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Discussion Starter #1
Hi Everyone,

I'm at that point where I am ready to start purchasing wires, breakers and switches OH MY!
Anyhoo I have sifted through all the diagrams I have found online and built a good understanding of a 12v system and I think I have a decent diagram going.

BUT! I have seen WILDLY varying sizes of cable being used (particularly between batteries) and it makes me second guess myself, makes me fell like I am missing something. For instance I have seen people use 4/0 welding wire between batteries while only having 300amp hrs of total batteries. First off that crap is expensive! And second in all of my cookalations I cant see how one would need a 400amp rating. I already feel like I am going overboard with using 2/0 but came to that conclusion simply out of fear. Please Help me out! I know there are some smart folks out here.

One other thing. Do you think it is redundant to have switches in line when I could just flip a reset-able breaker when I need to isolate the system from the energy sources? ie Starter Battery, Solar and House batteries?
 

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MMXVI - L2H2 in IN
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1000w inverter for a microwave, from what I read good luck.
12ga for 12v led lights, I used some old 22ga [email protected] wire, seems to work fine.
14ga works fine for 120v appliances.

You need to know the voltage, the load and the distance both ways.

I could go on, but I won't.
 

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2017 159, w/dual sliders. SF Bay area
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Without knowing the distances, it is hard to provide feed back on specific sizes. As long as you used something like the Blue Sea guide, you'll be fine.

Why do you have a black line and a green line coming from the solar charger? Actually, why do you have any green lines on the DC side?
 

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Believe you need to go to 2000W PSW for even a 700W microwave. Even that combo has had issues reported on the forum. On the Battery place the positive and negative at the opposite ends (Bat 1 and Bat 3), you may be doing that but the diagram shows otherwise.
 

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As a reference, my 1.1 cuft wattage unk works fine with my 2k psw inverter.
 

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I'd wire your solar panels in parallel to a combiner box on the roof instead of series. I'd then use a 6awg cable from your combiner box to the solar charge controller. 6awg is overkill for 300W, but if you want to upgrade down the road you'll be happy you have the correct size cable.
 

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Discussion Starter #8
I'd wire your solar panels in parallel to a combiner box on the roof instead of series. I'd then use a 6awg cable from your combiner box to the solar charge controller. 6awg is overkill for 300W, but if you want to upgrade down the road you'll be happy you have the correct size cable.
Thanks that was a recommendation direct from Renogy. The logic i believe that the MPPT solar charger I am using will get better results with higher voltage? Any reason to go Parallel over series in this case?
 

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Believe you need to go to 2000W PSW for even a 700W microwave. Even that combo has had issues reported on the forum. On the Battery place the positive and negative at the opposite ends (Bat 1 and Bat 3), you may be doing that but the diagram shows otherwise.
Thanks on the Inverter, Trying to cut costs somewhere.

As for the Battery linkage Ive seldom seen batteries wired in parallel that way. What is the logic? Does it make for a more even pull among the batteries?
 

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Discussion Starter #10
What sort of DC heater is that? I don't see any fans.

I think you'd be better served to list your fuse ratings rather than saying "all fuses match cable ratings".

As Thom says, there's no distances or device loads so it's hard to comment on your wire sizes.
Sorry I didnt add the fan, I have a Maxx im about to install as well. Its a Propex FYI

As for the Fuse ratings, This is why we are talking. I wont be able to list that until I have determined the gauge of the wires needed.
 

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Discussion Starter #11
Without knowing the distances, it is hard to provide feed back on specific sizes. As long as you used something like the Blue Sea guide, you'll be fine.

Why do you have a black line and a green line coming from the solar charger? Actually, why do you have any green lines on the DC side?
Blue sea distances, Yeah Im working with that and Ill fine tune it if I can on the long runs. My MAIN concern is with the heavy gauge stuff. Ill be well over rated for the DC stuff as far as I can tell but as Iwas saying in the intro, LOTS of people are using 4/0 to link there batteries and i dont understand why.

Grounding? Glad you asked. Every darn piece of equipment talks about grounding requirements so Im trying to comply. Where the solar charger has an actual grounding terminal i cant remember so i added in the diagram as a reminder. Why do we need grounding when the vehical never touches the ground? I have no idea. Will it hurt to throw a ground to the chassis? You tell me please!;)
 

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Discussion Starter #12
1000w inverter for a microwave, from what I read good luck.
12ga for 12v led lights, I used some old 22ga [email protected] wire, seems to work fine.
14ga works fine for 120v appliances.

You need to know the voltage, the load and the distance both ways.

I could go on, but I won't.
Thank you, yeah I am over rated with the 12v stuff and Im ok with that as i already have the wire. Im mainly trying to figure out why people put 4/0 to link the batteries. Seems like expensive overkill.

Also aside from cable gauge Im hoping to see if my overall design is lacking something critical. For instance Im a bit lost on grounding.
 

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Blue sea distances, Yeah Im working with that and Ill fine tune it if I can on the long runs. My MAIN concern is with the heavy gauge stuff. Ill be well over rated for the DC stuff as far as I can tell but as Iwas saying in the intro, LOTS of people are using 4/0 to link there batteries and i dont understand why.

Grounding? Glad you asked. Every darn piece of equipment talks about grounding requirements so Im trying to comply. Where the solar charger has an actual grounding terminal i cant remember so i added in the diagram as a reminder. Why do we need grounding when the vehical never touches the ground? I have no idea. Will it hurt to throw a ground to the chassis? You tell me please!;)
OK, all stop. Not to be a jerk, but you are on a dangerous course. You are a bit over your head and you can kill somebody if you get this wrong.

I've seen recommendations for this book, but have not read it myself.

https://smile.amazon.com/No-Shock-Zone-Electrical-Safety-Michael-Sokol/dp/0990527913/

"ground" is a fundamental concept. In DC lines, it is the return path to the power source. In AC lines, it is more of a safety net. Very different things, inspite of using the same word.

Wikipedia to the rescue.

https://en.wikipedia.org/wiki/Ground_and_neutral
 

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One other thing. Do you think it is redundant to have switches in line when I could just flip a reset-able breaker when I need to isolate the system from the energy sources? ie Starter Battery, Solar and House batteries?
Blue Sea 187 and 285 series breakers are designed for this.
 

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Discussion Starter #16

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OK. DC circuits only - many people use the chassis as the ground.
 

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Discussion Starter #20
Its a start


Sent from my SM-T810 using Tapatalk

Thanks. I should be more clear. Based on the same calculations and charts that everyone is using, and accounting for even a 10% voltage drop (despite only traveling less than 1 foot between batteries and less than 2' to a fuse or any buss or distribution block) I never come up with any reason to run more than 1/0 for this area.
Can anyone either tell me what I am missing or confirm that these people are overcompensation HEAVILY by using 4/0?
 
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