question

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maxoffgrid asked

Absorption voltage set is not reflected in MPPT voltage reading.

System details:

  • EasySolar-II GX, 48v/3000VA
  • 2kw panels
  • 48V 100Ah (4 x 12v 100Ah GEL batteries)
  • No grid or generator connected.


Issue faced:

Absorption voltage set in smartSolar app is not reflected in the VRM mppt voltage reading. SOC reaches only up-to 70% max. This results in battery discharge up-to 50% at night time. I like to keep DOD as less possible to improve battery life.


Observation:

  • Battery preset used: Gel victron deep discharge(2)
    • Absorption voltage 57.6V
    • Float voltage 55.2V
  • Attached VRM plot below. absorption phase starts at 56.6v.
    • Though there is enough sunlight, not able to charge above 65% SOC.
    • MPPT reaches float mode when SOC is 60%.
  • 1663483299349.png


Question:

  • How can I set the Absorption voltage and float voltage to reach better SOC at day time?


Thank you in advance.

MPPT SmartSolarSOC
1663483299349.png (71.0 KiB)
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2 Answers
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pwfarnell answered ·

You are going to float with a current of 6A, do you have loads running whilst charging. If the absorption time was longer you.might get a bit more charge but it looks like you are getting close to full as the charge current is reducing. How are you measuring the SOC, from the Multiplus or do you have a shunt. Do you have any DC loads on the system. What are your settings for the shunt or battery in the Multiplus. Do you ever reach 100% SOC. I believe that this may be an error in your SOC, if you never get to 109% SOC to get a synchronisation the SOC errors accumulate.

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maxoffgrid answered ·
  • Yes, we do run the load while charging. Constant minimum load of 100watts is always there.
    • Attached AC output power details as well for reference below,

1663486424375.png


  • SOC reading are from Multiplus, don't have a shunt in current system. (Ordered a smart shunt better measurement of SOC)
    • Am not aware of battery setting in Multiplus, please help me set battery setting in Multiplus.
    • In SmartSolar app below preset has been set
      • Battery preset Gel victron deep discharge(2)
  • No DC load added to the system.
  • This week system has been configured as Hub-1. (Since we are fully off-grid)


Earlier, we were using different ESS based configuration.

  • In that we were able to reach 100% SOC
  • But the problem was mppt was always in bulk mode charging at 57.6V during sun hours.
  • Attached earlier graphs with ESS configuration below.

1663487114075.png


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1663487114075.png (56.1 KiB)
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