means the relay does not provide power, it's simply a switch.
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markhandley avatar image
markhandley answered ·
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waninae39 avatar image
waninae39 answered ·

This is s good article on how to control devices like a fan. i don't want my Mutiplus to get too hot

but i don't want to have to run a fan all the time.

The Ruuvi devices can be controlled via BT from your cerbo GX

https://www.vanlifeoutfitters.com/using-a-ruuvitag-to-trigger-a-cooling-fan-in-your-electrical-system-with-a-victron-cerbo-gx/

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markhandley avatar image
markhandley answered ·
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Related Resources

Cerbo GX product page

GX family product range

Cerbo GX & GX Touch datasheet

Cerbo GX Manual

Venus root access document

Victron temperature sensor disambiguation table - which product supports which sensor


Additional resources still need to be added for this topic