Advice on wiring camp trailer batteries - where/how to fuse, etc, etc...

[RV8R]

@skipdup

One of my favourite videos to attempt to help DIYers understand AC “Alternating Current” & DC “Direct Current” & why it is so hard to safely open a DC circuit while under load is this video ,,, you can clearly see the difference in the knife switch about 1 minute into the video when he changes the AC to DC;

This is why you need decent fuse protection @ each battery (positive) terminal in your battery bank.

In that video he is using 220 volts, but even 12vdc batteries can be turned into “Arc Welders” unintentionally. Anyway, that knife switch under load gives you an idea of why your battery fuses are important for AIC in a DC battery.

We flick on & off lights in our houses without thinking about it with 110VAC ,,, because it is AC (@ 60 Hz) ,,, there can be little tiny sparks but 60 Sine waves per second is the reason why that knife switch with AC in the video is benign (120 times a second the voltage is 0 volts);

 

[skipdup]

Here's my plan. Excuse my diagram making skills.

edit: If I add inverter, it will be fused at the busbar.
Also, 12-48v buck converter for ZeroBreeze not shown. But will also be fused at busbar.

Everything will be grounded to busbar (BlueSea 250a).

 

[HRTKD]

What is the 12-48 converter for?

Assuming you keep your wire lengths down, the wire sizes are OK.

I don't know how everybody else does it but I use a third busbar for the grounds. I run a single cable from the ground busbar to the frame.

 

[RV8R]

Here's my plan. Excuse my diagram making skills.

edit: If I add inverter, it will be fused at the busbar.
Also, 12-48v buck converter for ZeroBreeze not shown. But will also be fused at busbar.

Everything will be grounded to busbar (BlueSea 250a).
View attachment 285864

I do not know how many 12vdc distribution circuits you need, but have you considered the Blue Sea Safety Hub 150 ?;

SafetyHub 150 Fuse Block - Blue Sea Systems

Ignition-protected fuse blocks capable of consolidating and protecting multiple 1A to 200A circuits.

www.bluesea.com

200 amps Max for 12vdc & 10 circuits ,,, if you need more circuits you can feed the fuse block you show in your schematic to the Safety Hub.

Note; As the Safety Hub 150 would eliminate your pos & neg bus bars.

On another note; In your case, I am just buying a Victron MultiPlus “Inverter / Charger” rather than 2 120vac chargers & future inverter.

If you do not decide on the Safety Hub 150, then I do not like your neg path thru the 12vdc fuse block ,,, those fuse blocks are good for 100amps IIRC & the inverter plus other loads can be over that I think.


Chassis Ground;

1) Could be off the Safety Hub 150 (lug)
2) Off the -P side on the Shunt

The shunt & the safety hub could probably take 2 wires on 1 bolt ,,, but you can also add a bar to the shunt;

@Q-Dog posted a link to bars you could attach to shunts ,,, but I can’t find that post now ,,, but that is a technique you could use to ensure “balance” @ the shunt “twin” battery negative shunt connection ,,, or just bolt the 2 negative lugs to the shunt 3/8” bolt . Depends if you want to be a “purist” with your LFP battery bank in parallel for “Balance”.

For “balance” the idea is you have to keep the resistance equal right to the singular connection point;

Neg is the Shunt -B side

Positive is the “Load” lug on the 4 way BS Switch ,,, thus in theory the balance point is the Blue Sea Switch.

 

[skipdup]

What is the 12-48 converter for?

Assuming you keep your wire lengths down, the wire sizes are OK.

I don't know how everybody else does it but I use a third busbar for the grounds. I run a single cable from the ground busbar to the frame.

Yes, wire lengths will be short. but I'll be double checking when I actually do it.
The converter is for the zero breeze air conditioner.
Thanks!

 

[skipdup]

@RV8R I plan to leave the existing circuits alone for now (though, I may lower it to reduce strain). It already has a blue sea fuse block. (edit: This one). It feeds fridge, some 12v outlets, water pump, and led lights. My load on that will be light.

