Short circuiting my solar controller

AmyPAmyP Registered Users Posts: 2
Hello,
     So I'm using 20 W solar panel to charge a 6 V 7 Amp battery. I've got a Y-SOLAR IP67 controller paired with a LM2596 Dc-DC Buck Converter Step Down Module power supply. to help regulate the power. Any chance someone knows why this "system" would be short circuiting? Please excuse my ignorance if the answer is obvious or impossible to know. I appreciate any input or suggestions.
~Amy



Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,684 admin
    Welcome to the forum Amy.

    You do have several issues here... You can post a link to your solar charger (so we can see the specifications). Also, it would be nice to see a link for your panel too.

    You might want to look for a 6 volt capable charge controller. That would limit the need for the DC to DC converter:

    https://www.amazon.com/Controller-Waterproof-Lead-acid-Charging-Discharging/dp/B00XTQ76WW

    DC to DC converters are not usually a "good fit" for solar charging. Depending on how deep you want to get into the Electronic Engineering discussion--The typical DC to DC converter "cares" about the DC output (voltage and current set points). They just assume they are connected to a battery that is ~10-30 VDC (or whatever yours is rated for).

    https://www.amazon.com/LM2596-Converter-Module-Supply-1-23V-30V/dp/B008BHBEE0 (typical LM2596C buck converter)

    Solar panels themselves are not really "solar batteries"--They are current sources (more or less, current = amount of sunlight hitting panel, and solar panel voltage may vary from zero volts to ~20 Volts (typical 12 volt panel).

    The solar charge controller itself is not a "regulator" in the sense you are familiar--They are PWM type controllers--Pulse Width Modulated--Basically an "on/off" switch. The switch may be on 100% of the time (full current), or 50% of the time (on for 1/2 second, off for 1/2 second), or mostly off (1/100 second on 99/100 seconds off). More or less like "dimming your lights" by rapidly turning the light switch on/off.

    The DC to DC converters typically do not like this type of input power being "chopped" (if you are connecting the output of the charge controller to the input of the DC buck converter, and output to the battery bank)...

    You may also have a 6 volt Y-Solar charge controller (I could not find one with a quick search). If you do have a 6 volt solar charge controller, then I want to confirm you are connected as follows:

    Solar panels ==> Y-Solar Charger @ 6 volts ===> 6 Volt Battery
                                                                             []=> On/Off switch ==> DC to DC converter ==> Regulated voltage for DC load(s)

    If, for example you are connected like this:

    Solar panels ==> Y-Solar Charger @ 12 volts ==> DC converter ==> 6 volt battery bank ==> DC loads

    Or other combination--That gets confusing and does not play well together.

    Also, want to know "what is short circuiting"--What is happening?

    And--Just to make sure everything is done correctly... Your 6 volt battery needs to be around 6-7 volts. And, always connect the battery to the solar charge controller first, then connect the solar panel(s) second (and disconnect panels first, then battery bank second).

    If you connect solar panel (under sun) to the solar charge controller first, in may confuse the solar charge controller (bad boot, may "pick" the wrong battery bus/charging voltage/etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AmyPAmyP Registered Users Posts: 2
    Hi Bill,
        
    Thank you so much for your thoughtful reply!! I started down the road of a step down DC-DC buck board because I bought the unit 6-12V solar controller unit you linked in your reply.


    The solar panel:

    When the units arrived the spec indicated 12V 5A. Thinking it might work anyway I used them but found they had stopped working overnight and were blinking rapidly indicating a short circuit from the load light.
        
    I am going to attempt to tell you how things are connected...connected like this:
    Solar panel ==> Y-Solar Controller <== Battery
    Y-Solar Controller (load) ==> DC-DC Converter (-) Lead == (-) Lead of DC load
                                                  DC-DC Converter (+) Lead == (+) Lead of on/off switch
                                                  (+) Lead of DC load == (-) Lead of on/off switch

    In year's past I've used the same connection with a 12 V motor/battery combo. Perhaps I'm recalling the order of connection incorrectly...

    Great points on the order of connection to the solar controller. I wasn't aware of the why of the solar panel connection part.
    ~Amy





  • BB.BB. Super Moderators, Administrators Posts: 31,684 admin
    edited April 19 #4
    OK... Start with the basics. First connect the controller to the battery. And second connect the controller to the solar panel (in sun
    Solar panel ==> Y-Solar Controller <== Battery

    Measure the input voltage from the solar panel, and the output voltage to the battery bank. Want to make sure that the solar charging is OK.

    I hope you have a voltmeter?

    The Load terminal is "open"... LED should indicate normal operation (LED on solid).

    The controller and solar panel look fine for your needs... Technically, the Vmp~17.5 volt solar panel is higher voltage than the PWM solar charger + 6 volt battery can efficiently use... Basically, you can only get around:
    • 1.14 Amps Imp * 7.1 volts battery charging = 8.1 Watts from solar panel to battery bank in full noontime sun panel pointing at sun.
    It is just the nature of the PWM controller and the solar+battery specifications.

    Watch Solar Panel and Battery polarity to the charge controller (positive to RED; negative to BLACK leads). It is easy to fry the components if connected backwards.

    How do things look so far?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 31,684 admin
    edited April 19 #5
    Also, I am expecting you are placing only small loads on the battery/buck converter... Like 1/2 amp to 1.x amps maximum for relativley short periods of time (you have ~3.5 AH of "useful energy" from the battery (50% discharge for longer life)... A 1/2 amp load would:
    • 3.5 Amp*Hour draw from full battery  / 0.5 Amp load = 7 hours of discharge to 50% battery capacity
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 5,576 ✭✭✭✭✭
    Sounds to me that they didn't send you a 6 volt charge controller, Which, I think, is what Bill is checking out.

    You said;
    AmyP said:
    When the units arrived the spec indicated 12V 5A. Thinking it might work anyway I used them but found they had stopped working overnight and were blinking rapidly indicating a short circuit from the load light.
    So I think it doesn't say;

    It now says rated for 12V, with no mention of 6volt?

    I think you just have a charge controller doing it's job, with the battery voltage so low it's 'out of gambit' with the controllers ability to charge.

    Y-Solar is an okay company which makes a lot of inexpensive charge controllers for others. Their English web site has been down for a while, but I use to go there to find manuals for some 3rd party charge controllers. I helped a guy get setup with a minimal charge controller/inverter for a 48 volt setup and his has been running fine for 3+ years now.

    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 backup...lol), 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.
Sign In or Register to comment.