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  • Grounding a battery

    So I was talking to a buddy of mine, who is reading everything he can gets his hands on about Solar and he asked me "why do you need to ground a battery"?

    to be honest, I had never thought about running a ground rod to the negative post?

    If the Array is grounded, and the panel box is grounded, why would you need a ground rod to the negative terminal of your battery bank?
    I don't get drunk~~~~I get awesome

  • #2
    So the fuse or breaker will operate on the positive terminal if by chance the positive is shorted to the chassis or a grounded object.
    MSEE, PE

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    • #3
      would there be any concern about a sky to earth lightning strike? could a strike hit near by and go back up the ground? would it hurt the batteries?
      I don't get drunk~~~~I get awesome

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      • #4
        shouldn't we be grounding the positive?
        NABCEP certified Technical Sales Professional

        [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

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        • #5
          Originally posted by Naptown View Post
          shouldn't we be grounding the positive?
          In an ideal word grounding the positive is what we would prefer. But unfortunately most manufacture hard wire the chassis in common with Negative. So if you were to ground the positive you would let the magic smoke out. Some of the better manufactures float both polarities which gives you the option to float the system, or ground either polarity.

          FWIW all telephone offices ground the positive on -48 volt battery plants. It comes from the old days when outside plant cables were sheathed in lead. If the grounded the negative will causes a cathodic erosion of the lead sheath dissolving it into the earth. Ground the positive and you reverse the cathodic action and it protects the sheth by adding deposits.

          At all airports, pipe lines, Disney, Refineries, etc they use cathodic ground protection systems. It uses DC with a positive ground to protect the ground electrodes in the earth from corrosion.
          MSEE, PE

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          • #6
            I'm not sure what this is going into it may not be a car or RV
            NABCEP certified Technical Sales Professional

            [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

            [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

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            • #7
              we have seasonal property in the North country (Adirondacks) and we are getting into solar. at first all we wanted to do was charge a couple batteries.

              Now it looks like are getting more serious.

              At this point we are charging two 6v golf cart batteries in series.

              But this question of grounding batteries came up, so I figure I better ask someone that knows

              Thanx for the responses
              I don't get drunk~~~~I get awesome

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              • #8
                Originally posted by Jmac00 View Post
                At this point we are charging two 6v golf cart batteries in series.
                At this voltage and power level it is not required to ground the system. What is important though is that there be over current protection. So if you are not grounding the system you will have to add protection devices to both polarities.

                It is called floating a system which is very safe and reliable. If one polarity becomes faulted to ground nothing happens and everything keeps right on working like normal. Then when the other polarity goes to ground the over current protection devices operate and shut the system down.

                Go into any factory, oil refinery or anyplace where service interruptions are unacceptable and costly, the do not ground the systems. Grounded systems are dangerous and unreliable.
                MSEE, PE

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                • #9
                  Originally posted by Sunking View Post
                  At this voltage and power level it is not required to ground the system. What is important though is that there be over current protection. So if you are not grounding the system you will have to add protection devices to both polarities.

                  the system is grounded. We have a standard Cutler-Hammer breaker box and the solar panels have a Morningstar charge controler on them. But Im probably going to up grade that to a Outback or Xantrax MTTP controler, as soon as money becomes available

                  I also want to to add a small wind generator at some point in the near future (maybe towards the end of the summer) where we are located we get a good wind coming off the lake.
                  I don't get drunk~~~~I get awesome

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                  • #10
                    Originally posted by Sunking View Post
                    At this voltage and power level it is not required to ground the system. What is important though is that there be over current protection. So if you are not grounding the system you will have to add protection devices to both polarities.

                    It is called floating a system which is very safe and reliable. If one polarity becomes faulted to ground nothing happens and everything keeps right on working like normal. Then when the other polarity goes to ground the over current protection devices operate and shut the system down.

                    Go into any factory, oil refinery or anyplace where service interruptions are unacceptable and costly, the do not ground the systems. Grounded systems are dangerous and unreliable.
                    Where would be the proper place to put the OCPD between modules and CC or between CC and battery?
                    NABCEP certified Technical Sales Professional

                    [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                    [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                    [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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                    • #11
                      Originally posted by Naptown View Post
                      Where would be the proper place to put the OCPD between modules and CC or between CC and battery?
                      At the sources. (Modules and battery post.)

                      Or do it just like you would if you grounded the system, except no ground rod or earth connection. That way only one OCPD on each polarity. Understand?

                      Just like a car ground system.
                      MSEE, PE

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                      • #12
                        Getting fuses inside a door operator could be a challenge. Or are we just talking on the solar side and not the load side on the battery.
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                        [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                        [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                        [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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                        • #13
                          Originally posted by Naptown View Post
                          Getting fuses inside a door operator could be a challenge. Or are we just talking on the solar side and not the load side on the battery.
                          Well crap, that did not dawn on me. Alright as close to the battery box as possible. The controller is not a source, only the panels and batteries are sources. Like any source you want to install OCPD as close to the source as possible.

                          If you stop and think about it, it makes perfect sense. If you were to put the OCPD at the utilization device, you have all that wire in between the source (power) and the load device, all that wire is left unprotected. That is why your main breaker panel is installed extremely close to the meter.
                          MSEE, PE

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                          • #14
                            Rich thinking out loud here, but if this is a 1-panel system, you do not need to fuse the panel. It does not gain you anything. Well providing the wire size is correct. You can short the panel all day long and nothing will happen. Th epanel cannot generate enough current to burn up the wire, and the voltage is not high enough to electrocute anything..

                            Is there any AC circuits in this garage or anything that might accidentally make contact> Something like a overhead service feeder falling on the panel or structure?
                            MSEE, PE

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                            • #15
                              #10 USE2 wire for everything, 1 12V 60W panel, Nothing electric within 50' Nothing overhead all underground.
                              There may be an OCPD within the operator. The motor is 600W.
                              NABCEP certified Technical Sales Professional

                              [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                              [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                              [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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