Wiring layout challenge :) Help needed!

[Stepandwolf]

Protection of the inverter connection would be the battery fuses and BMS protection.

ANL not so bad IMO for smaller branch circuits due to more resistance in the wire.

Breakers on both wires creates more connections. More connections is not going to help simplify the layout. Not to mention two extra bus bars.

Never a fuse has opened on my RV power system in 20+ years. Should take a real fault to open the fuse. Should be extremely rare for fixed components.

Yes a switch is nice on the panels. Saves about 60 seconds every 5 to 10 years when something needs service. Same with the inverter switch.... in the very rare case it needs service a cable can be lifted.

Either way works. Trying to stick with the simplicity side to lay out the components in limited space.

Appreciate the perspective, but I am not sure what the diagram would look like doing it your way. Would be nice to have a way to compare my original design, Rob's version, and your version.

 

[Stepandwolf]

shrug - I dunno then - connecting everything to the chassis ground still leaves it on wheels - unless it is plugged into a pedestal for shore power there is no earth to reference...

If I ever buy an RV I'll deep dive the subject...

And aside from writing novels instead of answers we established in another thread I like building rube goldberg machines.

Since both of you are WAY over my head, would you, based on the discussion, change the first, less complicated drawing? I think the only change was the PV breaker to 40A, otherwise you still like the original?

 

[time2roll]

Thanks for coming to the party....the more of you discussing the build, the better.

Most of my wiring is at or greater gauge than my original drawing. I have 2/0 for the batteries. Other than the PV wiring which is 10ga, where my diagram has 10ga, I actually have 8ga.

"Covered ANL fuse to branch circuits off the positive bus to the controller and DC supply."
Are you saying an ANL where my original drawing has a 60a breaker?

"Use same size 40A to the DC converter to simplify spare items."

Is the DC supply and DC converter the same thing?

Sorry for my confusion borne out of ignorance.

Yes the 40A works fine instead of the 60A connecting the controller to the bus. Yes 40A to the DC converter/supply is fine. Then a single spare 40A fuse covers both. Unlikely to ever need the spare. Said fuses close to the bus bar.

 

[time2roll]

To be clear, are we talking about the factory supplied panels, wiring, etc? I showed one chassis ground in my drawing. Is there some other grounding I need to do other than that?

The negative bus should have a frame ground connection.

The inverter should call for a separate chassis ground to bond the case to RV frame direct. This is a separate independent ground. Separate from DC bus and AC ground. Install manual will give details.

 

[time2roll]

Appreciate the perspective, but I am not sure what the diagram would look like doing it your way. Would be nice to have a way to compare my original design, Rob's version, and your version.

I am not a graphics expert. I will try with a description.

Inverter on one side, controller and DC converter on the other side.

Positive and negative bus bars in the middle. With space near positive bus for 40A fuses feeding controller and DC supply converter. Space next to negative bus to connect the shunt.

Of course batteries and solar are not on the board. Battery fuses on the battery.

 

[jcollman]

Sorry, I write novels to explain things and why I do things


This is the Victron install guide recommendation for fuse and wire size

https://www.solar-electric.com/lib/wind-sun/Victron-Service-Manual-MultiPlus-3k-120V-%28firmware-xxxx4xx%29.pdf

View attachment 277621

Which version do you have?

The size of the class T used should be 300amps or 400amps, you

Changed the breaker size from the PV panels to more closely match the MPPT - 40amp verse 60amp

Amazon.com

Fuse to the buck converter - I would switch to this type breaker verse the automotive breaker -

Amazon.com

Automotive breakers that self reset like the ones you picture can cause problem because you don't know if it is tripping and resetting - no indication ... I much prefer something I have to flip back so I know to watch for problems.

Both of these layouts require 4 bus bars to avoid stacking lugs. -- if you want to make changes - download drawio and use the two attached files ... it takes about 20 minutes on youtube to learn the basics.

