question

sam-carleton avatar image
sam-carleton asked

MPPT isn't putting out the current it could, why?

ve-luna.pngMy setup:

  • 95Ah Sealed Lead Acid battery
  • BeagleBoard Black running Venos OS
  • SmartShunt
  • Phoenix Inverter VE.Direct 800/12
  • MPPT 100/20
  • 4-75 watts panels for a total of 300 watts

When the battery is below 80% I will see the MPPT pulling in over 200 watts, but now it is stopping at 79 watts. If I put some load on the system, the MPPT will put out more power, but on these long sunny days often this little 95Ah battery only gets to 96% to 98%.

I am assuming I have something set wrong. Right now the MPPT has the following settings:

  • Battery: 12v
  • Max charging current: 20A
  • Charger enabled: true
  • Battery preset: user defined
  • Export Mode: off
  • Absorption voltage: 14.4v
  • Float voltage: 13.6v
  • Equalization voltage: 16.1v

Is there something I should be changing here, maybe in the SmartShunt or even in the Venos OS?


MPPT ControllersVenus OS
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2 Answers
wudwork avatar image
wudwork answered ·

I have a lot more solar and batteries and experience this exact same thing. A few days ago, we were moving to another campground and the sky was clear and sun was strong. I pulled over and put the trailer hot water heater onto electric and started driving again. With our phone connected to Cerbo website, we watched the (3) MPPT's bring down 1048 watts from our 1365 watt setup. We were very happy with this. As soon as water heated enough, and shutoff, the solar dropped back to 150 watts or so which is a little more than the loads in our trailer. Bottom line; I think the Cerbo/Venus has a brain that dictates how much each MPPT will output and controls that flow. I seem to recall a setting somewhere that dictates this, but not sure....

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seb71 avatar image
seb71 answered ·

The actual SOC might be higher than the one displayed.

What are your SmartShunt settings?

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sam-carleton avatar image sam-carleton commented ·

Here they are:


img-11dfb9936fb5-1.jpeg

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seb71 avatar image seb71 sam-carleton commented ·
The "Charged voltage" setting in SmartShunt seems too high for a lead-acid battery. In the SmartShunt manual, the recommended value for 12V lead-acid is 13.2V.


This is not the actual charging voltage of the battery.

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sam-carleton avatar image sam-carleton seb71 commented ·
Thank you, I have made the change and will see how it goes!
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