I just put together a full victron system for my motorhome that I’m having issues finalizing. I installed my Quattro II, Cerbo GX MK2, 3ea 300ah NG batteries, and lynx BMX NG with Distributors in a compartment inside the coach. I setup the compartment with some 12v Noctua fans to make sure I could cycle the climate controlled air through the compartment as needed. However, I can’t get the Cerbo to recognize ANY of the 4 temp sensor inputs. I tried the sensor that came with my Quattro inverter 1st and after I couldn’t get it to work I figured it might be a bad sensor. So, I ordered another victron sensor (#ASS000001000) which the cerbo manual says is compatible and it too failed to detect. Lastly, I bought some LM335’s from digikey and they don’t work either.
I have tried to update the cerbo firmware (3.53 currently installed), I’ve rebooted the system a number of times, have turned on and off all 4 temp switches in the cerbo. I’ve watched a number of videos online that walks thru the process so I don’t think I’m missing any steps. It seems like a fairly simple task to connect 2 wires, go into settings and turn on the analog IO’s for temp probes 1-4. My temperature devices do not show on the homescreen and there are no options for setting the relays via temperature control which I’m certain is because the cerbo doesn’t think sensors are connected.
So, what am I missing? I have measured all of the probes I have and while they have resistance that varies with temperature (holding it in my hand and via heat gun) they do not seem to put out any sort of voltage measurements. Do I just have the wrong sensors or is my cerbo just not working?
Sometimes the pins on the temperature probes are not long enough to reach the terminal connections on the GX device (though they are long enough to reach the multiplus terminal connections).
I have had this exactly situation before.
You can quickly tell because when you insert the temp probe connections into the GX terminal block it should not be possible to pull them back out again (with any reasonable amount of force). Instead you should only be able to remove them by pushing on the orange tab.
If you can remove them, they aren’t getting in far enough.
The quick work around is to remove the crimped ends, and just strip back the wire so that it’s long enough and insert that. You will need to twist the end, and ideally be careful with the insertion because it will be weaker. But it’s quite safe, there is no voltage on these connections it’s just reading resistance.
You can see here two identical model temperature probes supplied by Victron, one has a longer connection area than the other. Only one properly connects to the GX device.
I’m quite certain the wires are in all the way and I’ve switched all 3 probes around a dozen times with polarity back and forth, I get nothing that even registers in the Cerbo, it just doesn’t see them.
As for making sure they are switched on, as I said in the 1st post, I"ve switched all 4 on and off, rebooted, upgraded firmware, downgraded firmware, and then done it all again.
I’m using the classic UI for now, 1 thing at a time.
My biggest question is about the sensors - in my research I see many posts where people are getting voltage on the sensors but so far I haven’t been able to measure any voltage, just resistance. Am I supposed to have voltage? Hard to believe both victron sensors are wrong though.
I have tried from the remote console and the gx70 touch - from the device screen I go to settings, scroll down to IO’s, select analog, and scroll down to the 4 temperature inputs, select one and then touch again to move the slider over which highlights the selection. According to all the videos I’ve watched I should then be able to back out to the device screen and see a temperature which I don’t.
The original probe that I recieved with my Quattro ii did have shorter crimps on it which would not allow it to go in all the way, but it was quite obvious as it wouldn’t stay inside the terminal when I gently pulled it back. I cut the crimp off, stripped back about 5/8" of wire, and silver soldered the bare wires to make them stiff so they would slide into the terminal block easily.
With the wires installed in the terminal block, it is quite easy to remove the entire block and then back probe from the GX side of the block to make sure a solid connection is established. I have been trying to get this to work for the last 3 weeks, so I’m 100% confident it’s not a matter of wire insertion or forgetting to turn on the anolog inputs.
Guy Stewart - thank you for confirming the voltage/resistance question! That helps as it tells me all 3 probes are doing what they’re supposed to!
Wanted to make sure that I came back here to close the loop on this thread so others facing this same issue might have a resolution.
In the end, my Cerbo GX was malfunctioning and the temperature inputs were not working. I recieved the replacement today and all 4 of my probes registered on the first attemp. It took me 3 weeks to come to the “Bad Cerbo” conclusion however so I hope I can save others some time. The reason it took me 3 weeks is because I ordered a 2nd sensor because I didn’t trust the 1st one, and when that didn’t work, I then ordered some LM335Z’s to build my own sensors as others on this forum had said they should work as well. During that time I did a lot of research to make sure I wasn’t making a mistake setting it up, I wasn’t. It really IS very simple to set them up IF the cerbo is working.
This thread has some troubleshooting tips that helped me decide to replace the cerbo Temperature sensor on Cerbo. - VictronEnergy I couldn’t get my cerbo to register anything was plugged in and it wasn’t putting any voltage out on the terminal blocks. I spent some time on the phone with the tech support where I purchased the Cerbo and he also agreed my cerbo wasn’t acting like it should, so I went ahead and ordered a replacement and voila! It works.
On the orignal Cerbo, when I would interface using the Touch 70, there was a slow response like an old laggy computer. The new Cerbo responds to changes as fast as I can touch them, so that is an unexpected plus! At any rate, if you can’t get your temp sensors to work maybe this will help you.
For what it’s worth, all of my sensors I was able to measure resistance. I want to say it was like 35 or 35 kilo-ohms but I’m not in front of my meter at the moment. I would think that as long as you are using the sensor that comes with the inverter or the ASS000001000, you should be able to test if its working by simply checking resistance. As for the cerbo, that thread I linked had tips that included putting a resistor in place or shorting the positive and negative (I can’t say I recommend doing that so use your own judgement). At any rate, problem solved, thanks for the help!