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Discussion Starter #1
Hi all,
I have searched and have not found an answer or recommendation for my specific scenario. Apologies if this is out there already but it is not clear to me and I have read and searched a lot! Appreciate any help.

With a DCDC Charger connected to the starter battery, do I need to chassis ground my house system negative busbar or is this accomplished already because the van starter battery is connected to the chassis at the factory ground connection?
All of my 12V loads, including the DCDC, have positive and negative leads equal in gauge and length going back to positive and negative bus bars that then connect to my 200AH house battery bank.

Obviously, the van starter battery is connected to the factory ground point between the front seats. Is this sufficient as a chassis ground for my house system as well? I've read having just one single ground point is important, otherwise my plan was to just connect a separate large wire from my negative bus to the chassis.

Some detail...
I have a Renogy 40A DCDC charger with positive and negative 2 AWG leads (oversized for the distance) between the DCDC and my van's starter battery. I will have a 60A MEGA fuse on the starter battery +. With the Renogy DCDC, a 12V ignition feed connection is required to power the unit. I have tapped into the Upfitter connection for this and have added a toggle switch to this wire in the dash to allow me to override the power of the DCDC as most of the time I will have it switched off when driving due to having solar and an inverter charger. Does switching off the power to DCDC charger impact using the factory grounding connection off the negative of the starter battery?

If I end up having to run a separate chassis ground wire from the negative bus, would adding my wire lug to an existing factory ground connection (like the ones at the tail lights) be acceptable?

Thanks!
 

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Not 100% sure if I understand the question. You may have to simplify the question if I'm misunderstanding.
With direct current, the current goes in one direction. Out of the battery, through the load back to the battery, repeat. Constant loop in one direction.
By attaching the negative to the van metal, they can save in wire. They only need to run a positive wire back to the tail lights and use the van metal as the negative or "return" to the battery.
Your DC-DC charger is wired in parallel, inline with the house batteries. It's essentially an extension of your starter battery. The POS&NEG only need to go directly from the starter battery, through the charger and to the house batteries. It doesn't need a "ground" to the chassis like AC,because DC works differently. If that's what you're asking.
 

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Discussion Starter #3
I'll try to simplify my question. Prior to getting the DCDC, my plan was to have a large wire from negative busbar that would be grounded to the van as a safety measure in the case a positive wire were to mistakenly charge the skin of the van. Now that I am installing the DCDC charger, my question is do I still need this large wire from the negative busbar to the chassis?
 

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If your negative bus bar is for your house batteries, you only need the bus bar to attach the negative side of all you loads back to the battery bank negative. You can also attach the negative side of the DC-DC and inverter to the bus bar. No need to attach the house battery neg to the chassis. The neg side of the DC-DC right back to the starter battery neg. Which I recommend.
 

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Discussion Starter #5
Yes, the negative busbar is for the house batteries. I also have one for the positive side. The plan is to have pos. and neg. wires for all loads including the inverter charger and DCDC running back to the busbars. I was just unclear on whether I then needed to attach the negative busbar to the chassis somewhere or if this is accomplished because the DCDC links everything into the starter battery which is attached to the chassis.
 

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Best best is appropriate gauge wires coming directly from pos and neg starter battery terminals, to DC-DC and to house batteries.
Most of the factory van electric uses the van body/chassis metal as a return to the stater battery.
All your house stuff is going to your house batteries and yes, those are connected to starter battery via the DC-DC charger.
No need to ground the house system to the chassis.
Did you run an equally sized neg wire from the DC-DC charger back to the starter battery? Or just to the the van metal, right where you mounted it?
 

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Discussion Starter #7
Appreciate the replies.

DCDC charger is mounted at the rear of the van near the house batteries, as the manual said have it close to the batteries being charged. I have 2 awg from the positive terminal of the starter battery to the DCDC then 6 awg from the DCDC to the pos busbar. Slightly oversized wire vs the manual recommendations. Same thing on the negative side: 2 awg from the negative terminal of the starter battery to the DCDC then 6 awg from the DCDC to the negative busbar.

