Chassis Grounding my Campervan's DC Sysytem - need some advice

Luther
Luther Registered Users Posts: 3 ✭
in Solar Beginners Corner #1
I am installing my electrical system in my DIY Campervan build.  The major components of my DC system is a Renogy 200 Amp gel 12V deep cycle battery, Xantrex 1800 inverter/charger, and two Renogy 100 amp solar panels and a charge controller.  I am using two heavy duty blue sea bus bars, one positive and one negative, to organize the wiring and minimize connection to the battery and the inverter/charger.  My DC negative side throughout the van is connected with wiring back to the negative bus bar (I choose not to do a use the chassis ground method for the negative side).   After reading what I can about grounding, I believe I should "Chassis ground" my inverter/charger (It has a chassis grounding stud) and my 200 amp battery negative stud (Does anyone disagree?).  So my question is, instead of running a chassis grounding wires from my inverter/charger grounding stud and from my batteries negative side stud to the vehicle chassis (two wires and two more holes in my floor) can I just run a chassis ground wire off my negative buss bar and achieve the same thing or would that be problematic? 
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  • myocardia
    myocardia Solar Expert Posts: 118 ✭✭✭
    edited September 2018 #2
    Luther said:
     can I just run a chassis ground wire off my negative buss bar and achieve the same thing or would that be problematic? 
    That is the normal way to do it, when using buss bars. You would be much more likely to have problems if you didn´t ground the bus bar to your chassis. Just make sure to scrape or sand away the paint, then rub dielectric grease onto the bare metal, if you want it to be maintenance free. It almost always hel­­­­­­­­­­­­­­­­­­ps kee­­­­­­­­­p the wire from corroding, if you will also a­­­­­­­­­p­­­­­­­­­ply a generous amount of the grease onto the strands of the wire, as well.
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
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  • Luther
    Luther Registered Users Posts: 3 ✭
    #3
    So, should I run a wire from my inverter/charger's chassis grounding stud to the negative bus bar too or just leave the chassis grounding stud not used?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
    Depends on how you mounted your AC inverter... If it is mounted to a wood (non-conductive) surface, then yes--You need to run a chassis ground conductor.

    If you mounted the inverter to a piece of structural metal with good chassis ground connection--You may get away without the chassis ground cable.

    Remember the chassis ground cable is there to "short to ground" any internal shorts in the AC inverter and trip the fuse/breaker from the battery to the AC inverter's DC input. Many larger inverters need a 100-250+ Amp breaker/fuse. So that chassis ground connection needs to be able to take a >600 Amp surge (just mounting to RV sheet metal--That kind of surge will just vaporize thin steel or aluminum metal sheets).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Luther
    Luther Registered Users Posts: 3 ✭
    #5
    Thanks so much for the information. My inverter is mounted to Wood so I will run a ground cable to the chassis too, as you suggest. So a question about the grounding point. I was eyeballing a unused seatbelt connection point which has a threaded bolt into a threaded reinforced hole on the sheet metal floor. Do you think this is a sufficient chassis grounding point or would it be better to drill out the hole and connect to the main Support beam of the van?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #6
    Problem with vehicles is that grounding is hot and miss. HAM radio folks sometimes have to put braided cable grounding between every major part of the car (hood, to each door, chassis to frame, to sub frames, to battery, etc.).

    Generally, your DC cables from battery to inverter are quite short. Running a cable from chassis to battery ground is usually not hard.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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