Those are 200amp MRBF fuses to go onto your battery post - or you can put them at the bus bar end of things. They require a holder.. I say the bus bar end because I haven't seen a picture of the battery and if it has terminal lugs the output cables are connected to or if you are just bolting directly to the positive cell and the BMS. Terminal lugs is for sure the way to go on that.... safer and the MRBF can't hurt anything if you torque it down to spec.... I get mine from pkys.com or mouser... There are many cheap copies on amazon that don't stand up to actual use...

One thing I see that is missing is an equalizer to run on each string to keep the 2 batteries in sync - being home built and you can monitor the cells for runners that may not be an issue the typical new user with store bought batteries would need to add one.

The plastic enclosure you have on the table will hold both of the dihool black breakers

Note - on the bus bars I picked the particular stud things connect to on purpose






And here it is with the additional large MCCB instead of the switch -- gives you a single switch to turn off the batteries... a second switch to turn off the MPPT... and a third switch to kill power to the buck converter and DC panel.

The advantage of the MCCB is you can turn it off while there is a full load on it with no damage -- the standard switch in the first drawing is only meant to be turned off while there is no load. If turned off repeatedly with a load the contacts get burnt and it starts running hot.

I am assuming the AC out has a fuse or breaker built into the existing panel as does the DC panel. If they don't have that something would need to be added.

I hope it's OK that I leveraged your drawio files for my design.

 

[robbob2112]

I hope it's OK that I leveraged your drawio files for my design.

Be my guest, I posted them to make things easy

 

[Stepandwolf]

ok guys... I did a merge of Rob's awesome design, changed the batteries, and T2R's input into kind of a merger. Would appreciate comments on this latest version. BTW, this is not an attempt to depict physical layout which I won't attempt until the electrical design and components are correct. Appreciation for your constructive criticism.

 

[robbob2112]

Took a minute

I'm not a fan of stacked lugs, but it eliminates a pair of bus bars...

The 6awg wire from the mppt to the breaker and on to the bus bar can be 8awg verse 6awg

 

[Stepandwolf]

Took a minute

I'm not a fan of stacked lugs, but it eliminates a pair of bus bars...

The 6awg wire from the mppt to the breaker and on to the bus bar can be 8awg verse 6awg

I think there are only 3 stacked connections. The two positive battery connections will be connected with bare wire to the T1 which I have seen done. I think the shunt can also accommodate two wires. Right or wrong, that was my plan
8ga vs 6ga is because it is what I already bought for this project. Should the chassis ground wires be 8ga?
Thanks!

 

[Stepandwolf]

With more detail so you guys have more to correct me on

 

[robbob2112]

My problem with stacked connections is that the stacked lugs are not as flat as just a lug per... which means a lot of the torque is spent flattening the lugs together and if they are thick enough you might not get flat enough...

if you must stack - no more than two on a post - *loops for small currents don't count* ... but when doing stacking the lug with the most current goes closest to the bus bar/post ..

Your choice to do it - and I have done it to avoid an additional bus bar at times...

Going bigger on the wire doesn't hurt anything so use the 6awg since you already have it.

I don't know what the size rules are on a mobile install other than the ground wire should be sufficient to clear any faults. This is a table used for stationary installs - from it I would assume 10awg copper for the bus bar and 6awg from the inverter
EGC sizing


And once you get it all assembled - with one hand in a pocket touch everything after it has been running a bit... start with back of hand so if you catch a jolt you jerk away verse grab.... see if anything is hot

 

[Stepandwolf]

My problem with stacked connections is that the stacked lugs are not as flat as just a lug per... which means a lot of the torque is spent flattening the lugs together and if they are thick enough you might not get flat enough...

if you must stack - no more than two on a post - *loops for small currents don't count* ... but when doing stacking the lug with the most current goes closest to the bus bar/post ..

Your choice to do it - and I have done it to avoid an additional bus bar at times...

Going bigger on the wire doesn't hurt anything so use the 6awg since you already have it.

I don't know what the size rules are on a mobile install other than the ground wire should be sufficient to clear any faults. This is a table used for stationary installs - from it I would assume 10awg copper for the bus bar and 6awg from the inverter
EGC sizing


And once you get it all assembled - with one hand in a pocket touch everything after it has been running a bit... start with back of hand so if you catch a jolt you jerk away verse grab.... see if anything is hot

Thanks for all the tips. You are a great resource.

