To ground or not to ground

Djkozware

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Nov 19, 2020
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Hi y’all:

This is my first set up going in my DIY RV. I have:
2 48v 105 ah batteries from big battery.com
An mpp Solar lv6548
And 3050 watts of panels on the roof.
You’ll also notice the dc converter or step down in the attached picture to go from 48v to 12v.
My question is, do I absolutely have to attach a ground wire from my negative bus bar to the chassis of the Rv?
I have seen in Will’s videos with the lv6548 in his trailer, that it is not grounded to the chassis. So I’m curious if I can avoid putting the extra hole in my floor.
Thanks
A1712E15-7EBA-4DFA-8382-776BDBB54361.jpeg
 

12VoltInstalls

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There’s a current discussion going that answers your questions and has reasons why.
Post 583 has a short answer but read from pg27ish for context instead of random information.
 

Djkozware

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There’s a current discussion going that answers your questions and has reasons why.
Post 583 has a short answer but read from pg27ish for context instead of random information.
More questions came about than answers after reading through that. Now I’m confused about way more stuff. Ground neutral bond? Grounding the AC side of things… wow… I thought this would be much easier 😭
 

12VoltInstalls

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Well read the short answer in post 583 and come back here to ask away.
I absolutely have to attach a ground wire from my negative bus bar to the chassis of the Rv?
Will it ever be on “shore power?” If no then the answer is yes. If it will ever be on shore power then you have to determine what strategy of basically two strategies are required to disconnect the neutral and bare ‘ground’ when shorepower provides the bond.
That keeps you from energizing your frame with deadly electricity as in the other thread.
 

Zil

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For DC currents. You do not necessary have to attach the negative battery to the RV chassis. You should always run a negative cable back to the BusBar for any critical or high use devices. I have a negative to chassis connection. That allows lesser devices such as fans and lights to have chassis negative connections with only the positive wire from the battery. It also allows case lugs on certain devices to connect to the chassis.
For AC currents using a shore line connection you must certainly have a 'ground' connection through the shore line to campground pedestal. The green wire must connect to the chassis.
 

Djkozware

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For DC currents. You do not necessary have to attach the negative battery to the RV chassis. You should always run a negative cable back to the BusBar for any critical or high use devices. I have a negative to chassis connection. That allows lesser devices such as fans and lights to have chassis negative connections with only the positive wire from the battery. It also allows case lugs on certain devices to connect to the chassis.
For AC currents using a shore line connection you must certainly have a 'ground' connection through the shore line to campground pedestal. The green wire must connect to the chassis.
Instead of having a traditional “shore power” hook up, I was just planning on using the lv 6548’s ac input. Connecting is to a shore inlet and plugging in that way instead of wiring the shore directly to my panel. Is that acceptable? Or there an issue with just running everything directly through the lv6548? Will I still need to ground the AC stuff to chassis that way? Or do the N-G bond?
 

Djkozware

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With a 48V system it seems as though it makes logical sense to assume he is using 120VAC…
I will be running a few things from the 48v bus bars where my batteries are connected to. Then to a 48v to 12v converter. So there will be some DC loads that will bypass the inverter
 

12VoltInstalls

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You do not necessary have to attach the negative battery to the RV chassis. You should always run a negative cable back to the BusBar for any critical or high use devices. I have a negative to chassis connection. That allows lesser devices such as fans and lights to have chassis negative connections with only the positive wire from the battery.
That is confusing. You say it isn’t necessary and then say the busbar but you never mention the safety aspect; so many things at 12V could have an unplanned device to chassis neg(-) through mounting screws etc.
No matter what IMHO a batt(-) to chassis is a reasonable safety precaution.
Also, I never use chassis as a “ground” but homerun + and - to a single point (like what the bluesea fuseboxes conveniently enable) that terminates to the battery bank.
 
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