Enter Zipcode

Results 1 to 9 of 9

Thread: Charge Controller - reverse polarity???

  1. #1
    Junior Member
    Join Date
    Aug 2013
    Posts
    3

    Default Charge Controller - reverse polarity???

    Hi, new to forum, thanks for all the great info. I have a problem with a simple 12 v solar system in my boat... a 12w panel, going to a morningstar/sunguard SG-4 charge controller, going to a fuse on the positive controller output, and then to a deep cycle marine battery. I use it to keep that battery topped off. The problem is... when I test output from the charge controller, I get nothing, not even the "negative voltage" you see when polarity is reversed. But, if I switch the panel output polarity (going into the controller), I get correct voltage if i also switch polarity on the output of the controller as well. BTW the panel tests fine without the controller, and polarity is normal, exactly as indicated on the panel itself.

    Before I replace the controller, I have a few questions:
    Do you think the controller was wired backwards at the factory? Is it possible that the polarity reversed when the contorller failed? I've never heard of that.
    Is it OK to put a load on the battery while the panel/controller is connected, for starting the boat? I've read different views on this.
    Is it OK to switch the battery switch while the panel/controller is connected? (the solar system is hardwired to the deep cycle battery, but that battery and another battery are connected to a standard switch... 1 -2 - Both).
    Any suggestions for a simple charge controller to keep the battery topped off? I definitely want a floating charge, and PW to keep the lead acid deep cycle battery in good shape.

    Some background:
    I'd wired everything correctly, checking resistance on the wire runs (15' from panel to charge controller using 16 guage wire) to ensure I was maintaining polarity, and installed in my boat. I couldn't really test the output from the charge controller when I installed it in the boat last spring (total shade), but it's pretty darn simple so i figured it would just... work. Never really knew for sure if it was keeping my battery topped off, until last weekend the battery was completely dead. That's when I ran the tests. I've always covered the panel when connecting/disconnecting.

    Any help will be appreciated!

  2. #2
    Solar Fanatic
    Join Date
    Feb 2010
    Posts
    12,713

    Default

    If it was wired correctly in the proper order to start with, you would have had a voltage on the output of the controller period. That voltage would have came from the battery, not the controller. Th ebattery is the ver first thing to be terminated to the controller, then the panels are last. So if you do not see battery voltage on the output of the controller you have a wiring error.
    MSEE, PE

  3. #3
    Junior Member
    Join Date
    Aug 2013
    Posts
    3

    Default

    Quote Originally Posted by Sunking View Post
    If it was wired correctly in the proper order to start with, you would have had a voltage on the output of the controller period. That voltage would have came from the battery, not the controller. Th ebattery is the ver first thing to be terminated to the controller, then the panels are last. So if you do not see battery voltage on the output of the controller you have a wiring error.
    Thanks for the reply. i did wire it in the correct order, to battery first, etc. But I guess I'm missing something in your reply... if it's connected to the battery, and the battery is already charged, how do i know if the controller is working? I'm guessing that you mean by testing the output of the panel and controller, while not connected to the battery, will show no output? That's what I'm seeing, unless I reverse polairty as described. Thanks!

  4. #4
    Solar Fanatic
    Join Date
    Oct 2012
    Location
    Clearwater Florida
    Posts
    2,955

    Default

    Quote Originally Posted by twaw001 View Post
    Thanks for the reply. i did wire it in the correct order, to battery first, etc. But I guess I'm missing something in your reply... if it's connected to the battery, and the battery is already charged, how do i know if the controller is working? I'm guessing that you mean by testing the output of the panel and controller, while not connected to the battery, will show no output? That's what I'm seeing, unless I reverse polairty as described. Thanks!
    The controller will not show an output if it is not connected to a battery.

    Use the battery a little so it is not fully charged. Then connect the battery first and then the solar panel to the controller. While the sun is shining on the panel measure the input voltage to the controller. This should prove the panel is working.

    Next measure the output voltage of the controller. If the solar panel is generating and the battery is not fully charged you should see a voltage reading above 13 VDC. If you are only seeing about 12.5 VDC or battery voltage then the controller is either not working or not wired correctly.

  5. #5
    Solar Fanatic
    Join Date
    Feb 2010
    Posts
    12,713

    Default

    If you disconnect the battery, and leave the panel connected with sun shinning on the panels, you will let the magic smoke out of the controller. The controller gets it power from the battery, not the panels.

    It is real simple to tel if the battery is getting a charge by just monitoring the voltage of the battery even if it is fully charged and in float mode. The controller will even tell you with indicator lights.
    MSEE, PE

  6. #6
    Solar Fanatic
    Join Date
    May 2012
    Location
    Placerville, CA. In the Sierra Foothills, around 2000 ft. altitude, occasional snow.
    Posts
    5,239

    Default

    Quote Originally Posted by Sunking View Post
    If you disconnect the battery, and leave the panel connected with sun shinning on the panels, you will let the magic smoke out of the controller. The controller gets it power from the battery, not the panels.