 

[Stepandwolf]

was looking at buying more battery wire. I had originally bought 2/0 from Windy Nation. When checking the price for 1/0 I found the cable sold for the same price. Other than the flexibility of the wire, why would I spend the same for the smaller 1/0 cable?

 

[robbob2112]

Which other wire? Both welding wire?

Sometimes these guys have clearance items that are a buck a foot cheaper.

Wire & Cable Your Way: Electrical Wire By the Foot

We are a trusted online distributor of electrical wire and cable products, offering fast shipping on a huge selection of SKUs, cut-by-the-foot or in bulk.

www.wireandcableyourway.com

For batteries you can using welding wire, battery wire, silicone 200c or DLO cable.... the welding isn't typically UL listed, but the DLO is for an inspection

 

[Stepandwolf]

Which other wire? Both welding wire?

Sometimes these guys have clearance items that are a buck a foot cheaper.

Wire & Cable Your Way: Electrical Wire By the Foot

We are a trusted online distributor of electrical wire and cable products, offering fast shipping on a huge selection of SKUs, cut-by-the-foot or in bulk.

www.wireandcableyourway.com

For batteries you can using welding wire, battery wire, silicone 200c or DLO cable.... the welding isn't typically UL listed, but the DLO is for an inspection

Yes, both welding wire. Don't think I have seen DLO even mentioned. Did eventually find some 1/0 for slightly less than 2/0. I did Google search but only found best pricing at Amazon where I get 5% off and free shipping. Thanks

 

[robbob2112]

I ran into DLO cable when researching all things cable -- and stumbled on the fact that pretty much the only welding wire that is UL listed is bright yellow.

This doesn't matter since the welding cable is of a known spec and capacity from the mfg... but if you are being inspected in an area where the inspector is a dick he could fail you from using a non-UL listed part.

I've ordered some DLO (diesel locomotive cable) and it is pretty much like the welding wire except it has a slightly higher temp rating and the sheath is thicker, but slick on the outside... bendability is slightly less easy because of the thicker sheath.

@Daddy Tanuki turned me onto the DLO cable as an alternative to welding wire for batteries.

 

[Stepandwolf]

I ran into DLO cable when researching all things cable -- and stumbled on the fact that pretty much the only welding wire that is UL listed is bright yellow.

This doesn't matter since the welding cable is of a known spec and capacity from the mfg... but if you are being inspected in an area where the inspector is a dick he could fail you from using a non-UL listed part.

I've ordered some DLO (diesel locomotive cable) and it is pretty much like the welding wire except it has a slightly higher temp rating and the sheath is thicker, but slick on the outside... bendability is slightly less easy because of the thicker sheath.

@Daddy Tanuki turned me onto the DLO cable as an alternative to welding wire for batteries.

I think the only time an inspection would be done is on a grid-tie system. Neither of my setups is grid-tied. I have watched many installs and have yet to see one with yellow cable. Found a UL listed cable at your favorite wiring site and it is orange

4/0 Welding Cable Class M UL/CSA

4/0 Welding Cable Class M UL/CSA

www.wireandcableyourway.com

And this 2/0 which is also orange:

Flexible Cord & Welding SPEC 70300

cabletechsupport.southwire.com

If you scroll down this page you will see a black one:

Kalas Welding Cable - Kalas Wire & Industrial Cable

Kalas Welding Cable manufactured & professionally designed. Durable flexible & industry’s best-selling welding cable with value-add services & customization

www.kalaswire.com

"As a highly flexible cable featuring a CPE jacket, our Type W portable power cable is RoHS compliant and constructed to meet both UL Subject 1650, CSA PPC 22.2 – 96 and MSHA flame test approved requirements. Appropriate for use in accordance of National Electrical Code (NEC) article 400 and NFPA 70 for generator leads, battery leads or motor leads, heavy duty or temporary power supplies and light to medium duty mining applications."

I really appreciate all your great advice.

 

[Daddy Tanuki]

a lot of it revolves around the entity making and selling it. in reality almost all welding cable will pass but it boils down to if they did the paperwork to get approved for a multiple uses or not.