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David avatar image
David asked

Multiplus doesn't see Cerbo GX Temp Sensor

I have a Multiplus (Easyplus) 12/1600 along with a Cerbo GX and other stuff.

Because I want to use the BMS Assistant on the MP, I had to use the Temperature Sensor input for the control signal (the MP 12/1600 has no other Aux input). This works well and I can control the Charging feature exactly as I want with this assistant.

I was fine with doing that as I could use a Temp Sensor that was connected to the Cerbo GX instead and enable DVCC and the STS feature. That seems to work fine for the SmartSolar MPPT and that picks up the temperature from the sensor correctly, but the MP shows the temp reading as either "NaN C" or "20 C".
I have two temp sensors on the GX and I have tried setting the Sensor in the STS selection to either one of them and it makes no difference to the MP - although the MPPT sees the change (and neither are 20 C either).

Any ideas why the MP is not picking up the Temp Sensor data from the Cerbo GX?

Multiplus-IIcerbo gxDVCC
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3 Answers
Mark avatar image
Mark answered ·

I agree that something seems off here with DVCC-STS and the MultiPlus - could you please confirm what FW revision your running in the MultiPlus?

Also try to reboot the Cerbo in case you haven't already after making the recent DVCC and temperature sensor changes.

On the other topic of the 2 wire BMS assistant, I can confirm that even if you have no Lithium battery settings programmed, as soon as you load that assistant it automatically disables temperature compensation (despite it being set) and forces absorption stage length in the background. Unfortunatly this behaviour is not documented and it generally makes that assistant unsuitable to use as a means to manually enable/disable the MultiPlus inverter or charger with non-Lithium batteries.

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David avatar image David commented ·




Firmware is 430. This MP came directly from Victron Netherlands less than a month go so I assumed (bad I know!) that it was up to date and didn't check for any updates.
Rebooting makes no difference.

Interesting comment on when you load that assistant it disables Temp Compensation. If that is the case, then it all makes sense.... MP fixes the temp at 20C with no varience which will in effect disable the compensation even though it might be programmatically still in place. (I have not seen that settable in VE.Configure though, so have assumed there was a default value in place for non -Lithium batteries)

However ... I removed the assistant in VE.Configure, uploaded the new file, reset the MP and I still don't see a temperature showing (apart from the 20C mentioned), so I have my doubts if the Multiplus actually supports DVCC Temperature Data IN, but just OUT (on my MP 12/3000 setup, I was using the MP Temp Sensor to send to a 100/30 MPPT no problem via DVCC).

It is rather disappointing that there is no simple way to just enable/set Passthru in the same way that you can have the other functions (On, Off, Charger Only, Inverter Only).
I suppose I will have to reconnect the Temp Sensor to the MP directly as I don't see any other way to have the battery temp known by the Multiplus, but this is something I think needs to be fixed by Victron.



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Mark avatar image Mark ♦♦ David commented ·

Since you have a MK3 to USB interface I recommend to update the MultiPlus FW to the latest release (currently FW v476 is the latest) as a first step if you are comfortable to do it yourself, otherwise contact your dealer. FW v430 is quite old now and from before STS was able to provide temperature data from the Venus device (although I didn't think the MultiPlus FW changed for this, it may have).

There was also a fix in Venus FW V2.60 for this very issue (see the change log on Victron Professional), I assume that you are already running V2.60 in the Cerbo?

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

What batteries do you have?

The MultiPlus (and the MPPT) only needs the temperature to make the temperature compensation during charging, but with lithium batteries you shouldn't use temperature compensation.

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David avatar image David commented ·

You may not need to use Temp Compensation with Lithium, but you do need to stop the charger below around 5C (just a note to accompany the comment about Lithium).

Anyway, that is a digression - I actually have Lead-Carbon batteries (these specific batteries recommend compensation of -4mV/C/Cell) so I do really want to have the Multiplus know the battery temp.

I am using the BMS Assistant not because I have Lithium, but I want to be able to turn the Charger off and have it work in Passthru mode sometimes (for my own reasons).

It doesn't change the point and problem that the Multiplus is not seeing the Temperature Sensor correctly - unless you are thinking the BMS Assistant disables the Temp Sensor function?


Update: That last point made me wonder if within the programming there was an assumption that if using the BMS Assistant you must be using Lithium - and so a Battery Temp reading was unimportant so not brought in? So I just ran VE.Configure, removed the Assistant and reloaded ... no difference. Still no Temp Data (or rather either no temp, or 20 C again)

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David avatar image
David answered ·

No ideas about why this is not working as it should?


Below is a bit of a combo screenshot showing:

The VRM data for MP (ID #276) (at this moment, the MP (#276) is showing 20C rather than the alternative "NaN C");
The selected temp input on input 4 on the Cerbo GX (ID #27);
A shot of the Control Panel showing what is selected and enabled within DVCC;
The settings for the MPPT via Victron Connect, showing the temperature of 13C, confirming it is picking up the Temp Sensor through the DVCC service ok and so that aspect is setup ok.

ep1600-tempissue.png



ep1600-tempissue.png (230.0 KiB)
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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

Hi @Wildebus,

The 20°C in the VE.Bus Summary seems to show MultiPlus internal temperature. Mislabeled I think. It's the same for me.

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David avatar image David Stefanie (Victron Energy Staff) ♦♦ commented ·

Thanks for reply.

I am not sure if that 20C is actually anything - I am saying this as that value, unless it is "NaN C" is ALWAYS 20C - it never varies even by a degree. The MP temp must change when the charger is in use, or the inverter is running, but this number displayed never changes.

(it used to when I initially installed it before I repurposed the "Temp Sensor" input for the BMA Assistant). This is a new install, BTW. Less than a week old.

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