    It is real simple to tel if the battery is getting a charge by just monitoring the voltage of the battery even if it is fully charged and in float mode. The controller will even tell you with indicator lights.
    One thing to be on the lookout for is miswired/mismarked interconnecting cables.
    Some unfortunate posters have described getting interconnecting cable sets from Horrible Fright (Harbor Freight) whose plus and minus terminals were wired to the MC4 connectors in exactly the opposite way all other are.

    The result was that if you used their cables with their panels everything worked fine, but if you used those cables anywhere else you got a polarity reversal.

    My best guess is that you either are not reading the polarity markings correctly or have a polarity reversal in the wiring on both sides of the CC. Please check it out with a voltmeter before you spend too much more time trying to figure it out without the right tools.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

  7. #7
    Solar Fanatic
    Join Date
    Jul 2012
    Location
    Southern California
    Posts
    870

    Default

    Quote Originally Posted by twaw001 View Post
    Hi, new to forum, thanks for all the great info. I have a problem with a simple 12 v solar system in my boat... a 12w panel, going to a morningstar/sunguard SG-4 charge controller, going to a fuse on the positive controller output, and then to a deep cycle marine battery. I use it to keep that battery topped off.
    The other issues have been adressed so...

    A 12W panel / cc to a deep cycle battery is more of a maintainer, and not a top-off really. Especially if your panel is horizontal on the boat, and your solar-insolation is poor in the marina. A maintainer will just help offset self-discharge and light parasitic draws and essentially try to keep the battery in the state is was found in, and not really top-off aside from a superficial surface-charge. Given that this is solar, that is only doing it's job about 4 hours a day at best depending on where you sail / moor, so not much is happening. Horizontally mounted, this would be a pipsqueak.

    Is your battery a wet flooded type, or a sealed agm type? Exactly what model is it?

    Any suggestions for a simple charge controller to keep the battery topped off? I definitely want a floating charge, and PW to keep the lead acid deep cycle battery in good shape.
    I think you'll want to define topping off vs maintaining before going further. Topping off to me means enough power to actually charge and not just maintain the current state. And for that we'd need more info on your battery like 20-hour rate capacity, and chemistry gel/flooded/agm ?

    Is this panel permanently mounted, or do you have the ability to angle it while in the slip?

  8. #8
    Junior Member
    Join Date
    Aug 2013
    Posts
    3

    Default

    Quote Originally Posted by PNjunction View Post
    The other issues have been adressed so...

    A 12W panel / cc to a deep cycle battery is more of a maintainer, and not a top-off really. Especially if your panel is horizontal on the boat, and your solar-insolation is poor in the marina. A maintainer will just help offset self-discharge and light parasitic draws and essentially try to keep the battery in the state is was found in, and not really top-off aside from a superficial surface-charge. Given that this is solar, that is only doing it's job about 4 hours a day at best depending on where you sail / moor, so not much is happening. Horizontally mounted, this would be a pipsqueak.

    Is your battery a wet flooded type, or a sealed agm type? Exactly what model is it?



    I think you'll want to define topping off vs maintaining before going further. Topping off to me means enough power to actually charge and not just maintain the current state. And for that we'd need more info on your battery like 20-hour rate capacity, and chemistry gel/flooded/agm ?

    Is this panel permanently mounted, or do you have the ability to angle it while in the slip?
    It's a lead acid flooded cell, Group 27, 105 AH (at 20 Hour Rate), 575 CCA, RC 180 min. I do angle it, and it gets a good 8 hrs. of sun a day, although much of that is obviously off-axis. But what was weird about this is that I left it fully charged, and returned to find it dead. Most telling, after disconnecting the panel/controller and leaving it for 7 days, the battery only experienced minor self discharge. So I'm pretty sure it was the controller/wiring. After reading up more on controllers, I ordered a new one, SunSaver 10, and will certainly check it out thoroughly when installing.

    But one key question is still unanswered - what are your thoughts on putting a load on (i.e. starting the engine) while the panel/controller is connected. Thanks for all the help!

  9. #9
    Administrator
    Join Date
    Feb 2011
    Location
    Annapolis Md
    Posts
    6,201

    Default

    Starting the engine should have no effect on the solar

    The solar should not have caused the battery to go dead unless the comtroller is shorted.
    There are a few other things on boats that are wired directly to the battery. The biggest culprit I have seen kill a battery is the bilge pump.
    If it is an automatic one that senses water and doesn't have a float switch that's where I would start looking.
    Second spot is take a good look at the stuffing box if its an inboard and make sure all sea cocks are shut when you leave the boat.
    The number one cause of boat sinkings are hose clamps and open sea cocks
    Last edited by Naptown; 09-05-2013 at 10:55 AM.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •