Solar controller

sparky1958 Registered Users Posts: 1
I'm trying to understand why my solar controller is putting out 22v  to charge my 12v Battery. I have a 30w panel I read 22v at the panel and that is what is going into the controller. The same voltage is coming out going to the battery when it says cut out is 14.2v and cut in is below 12. Should i not be getting 14.2 volts going to the battery, I don't want to over charge it or blow the battery.


  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    What is your controller model, and what is your battery ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    gen: ,

  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    How are you measuring the 22 volts output? If you disconnected the battery to measure, then perhaps you are measuring the short circuit voltage from your array.

    Along with Mike's questions did you hook up the battery first and then the charge controller?

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former, 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • NANOcontrol
    NANOcontrol Registered Users Posts: 261 ✭✭✭
    That would have to be a pretty sulfated battery to do that. Could this have been going on for a long time?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    Solar charge controllers are not really "voltage regulators". The "simple" type are PWM converters---They are just an electronic "on/off" switch. On, solar panel is connected to battery bank. Off, solar panel is disconnected.

    Your solar panel will run from zero volts (night) to ~22 volts (Voc--Voltage open circuit). And solar panels are (for the most part) constant current devices... I.e., when the panel is under full noon-time sun, the panel will output ~Imp (current maximum power). 

    In reality, your battery is the voltage regulator for the system. The charge controller just regulates the average current required to charge and keep the battery at the correct average voltage.

    If you try to run the solar charge controller without a large lead acid battery connected, you will see weird results (most solar charge controllers draw their "working voltage" and basic charging voltage 12/24/48 volts from the battery itself--Not from the solar panel--And if connected to the solar panel only, the controller may boot up funny or even damage the charge controller).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    If everything is connected properly and in the proper sequence than there's no way the controller can put 22 volts into your battery because your battery will clamp the voltage down to something like or slightly higher than the actual battery voltage, which for a 12 volt battery 22 volts is pretty much impossible.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.