Why is the online Temp Much higher than shown on the app?

[Timbloomfield]

Hi, I'm still learning new things about the system, as it's only three week old.
The app on my phone gives the battery temperature , and this seems to agree with the system's behaviour in terms of charging rate, low temp protection etc., The online webpage however, when I put select batTemperature from the drop down list, give me a graph that is completely different, and much higher,
Can anyone explain please?

Sorry, the numbers on the graph are a little blurred, but the temperature is up in the 20's.

[Dave Foster]

The batTemperature is the BMS temperature which is usually 6-10C higher than the temp you see in the V2 app.

What you are seeing in the V2 app is lowest cell temperature from all the batteries - that is much more useful as it is what the BMS bases it’s decision making on.

Sadly you can’t yet see that temperature in the website (or OpenAPI via Energy Stats or home assistant etc..) - We have asked for it to be added, and Fox have confirmed they will so just waiting on them to do the dev work for that.

[Timbloomfield]

Thanks, that explains it (although it just tells me it's not much use.) Can you explain "ambient temperature"? That also appears to be divorced from reality, peaking at 26 deg.

[Dave Foster]

Haha, yes ambient temp as you have guessed is not ambient temp, it is actually the internal temperature of the inverter, and whilst i’m here inverterTemp (invTemperation) is the temperature of the cooling fins on the back.

When the inverter is working hard you’ll see the InvTemperation go up a lot and the ambient temp will follow more slowly - in summer if InvTemperation goes above 50C the inverter will start to derate the solar output.