2/0 cable connects the bus bars to the house batteries.
 

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Discussion Starter #9
I mentioned this in the original post and just want to be sure
The Renogy DCDC requires a third wire that gives power to the unit when the ignition is on. I connected this to an ignition feed pin in the Upfitter Connector. I want to have have a toggle switch on this signal wire in the dash to allow me to have the DCDC off when I don't need it charging while I am driving.

This may be a dumb question but will having power to the DCDC switched off impact the circuit and chassis ground?
 

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I'm going to say it won't hurt anything.
I want to say that the charger regulates the charge and does so according to the state of the batteries. It shouldn't overcharge the batteries. But it's always a good idea to have a shut off on any system/circuit.
Did you use one of the aux buttons on the dash?
 

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Discussion Starter #11
No, I didn’t investigate the aux buttons I’m just adding my own switch. Or that was the plan at least
 

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Discussion Starter #12
Updating on this.

After getting confirmation from Renogy that the negative will always pass through the DCDC charger even when it is not powered on and that a chassis ground of the house system would be unnecessary, I went ahead and installed the DCDC, as noted above, with negative and positive leads to the starter batter and the house battery bussbars.

Well, turns out there is no continuity through the negative on the DCDC charger when the charger is off (confirmed by more than one multimeter) and Renogy was just well....wrong.

Would the proper action now be to have a large wire from the negative load busbar to somewhere on the chassis/van metal to ensure a safety chassis ground? Does having this chassis ground somewhere other than an already established factory ground location cause any issues?
 

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So are you having any trouble with this? I'm assuming you are since you're asking still.

I'm a noob and so while I did read your thread earlier, I didn't feel qualified to reply.

All I know is that my install works and is similar in concept to yours except that I don't do any grounding. I'm not quite sure why grounding is needed.

Here is a simplified diagram of what I've done. It worked from day 1.

67476


By "switch on dash", I don't mean any of the AUX switches. It's just a simple SPST switch.

I tapped into the cig lighter adapter because that's controlled by the ignition switch. I didn't want the Renogy to siphon power from the engine battery when the engine (alternator) wasn't running.

By "simplified drawing", I meant that I have circuit breakers all over the place (not shown) and I didn't mention the size of the cable, which is relevant only to my installation; use the right-sized cables for yours.

Also, my switch has an indicator light so I've a bit more wiring than what I show, but that's a nicety, not technically required.
 

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Discussion Starter #14
No, I am not having any issues. Everything is working fine, except without continuity through the negative on the DCDC while it is off, I now realize by house batteries are not ground to the chassis.

I also wired a switch into the dash like you. I connected mine into the upfitter connection next to the passenger seat
 

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Good luck finding a definitive answer to this. It's hard to go wrong using the factory point and probably the best practice, though it could be a long run. On the other hand probably nothing bad would happen if you used a different point just make sure it's free of paint and securely connected to the rest of the chassis, which is kind of iffy in these vans that seem like they are glued together.

I would contact Renogy again and see what they say, maybe your unit is faulty.
 

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I have the opposite question... I have connected the positive input on the DC to DC charger to my car battery positive, but am wondering if it is necessary to run the negative input on the DC to DC charger all the way back to the car battery negative, or if it is possible to only run it to the chassis ground, which I am currently connecting my negative bus bar and house battery to back near the battery. I have a factory bolt that seems to work well as a ground as it goes down into a welded thread in the frame. Can anyone help me with this?
 

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It would work but using the chassis for a return path is less reliable over time than running a cable. Your charger is going to push a fairly high current over a long period of time so the if there are any problems with the return path through the chassis the likely hood of a fire or something is greater.

Keep in mind these vans have unibody frames that are basically glued together.
 

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It would work but using the chassis for a return path is less reliable over time than running a cable. Your charger is going to push a fairly high current over a long period of time so the if there are any problems with the return path through the chassis the likely hood of a fire or something is greater.

Keep in mind these vans have unibody frames that are basically glued together.
Possibly, but doesn’t Ram ground the starter battery to the chassis?
 
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