Please review Travel Trailer system wiring diagram

bluewaterbound · March 2018

Hello,

I'm new to this forum and new to travel trailers. We recently purchased a new Camplite 21RBS where I'm in the process of installing dual batteries, Inverter and Midnite KID solar with 4x100W flex panels. I have attached a system/wiring diagram of the what I'm currently installing and will be powering up in the next day or 2.
I would appreciate any feedback on the design to ensure a proper and SAFE system before I power up!

Here is a link to the diagram.

https://drive.google.com/file/d/1u4LBLNZ-x3RFyzVJLR83fl8qLZscGmIY/view?usp=sharing

Thank you!

Estragon · March 2018

Some quick comments:
- the max breaker size should be on the panel spec labels. Rigid panels are typically 12-15a max and I'd be surprised if flex ones are higher.
- I'd go with the biggest wire that fits on the kid output to minimize voltage drop.
- wire and breaker sizes should be specified by manufacturers of charger and inverter makers.
- 2000w inverter is pretty big for a 12v system. It will take a fair bit of power just being on with light loads. You'll want to turn it off when not in use. Presumably most loads will be DC, and the inverter is for a microwave or other short but heavy load.

bluewaterbound · March 2018

Thanks for comments.

Correct the 2000W inverter is large and is sized for running microwave OR expresso machine for a few minutes each.
Yes, the size of the inverter may draw too much when doing sitting idle and is designed to turn on/off easily, Thanks!

All breakers and wires sizes are to spec. This goes for power center, inverter and solar. Wire lengths are short runs in all cases.
i.e. all 1/0 wire positive lengths add up to <= 3.5 ft. total. Same for 1/0 negative lengths.

ScoobyMike · March 2018

I could be all wet here but I am not 100% sure about tying the inverter and charger chassis to the RV chassis. Does the Kid have DC GFP? The Classic manual states "The battery negative and DC source negative must not be connected to the system grounding conductor anywhere in the system. Grounding these circuits will defeat the GFP function". Is the earth ground on the rest of the RV AC system tied to the chassis?

bluewaterbound · March 2018

Hi Mike,
Thanks, you nailed my main issue.

The Midnite Solar KID has a DC GFP that I have not shown because I’m still trying to get some definitive answers about how to hookup battery negative (chassis connect or not) and ground (chassis connect or not). The factory setup had a single battery negative connected to the frame nothing else. The power center had all DC negative leads connected to a common bus bar that was connected to the frame as well as AC ground. AC neutral and ground are not bonded (by code only bond and that is done at shore power panel). So my question is do I disconnect the battery negative from frame and leave grounds to frame? Or float ground or something else? I’ll be installing the GFP today that connects between battery negative and ground and basically disconnects the PV+ during fault. As shown now it should trip as you state.

Right now I’m leaning towards disconnecting trailer frame from battery negative.

ScoobyMike · March 2018

I am far from an expert here and I hesitate to give you advice on this important point. There are several other threads discussing RV grounding, do a search on "RV Grounding". @BB has some good thoughts in these various threads, I'm sure he will pick up on your thread soon.

bluewaterbound · March 2018

Basically all grounds go to frame. That includes AC ground from shore and all chassis grounds of components. Battery negative is also connected to frame. I included the DC-GPF from Midnite Solar in the final diagram (see share link). I system tested today and every thing worked fine. Wire length came up in a few reviews I had from other sources. Note that the "round trip" length of the 1/0 cable is less than 8 feet. from battery terminals to inverter and back.

https://drive.google.com/file/d/1AiWjGybEZ3KIQ4LFSY9wKqJRupICEiEP/view?usp=sharing

Enjoy

BB. · March 2018

BlueWaterBound,

One minor correction I would make is to your battery bank grounding to the chassis ground... i suggest that you move it from the negative battery post to the common negative bus on the other side of the shunt.

With vehicle loads, many use the chassis as the return for power (DC lighting, automotive radio, and such). Where you have the chassis to battery ground now will "miss" any loads that happen to return current through their chassis ground connection(s).

The battery bank is small for a 2,000 Watt @ 12 VDC inverter... Nominally, I would be suggesting a 500 Watt maximum continuous AC load. (2,000 watts * 1/0.85 AC inverter eff * 1/10.5 volt battery cutoff=) 224 Amp nominal current flow at max AC inverter rating.

1/0 cable is NEC rated for ~125 to 170 amps (in conduit)---And if you were going to really run the inverter near 2,000 watts for longer periods of times (more than a few minutes), I would be suggesting a 1.25 Wiring+Breaker derating (224 amps * 1.25 derating=) ~280 Amp minimum rated Branch Circuit DC current.

If you use the less conservative Marine Wiring standards, 1/0 is good for upwards of 285 Amps

https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

You do not show breakers/fuses for some of the wiring leaving the positive bus bar for some of the other DC loads (hitch plug, cooling fan)--You should have protection for those connections too (fuses/breakers rated to size of wiring).

-Bill

bluewaterbound · March 2018

Hi Bill,
Thank you for the comments.

The inverter runs a 400w fridge while towing and during sunshine (propane the rest of the time) the 2000w is sized to run a microwave OR an espresso machine for few minutes otherwise could use a small one. 1/0 wire is fine given the short round trip length. I remeasured and it is <7 feet. 1/0 high strand copper is good for 300a 12v DC <=7.9.

I thought the 200a breaker on the inverter would be just enough for the microwave, fridge an some misc low wattage items but it tripped with everything on high. I think I will need 225a and a 275a for the main battery disconnect.

Thanks for pointing out no fuse on the hitch plug, I will put one in for that. All others DC and AC circuits are fused/breaker through the power center.

About the battery chassis ground before the shunt. I checked that all the DC negatives came back to a common ground bar at the power center but it is possible something took a shortcut. Good idea on moving the ground to other side of the shunt.

Thanks

littleharbor2 · March 2018

Will you have a TV and satellite system? If so and if 120 volt you might consider an additional smaller inverter. Personally I would investigate installing a larger battery bank. This is where AGM batteries tend to work well, being they can be installed in odd locations, and in odd positions.

bluewaterbound · April 2018

Thanks for the feed back. Yes, running the TV/Satellite is powered by the inverter. I did add a third battery to the system. If I required more than 300ah of battery I would probably go with 300ah of these : CALB 100AH LiFePO4 Prismatic Battery (CA100FI).
Here is the final installation:

https://drive.google.com/file/d/1k1u7b9DNDewI6zEt2IWHHqJsnjeQBSXQ/view?usp=sharing

David_in_San_Diego · April 2018

Hi Bluewaterbound - Could I please trouble you to let me know what tool or software you used to create your wiring diagram? I've been looking for awhile and that seems perfect.

All - I'm also open to any other suggestions re same?

Thank you.

bluewaterbound · April 2018

David,
I used Mac Keynote since I no longer have Windows Office due to cost. Keynote is free for Mac users. There are some other tools for free as well Google docs. Note: Keynote is very limited if you are use to using Visio or Frame Maker.

Here is the updated system after a couple of trial runs.
The cheap circuit breakers from Amazon are junk and I returned all but one (T Tocas 250 Amp Manual reset) This one holds up under 140 amp load for 5 minutes. Nothing worked for the 300A to the battery. Ended up with a standard battery switch/fuse combo.
In the end I added an extra battery for a total of 300ah and 2 more solar panels for a total of 600W.

https://drive.google.com/file/d/1kH6Re7Pk2ivEXQFnbcwVwZGleqsJFNec/view?usp=sharing

Please review Travel Trailer system wiring diagram

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