Victron SmartSolar Charge Controller Case/Chassis Ground (SmartSolar 100/20)

ChrisFix
ChrisFix Member Posts: 743
in Battery/Electrical & Solar
I'm preparing to install a Victron SmartSolar 100/20, and ran across something I hadn't planned on.
The SmartSolar 100/200 has a case or chassis ground screw - which I do not see on the 75/15 unit that is factory installed.
I've searched for info on this, and the best I can find is that Victron says you should connect the ground screw to a chassis ground of the RV, but users are about equally split if it is necessary.
Electrically, it is not needed for the 100/20 to operate properly...but it is for safety if something malfunctions and voltage gets to the heatsink i guess.

Can a case ground like this be connected to the negative of the battery distribution block?
If not, does anyone know where the 2021 400 chassis ground point is?
Thanks in advance...
2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,542
    I didn't ground mine a couple of years ago, but who knows?  This thread, on a different subject entirely, shows the junction box in the trailer.  It has pictures and descriptions of the wiring setup, and one is listed as a grounding lug.


    2017 Outback
    Towed by 2014 Touareg TDi
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  • CrabTab
    CrabTab Member Posts: 457
    edited August 2021
    @ChrisFix Ground and neutral conductors are commonly attached to the same bus bar in the main panel of residential systems. The purpose of the ground is designed to be a safety fail for an open (disconnect) of the neutral. Sounds like this is the same concept here.

    I believe the controversy about the need for a separate ground of 12VDC  circuit is that they are usually low amps and aren't a human safety issue (But can surely damage electronics, as you mention).

    Hope this helps...

    2019 320 Boondock Edge     - Sold Jan 2022
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  • ChrisFix
    ChrisFix Member Posts: 743
    pthomas745 said:
    I didn't ground mine a couple of years ago, but who knows?  This thread, on a different subject entirely, shows the junction box in the trailer.  It has pictures and descriptions of the wiring setup, and one is listed as a grounding lug.


    @pt@pthomas745
    Like I mentioned, I'd say the internet responses to this were about equally split on "ground it or you'll burn down your camper", and "why bother".  So you are not alone in not having bothered.
    I had seen (and forgotten) the link you sent - and it makes me disinclined to run a wire all the way from the far back to the tongue for this.  

    2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
    2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • ChrisFix
    ChrisFix Member Posts: 743
    CrabTab said:
    @ChrisFix Ground and neutral conductors are commonly attached to the same bus bar in the main panel of residential systems. The purpose of the ground is designed to be a safety fail for an open (disconnect) of the neutral. Sounds like this is the same concept here.

    I believe the controversy about the need for a separate ground of 12VDC  circuit is that they are usually low amps and aren't a human safety issue (But can surely damage electronics, as you mention).

    Hope this helps...
    @CrabTab
    Thanks. I did see a number of posts discussing exactly that issue - that it isn't a real safety risk for a 12VDC circuit.
    Do you know if connecting the case ground to the battery distribution box ground is viable? That must be wired to the grounding lug at the front of the camper, right?
    2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
    2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • ChrisFix
    ChrisFix Member Posts: 743
    I found a post on the forum that discussed the 12V ground bus bar near the WFCO of a 320. I haven't had a chance to look yet, but I have to think my 400 has the same. Given the 2021 400 WFCO is near the install point for Victron, that may be a reasonable way to ground the Victron case.
    But I would love to know if connecting the Victron case ground directly to the negative terminal of the battery distribution block isn't just as good (and is definitely easier).
    2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
    2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • ScottG
    ScottG Administrator Posts: 5,655
    I've learned recently that chassis grounding of 12VDC devices is a hotly debated and apparently complex subject. While there is no safety concern (as with the 120VAC side) and 12VDC devices to not require the ground to operate properly, lack of such grounding may be result in electrical gremlins such as ground loops and phantom voltage potentials. Confused yet? Wondering why it matters? Join the club!  ;-)

    @ChrisFix, to get back to your specific question, on my 2015 "320" the 12VDC negative bus near the converter is grounded to the chassis via one of its mounting screws (which is apparently driven through an aluminum frame member under the floor). Newer models feature a wire connecting the 12VDC negative terminal in the forward junction box with a nearby bonding screw on the frame.

    Therefore, the battery negative, the negative leads from all 12VDC devices, the negative terminal in the forward junction box, the 12VDC negative bus, and the chassis are all interconnected. Theoretically, that suggests that is shouldn't matter where in that network you connect the ground, but I have a nagging feeling there is more to it than I am comprehending.

    For lack of better understanding, I would probably connect to the chassis ground screw adjacent to the forward junction box, rather than directly to the negative battery terminal.  
    2015 T@B Max S (320)
    2015 Nissan Frontier SV V6 4x4
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  • ChrisFix
    ChrisFix Member Posts: 743
    @ScottG
    Thanks.
    I've come to those same conclusions as well.
    The 12VDC ground bus and the -12VDC of the battery each have a direct connection to the distribution box at the front of the trailer. And from that distribution box12VDC ground terminal, there is one wire connecting to the actual ground lug of the frame.
    So both battery negative and the 12VDC bus have the exact same electron path, but I think if you get into the various codes, you're still not supposed to connect to the battery negative - and I honestly don't know why.

    2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
    2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • ChrisFix
    ChrisFix Member Posts: 743
    edited August 2021
    For future reference on 2021 T@B 400 BD with 2-way fridge - here is the 12VDC Ground bus Bar. It is below the lower drawer beside the fridge. There is an access hatch that gives (relatively) easy access. And there is one open ground terminal! I looked inside the WFCO panel, and there are zero open ground terminals for the AC side of things - in fact one terminal already has two conductors - which if I remember correctly from a house pre-purchase inspection, is a no-no.


    2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
    2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • ChrisFix
    ChrisFix Member Posts: 743
    And a completed install of the Victron SmartSolar 100/20. 
    I need to pick up wire to run the case ground to the 12V bus bar...but it is already charging the batteries!




    2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
    2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • ChrisFix
    ChrisFix Member Posts: 743
    edited August 2021
    And the moment of truth - drilling the hole!!


    2025 T@B 400 Boondock Black Canyon with 400Ah Battle Born and Victron Multiplus 3000
    2025 Honda Ridgeline Black Edition with Redarc Trailer Brake Controller
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  • Bayliss
    Bayliss Member Posts: 1,506
    Looks like a "hole in one," @ChrisFix!  Perfect.
    2019 T@B 320 S Boondock Lite; 2025 Toyota Tundra CrewMax 4x4
    (Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePO4; Solar: Renogy 220W Portable Suitcase w/ Victron SmartSolar MPPT 75/15 Controller; Victron BMV-712 Battery Monitor w/ Shunt; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
    Greg & Marlene (Tucson, AZ)


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