Epever 40 ah controller and 3 x numax 105ah battery settings

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• MichaelK Registered Users Posts: 233 ✭✭✭

  March 2022 edited March 2022 #2

  There is little here to go on?  What question are you trying to ask, what charging parameters to program?  What's the brand of batteries?  How much solar do you have?  Number of panels, Vmp, Voc, ect?
  

  
  

  Looking at a comparable Trojan battery, I could say set an Absorptive voltage of 14.7V, Floating voltage at 13.5V, and equilization at 16.2V.  For trial and error, you might want to start the max charging voltage to 14.4, and work your way up to 14.8?

  
  

  An important missing parameter here is how many amps you can charge at?  These are three 12V batteries wired in parallel?  Assuming you want a max charge rate of 1/8C that works out to be (105Ah + 105Ah + 105Ah)/8 = 39.4A, which is right the limit of your controller.

  
  

  Bulk charging is going to start at around 12.5V to 13.0V, so to get 39.4 at that voltage you need 39.4A X 13Vcharging = 512V of panels.  Considering that panels almost never put out their rated output, I always include at least an 85% fudgefactor to compensate for lower output, so that works out to be 512W/85% = 602W of panels.

  
  

  You could meet this 602W goal in a number of ways.  You need to remember though that your controller has a 100V limit that must not be exceeded ever, or it will go poof!  If you took six 100W panels, with a Vmp of ~18, you can NOT wire them in series.  18V X 6 panels = 108V  You could wire them in a 3S2P configuration.  That is two parallel strings of three panels in series.  That would feed ~11A at 54V into the controller.

  
  

  A different option and maybe for cost effective is to go with higher voltage grid-tie panels.  Two 72-cell 300W panels with a Voc of ~42V would be 84V wired in series.  Keep in mind that solar voltage goes up as the temperature outside goes down.  So, two panels that put out 84V at room temp might put out 94+V at freezing temperatures.
  

  System 1) 15 Renogy 300w + 4 250W Astronergy panels,  Midnight 200 CC, 8 Trojan L16 bat., Schneider XW6848 NA inverter, AC-Delco 6000w gen.

  System 2) 8 YingLi 250W panels, Midnight 200CC, three 8V Rolls batteries, Schneider Conext 4024 inverter (workshop)
  

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• rm82 Registered Users Posts: 2 ✭

  March 2022 #3

  thank you very much for your response
  
  unfortunately I couldn't find much out regarding the batteries
  
  i have two 295w solar panels which i am going to mount to my van roof
  
  they have a
  
  Vmpp of 30.93
  Impp(a) 9.54
  VOC 37.18
  ISC 10.08
  panel efficiency 20.07 %
  
  I am in the UK so not to sure what settings to use, for what I actually have and I am new to solar
  
  thank you very much
  
  

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• BB. Super Moderators, Administrators Posts: 33,268 admin

  March 2022 #4

  Generally, with Sealed batteries, you want to keep the charging voltage down... Probably closer to 14.2 to 14.4 volts for Absorb (charging) set point.
  
  And there are variations in sealed batteries. There are flooded cell type with "sealed caps" (and pressure relief valve--for all types of sealed batteries)--Where you can monitor electrolyte levels and add distilled water if/when needed.
  
  And there are GEL and AGM (absorb glass mate) type batteries. These batteries, you cannot add distilled water too--If they vent from too high of charging voltage, then they will vent gas hydrogen+oxygen (and possibly electrolyte) and lose water (the batteries should recombine H+O back into water). Too high of charging voltage, and the amount of gas generated will be too high for the battery to manage (vent gases, overheat catalyst if present, etc.).
  
  For float--13.5 volts is probably fine. And for EQ (equalize charging), either set No EQ charging, or set EQ voltage to charging voltage of 14.2 to 14.4 volts. For generic sealed batteries, EQ charging is either not done--Or only performed every (roughly) 6 months with EQ voltage set to Absorb voltage, and held for 8 hours or so. Full voltage EQ is "controlled over charging" to bring up "weak cells"--GEL and AGM (a type of lead acid battery) is never a good idea. For flooded cell Lead Acid batteries, you can add distilled water every 1-6 months to make up for water lost during elevated voltage EQ.
  
  You never want the batteries to vent (as they age and get near failure--They can and probably will vent--So you still need the "battery box" to have ventilation to prevent buildup of Hydrogen gas and possibly electrolyte mist). If you hear your batteries venting, or they are getting too hot--Back down on charging voltage.
  
  -Bill

  Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  

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