Understanding bar

[galladanb]

Hey Guz an gals, I am learning sooooo much in here! THANK YOU ALL!!!!

RoamingKat, in case you missed it, here is the page that I am cloning.
http://www.builditsolar.com/Projects/Vehicles/PMRV/Electrical/Electrical.htm
I will follow this almost exactly... HE has some very good diagrams and images
for those of us, mostly me that can follow along in crayon!!! LOL!

In your diagram above in the margins, you ask if the "Inverter / Charger direct to battery"?
For me YES, that is how the Tripp lite wants it. It has a decal on it saying:
"Battery(S) must be connected for V - Output to be Present"

I have this morning come up with a new question not previously covered in here or over there...
I want to install those big red handled cutoff switches...
https://www.amazon.com/gp/product/B005DUUL9W/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1

And he has used what he is calling breakers that look like cutoffs...

MY question, do I install those big fuses before the red switches or does his perform both tasks
of cutoff and breakers??? And what Amperage fuse should I go with?

 

[Optimistic Paranoid]

At full power, 1250 watts / 12 volts = 105 amps.  So probably a 120 or 150 amp fuse or dc circuit breaker.  And yes, SOME circuit breakers have a manual push button switch built in.  Such as this Blue Sea breaker:

https://www.bluesea.com/products/7189/285-Series_Circuit_Breaker_-_Surface_Mount_150A

 

[VanKitten]

So...my picture was correct Ground bar to shunt to battery..battery ground to chassis.

 

[highdesertranger]

no, the ground to the battery that you have labeled as NEG has to go to the shunt on the side of the ground bus. if you do it like your picture your meter will not measure anything your have grounded to the chassis, like your alternator. in other words your meter will not record the contribution of the alternator. highdesertranger

 

[VanKitten]

Optimistic wrote. :


If you don't ground the house battery to the chassis, you will get no charging from the engine alternator because there would be no return path to complete the circuit.


So, I am confused. I have a ground return from the busbar. The shunt is on that ground (neg post).

The ground to chassis you refer to .... I connect it to the ground Before I connect to the shunt? After the shunt? If after...isn't that the battery?

Do I splice the line between the shunt and the battery neg post? how is that different than just grounding the battery neg post to chassis anyway? Do I splice the ground line between the neg busbar and the shunt....one to shunt..one to chassis. Doesn't that mean I would fail to measure anything with the monitor?

Ok... but..I have to ground to chassis. So where do I splice in the line to chassis?

See my confusion?

 

[Weight]

I see your confusion. I don't understand how you are confused. The chassis ground connects to the bus bar. The battery negative connects to the bus bar. The alternator and any other things that ground to the chassis return to the battery through the bus bar. The only thing the battery negative connects is to the buss bar.

 

[VanKitten]

Seems simple. Just one question....if the ground to the chassis is coming straight off the busbar...then what is going through the ground wire from the busbar to the shunt? And then on to the ground on the battery. Isn't all the charge being "dumped" to chassis (from the busbar) before the shunt?

 

[VanKitten]

Ok...maybe you mean there is no connection between the battery negative and the busbar? The busbar grounds to the chassis...end of story?

So..ground busbar to shunt to chassis?

 

[John61CT]

Do not rely on the chassis, especially for heavy loads, always come back to the ground buss, same length/thickness wiring as positive.

Yes connect that buss to your bank negative, but the "master shunt" used for bank SoC monitoring needs to be between it and the bank so every amp flows through it.

 

[VanKitten]

I am so confused.

I seem to be getting information that contradicts each other.

Can we all agree on some diagram? Please.

 

[Optimistic Paranoid]

OK, I think this partial diagram should clear things up.  Remember one simple principal.  Everything that you want to measure has to pass through the shunt.  Any current that either leaves the battery, or goes in to the battery that doesn't pass through the shunt, WON'T get measured.

In our original diagram, we had the inverter getting it's power directly from the battery.  If we want to measure the power that the inverter is pulling - and we do - then the inverter has to be hooked up to the buss bars and not directly to the battery.  That means that the buss bars need to be able to handle the HEAVY wires that the inverter needs, and the wires between the battery and the buss bars need to be equally heavy.  That includes the wires to the shunt, as seen in this diagram.

 

[Weight]

There you go. John got it for you. Don't forget a fuse on the positive battery, the red line.

 

[VanKitten]

Thank you! That is the wiring I will use.


I don't know why the ground won't just go straight to the chassis..leaving nothing for the monitor to observe. But, honestly....my knowledge is barely reaching the point where I now know what I don't know! Thank you for the diagram!

 

[highdesertranger]

thanks OP that is what I was trying to get across. only 1 wire to the negative battery post and that goes to the shunt. highdesertranger

 

[John61CT]

http://www.pbase.com/mainecruising/image/131690814

 

[Optimistic Paranoid]

I don't know why the ground won't just go straight to the chassis..leaving nothing for the monitor to observe. 

In DC circuits "ground" isn't really ground in the same sense as it is in ac circuits.  Just think of it as a return path, the same as if you were running a wire between the front and back of the vehicle.

 

[John61CT]

Which is why it's better to use the terms “negative” or "return" or "negative return" for DC, and why those wires should be yellow rather than black.

 

[Optimistic Paranoid]

Which is why it's better to use the terms “negative” or "return" or "negative return" for DC, and why those wires should be yellow rather than black.

In the automotive world, we tend to use red for positive and black for negative.  In the boating world, because live-aboard boats often have ac as well as dc, and ac uses black for hot, white for return, and green for safety ground, they've moved over to using red for positive and yellow for negative on dc.  That way there is no confusion as to what a black wire is.

Unfortunately, the RV world has not followed suit.

 

[galladanb]

Hmmm, sorry for dredging up older threads, but..

I'm doing my ground system, and I have a question, well 2 really...

Concerning the shunt, what are you all using to secure it down?
There are no bolt holes... I guess I will try something with plastic of some kind...
Does it heat up in regular use?

Also, second question, can I use the system side as kind of a buss bar?
I want to mount the inverter ground, the distribution panel ground,
and the solar n the same post... Is that a good idea?

Ok third question...
I've ask before in other threads, but I don't think I ever got an answer to this one...
The inverter has 2/0 to battery ground, then i can only have 2awg for the 12v distribution,
and the solar is only 8awg...
My question is it ok to mix sizes in each grounding system?

Here is a picture of my shunt with grounds kinda setup like I want to use them.
Left 4awg ground from inverter, middle 4awg from distribution panel, solar ground not yet installed, and the tight hand 2awg ground to chassis...
Does this make sense?

 

[John61CT]

Here's a guide for the shunt looks good

http://canalworld.net/forums/index.php?/topic/13364-how-to-guide-installing-an-ammeter-shunt/