question

suavek avatar image
suavek asked

Battery temperature reading from a Multi's sensor in DVCC setup with STS turned on, while the Multi is switched off?

I've found out, that despite the Multi being switched off in this boat installation for most of the time (to conserve power), VRM reads the battery temperature from its sensor (see the first screenshot attached). Can the MPPT 75/15 being set up as DVCC with STS turned on, read the battery temperature sensor (while the Multi is switched off) in this installation?

In an older thread, I saw the answer that, the Multi should be in charger only mode at least to read the battery temperature, but still, some more clarification is needed as you can see the VRM reads temperature from the Multi's probe despite having it switched off.

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Venus OSVenus GX - VGX
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suavek avatar image suavek commented ·
Anyone can help me with this topic?
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1 Answer
klim8skeptic avatar image
klim8skeptic answered ·

You apparently have a Venus GX.

Move the multi's temp sensor over to the Venus GX temp port.

Re assign the STS to the Venus GX. Link.


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suavek avatar image suavek commented ·

It could work, although I use Venus to monitor the temperature in other compartments. I still need to know how is possible to see battery temperature from the Multi while it's switched off and whether it can be used by MPPT?

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klim8skeptic avatar image klim8skeptic ♦ suavek commented ·

I do know you should assign the sensor location under STS to your preferred device. You dont want the GX device to Automatic select a random cabin or fridge sensor.

temp-select.png

Settings > DVCC > Temp Sensor.

Did a test, turned off my multi and rebooted the Venus.

temp-select-1.png

Looks like when the multi is switched off (still powered tho) the temp sensor will not work.

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suavek avatar image suavek klim8skeptic ♦ commented ·

You are right, the Venus OS losts connection with the Multi when you reboot the Venus while the Multi is off, but then you can switch the Multi on, check its status, then turn it off again and check the status once more. You can see, that the Multi is off but the Venus OS reads the temperature from it.

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klim8skeptic avatar image klim8skeptic ♦ suavek commented ·

Ok, this is progressing nicely. 3 steps forward, 2 steps back. :)

Upon further investigation I can reveal not much. Some tinkering and modifications to my system shows this...

multiplus-temp2.png

Until 1:00pm my multi did not have a temp sensor fitted. What is shown above is that the multi passed on temp data derived from the battery sensor #23 fitted to the Venus. As what STS is supposed to achieve.

At 1:00 pm I added a temp sensor to the multi. At 1:10 pm I dunked that sensor into hot water. At 1:20pm I changed the STS sensor location over to the #261 multi. At 1:30pm the VRM showed that the #261 sensor was warm, and the #23 sensor was at batt temp. At 1:35pm I switched of my inverter via the rocker switch.

An hour later revealed that the multi temp sensor went off line. The #261 output voltage and current plot showed an hour output gap. #23 temp sensor was fine. #261 VE bus state seems to have missed the hour of being switched off??

@Suavek please confirm what temp sensor has been STS linked to via remote console.

@Suavek please check that the sensor reacts when being warmed up.

@Suavek please confirm that VRM looses contact with the multiplus temp sensor when the multi is disconnected from the battery.

Firmware Venus v490, Multi v2.85.

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