If you do not decide on the Safety Hub 150, then I do not like your neg path thru the 12vdc fuse block ,,, those fuse blocks are good for 100amps IIRC & the inverter plus other loads can be over that I think.

Anything with a heavy draw (inverter, 12-48v converter, chargers, etc) will be grounded to the 250a bus bar. Not the fuse block. Or, am I missing something? Thanks!

 

[RV8R]

@RV8R I plan to leave the existing circuits alone for now (though, I may lower it to reduce strain). It already has a blue sea fuse block. (edit: This one). It feeds fridge, some 12v outlets, water pump, and led lights. My load on that will be light.


View attachment 285889



Anything with a heavy draw (inverter, 12-48v converter, chargers, etc) will be grounded to the 250a bus bar. Not the fuse block. Or, am I missing something? Thanks!

Right ,,, Sorry I was looking at that as all new components ,,, so the fuse block & both bus bars are existing right ?

In this case when / if you add an inverter the positive & negative should go to the bus(es) & not pass thru the 12vdc fuse block.

Rule of thumb on 12vdc inverters is drop a zero off the watts to get amps ,,, 1200W is 120amps ,,, might be a bit conservative but ,,, so your “existing” BS fuse block is good for 100amps Max ,,, but 30 amps max per circuit;

ST Blade Fuse Block - 12 Circuits with Negative Bus and Cover - Blue Sea Systems

Compact ATO® / ATC® fuse block consolidates branch circuits and eliminates the tangle of in-line fuses for electronics and other appliances.

www.bluesea.com

You should not run your inverter or chargers thru the existing 12vdc fuse block ;




Follow thru the circuit protection you have above;

Negative side you go from #2 to #10 on the same circuit

Positive side you have no protection & the bus.

Unless I am reading this wrong ?


IMO; You are at a “crossroads” of where you are & where you are going;

Future inverter & maybe a Multi “Inverter / Charger”

Present 2 - 30 amp chargers ??


If you can keep your total under 200 amps, then the Safety Hub 150 “still” might be the way to go for combining the protection & bus(es) into one fuse block that “after review” might be “it” for your present & future needs ?



Or am I missing something on this “thru the internet” spitballing conversation brainstorming ideas here ??

there are times I can be myopic .


I get it; everything will be grounded ,,, that is “too big of a deal” to have as a cursory comment on electrical design IMO ,,, Also ,,, I’m not designing a system like that.

In my Van, where it is true I use my 1 chassis ground as a return path negative for my DC2DC alternator charger, all other circuits are “home run” negative to the negative bus - shunt.


It is possible I misunderstood your phrasing of “ground” ? If you have just not shown the “negative” return wires to the neg bus in your diagram that is different.

 

[RV8R]

What is the 12-48 converter for?

Assuming you keep your wire lengths down, the wire sizes are OK.

I don't know how everybody else does it but I use a third busbar for the grounds. I run a single cable from the ground busbar to the frame.

I read “Ground” as “Ground” also ,,, Now I think @skipdup means “negative side of the circuits” not shown & those are “home run” to the negative bus.

My -P side of my Victron BMV 712 is my negative bus (for my Camper Van) & my “Ground” wire #1 AWG is attached to that 3/8” bolt.

 

[skipdup]

I read “Ground” as “Ground” also ,,, Now I think @skipdup means “negative side of the circuits” not shown & those are “home run” to the negative bus.

Sorry. Yes, that's what I meant. I never thought of this before...

 

[RV8R]

Sorry. Yes, that's what I meant. I never thought of this before...

7. Ground, earth and electrical safety

www.victronenergy.com

Grounding Made simpler - Part 4: Mobile systems.

Jan 29, 2021

How do I ground my RV?

• FilterGuy
• How-to PDF's or Ebook's

That last link ,,, Download the file (part of the screenshot above) & “Drink From the Firehose of Knowledge” ,,, Caveat “If You Care about Such Things”

 

[skipdup]

downloaded. will read.