Solar CHarge Controller Question- shows fully charge when not.

mannj24mannj24 Registered Users Posts: 1

I have purchased 2 solar charge controllers on Amazon- and both have failed. I have 3, 100 watt panels wired at 12 volts. And I have 3 100AH AGM batteries. 

The last charge controller I bought - kept showing my batteries as fully charged, green light and stopped charging- however the battery bank was at 11.9 volts-- fully charge should be near 13 volts. So I bought another 30AMP solar charge controlerr- followed directions and when I connect the battery it shows FULL 100% CHARGE.. I check my battery with my meter- and seperate elec gauge and both show 11.9.

Any ideas? I am a newby at this- but it is a simple hookup- every charge controller I try- shows my batteries at FULL charge and stops charging, but when I check with a meter- the batteries are near dead at 11.9.


  • PhotowhitPhotowhit Solar Expert Posts: 5,182 ✭✭✭✭
    Are your solar panels hooked up and it's indicating fully charged?

    Inexpensive charge controller can only have a voltage based reading of State of Charge. While charging the voltage is likely above the voltage representing fully charged (12.7 volts). Just ignore the light. If you have a meter you can measure the voltage with the solar panels connected and without and see the difference.

    ...someone made the brilliant statement that to fix the charge controller, just put a piece of tape over the light that indicates fully charged!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do
  • mcgivormcgivor Solar Expert Posts: 3,405 ✭✭✭✭✭
    With automatic voltage detection always hook the battery first, then solar. Are there any setting menus, you might have to set these to your particular battery type, it may have a low default to prevent damage as not all battery voltage requirements are the sams, just some thoughts.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • littleharbor2littleharbor2 Solar Expert Posts: 1,517 ✭✭✭✭
    Are your batteries New?, Old?, Toast?

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

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