You opinions/advice please - Location, Location, Location

[lafamaku]

Hi, We are purchasing a 2021 22MLE. I am in the middle of planning the solar install. The dealer is providing me one of their electrical techs on an hourly basis to help me. For me that is the best of both worlds - I get to control the design and sizing and he can help me with the install for the electrical work that I may not be the best at. Also, nice to have another set of eyes.

Here is the situation: The 10 gauge wire from the rood comes into the pass through by the convenience center. If I put my components there, I will need to run a large 4-0 or 2-0 line to the WFCO that is located in towards the middle of the trailer. However, there is a dinette seat right next to the WFCO and between that and the space under the pantry right next to the dinette, where the WFCO is located there is enough room for the components which would require me to run a longer line from the panels to the dinette area.

Here is the question. Which will provide the best efficiency for the system? Leave it in the pass through and be closer to the solar or put it in the dinette and limit the length of line to the WFCO?

Thanks in advance for your insight.

[howson]

I will need to run a large 4-0 or 2-0 line to the WFCO that is located in towards the middle of the trailer.

Why? How much solar are you putting on the roof?

Choosing a wire size is all about the maximum current expected along with the length of the run.

For example, I have a 1200W system and have 2 ga wire going from the Victron 150/100 controller to the battery bank. The highest rated output of the controller is 100A. Under ideal conditions I may see up to 88A (1200W/13.6V). I don't know the exact length from controller to battery bank, but I'm sure it's <12'.

My fellow mod, TucsonJim , frequently references this chart from BlueSea as authoritative: http://assets.bluesea.com/files/reso...on_chartlg.jpg

With a solar setup I recommend consulting the "CRITICAL" column for the length of wire. Using my numbers above from my setup, the 90A column shows my 2 AWG wire is more than sufficient for my relatively short run.


Use the same process to choose the right wire for your configuration. I seriously doubt that 4/0 or even 2/0 is required IMHO.

Sorry I can't address your specific question about location and efficiency except to say "shorter wires are better". Don't forget to get approval from "the boss" (if you have one) on the location if the controller is visible.

Howard

[BillM321]

I also have a 22MLE and have been contemplating whether to put the solar charge controller and a LiFePo battery up front in the storage pass-through or under the seat in the dinette close to the WFCO power center. I am not a solar expert or Electrical Engineer, but my thinking is that it would be better to have loss between the solar panels and controller since that is running at higher voltage than it would be to have the losses between the controller and the battery where it is trying to push higher amps at a lower 14.4 voltage. But I am not sure about that and would also love some input on my reasoning.

Since you said you were ordering your trailer, then I assume you don't have it in your possession to look at and crawl around on, under, and through. So maybe this will help.

The best I can tell.....

The factory pre-run wires from the solar junction box on the roof to the pass-through storage compartment are 10gauge and look to be about ~8 feet of wire from the roof down. I think the intention was for us to mount our solar charge controller at the end of those wires in the storage compartment. Then there looks to me to be around 10 feet or so of the same type of 10 gauge wire then running under the floor and out onto the frame on the curb side. At that point the wires from the tongue-jack/breakaway/original battery and solar all meet on a 30amp breaker on the frame near the junction box for the 7-pin trailer wiring that connect the truck and the trailer (silver box in pic #2). From that breaker area on the frame there are 8guage wires running back about 16 feet to the WFCO power center.

So if you put your solar charge controller up in the front storage compartment like GD intended, but put the battery under the dinette seat, and then use the existing wiring that GD installed, you would have about 10' of 10AWG connecting to about 16' of 8AWG for a total of ~26' of wire between the output of the solar controller and the battery. I don't know how much voltage drop that would cause but I suspect that what the solar controller is putting out and what the battery is actually seeing will be quite different.

Once it warms up I plan to try and drop the underbelly liner on the trailer and see how hard it would be to run new 6AWG wire from the front storage to the WFCO power center area. Or....I was thinking I could just forget about using the pre-installed solar wires on the roof at the front of the trailer, and instead put a new junction box on the roof right above the closet area between the bathroom and dinette. Then I could drop the solar panel wires straight down through that closet to a solar controller. Then with the controller close to the battery, it would greatly reduce voltage drop.

I saw that Smart Victron MPPT controllers and their new Smart Shunt will talk via Bluetooth. This allows the MPPT to know exactly what is happening out at the battery and adjust the output of the controller to help compensate for voltage drop happening at the battery end. But I think I read it can only can handle 1v of drop, and I suspect using the 26' of 10AWG/8AWG that is factory installed in the trailer will be much more than 1v of drop.

Here are some pics I took of what is under the dinette seat and also behind the WFCO power center just on the other side of the wall of the dinette. You can see the giant hole in the floor where all the wires are fed into the back of the WFCO power center. The red arrow shows the 8AWG wire from the front of the trailer coming into the WFCO area. IT looks like there is a lot of room under that dinette seat for a LiFePo battery and other items like a MPPT and inverter. I am not too crazy about mixing the water pump and battery all in the same area if there was ever a water leak. But I think it could be dealt with.

Hope this helps in some small way. I will be very interested in how you resolve this issue.

Billm321

[lafamaku]

Why? How much solar are you putting on the roof?

Choosing a wire size is all about the maximum current expected along with the length of the run.

For example, I have a 1200W system and have 2 ga wire going from the Victron 150/100 controller to the battery bank. The highest rated output of the controller is 100A. Under ideal conditions I may see up to 88A (1200W/13.6V). I don't know the exact length from controller to battery bank, but I'm sure it's <12'.

My fellow mod, TucsonJim , frequently references this chart from BlueSea as authoritative: http://assets.bluesea.com/files/reso...on_chartlg.jpg

With a solar setup I recommend consulting the "CRITICAL" column for the length of wire. Using my numbers above from my setup, the 90A column shows my 2 AWG wire is more than sufficient for my relatively short run.


Use the same process to choose the right wire for your configuration. I seriously doubt that 4/0 or even 2/0 is required IMHO.

Sorry I can't address your specific question about location and efficiency except to say "shorter wires are better". Don't forget to get approval from "the boss" (if you have one) on the location if the controller is visible.

Howard

This was helpful. I was aware of the table, but was shooting from the hip. Last time I do that.

[lafamaku]

I also have a 22MLE and have been contemplating whether to put the solar charge controller and a LiFePo battery up front in the storage pass-through or under the seat in the dinette close to the WFCO power center. I am not a solar expert or Electrical Engineer, but my thinking is that it would be better to have loss between the solar panels and controller since that is running at higher voltage than it would be to have the losses between the controller and the battery where it is trying to push higher amps at a lower 14.4 voltage. But I am not sure about that and would also love some input on my reasoning.

Since you said you were ordering your trailer, then I assume you don't have it in your possession to look at and crawl around on, under, and through. So maybe this will help....

The factory pre-run wires from the solar junction box on the roof to the pass-through storage compartment are 10gauge and look to be about ~8 feet of wire from the roof down. I think the intention was for us to mount our solar charge controller at the end of those wires in the storage compartment. Then there looks to me to be around 10 feet or so of the same type of 10 gauge wire then running under the floor and out onto the frame on the curb side. At that point the wires from the tongue-jack/breakaway/original battery and solar all meet on a 30amp breaker on the frame near the junction box for the 7-pin trailer wiring that connect the truck and the trailer (silver box in pic #2). From that breaker area on the frame there are 8guage wires running back about 16 feet to the WFCO power center.

So if you put your solar charge controller up in the front storage compartment like GD intended, but put the battery under the dinette seat, and then use the existing wiring that GD installed, you would have about 10' of 10AWG connecting to about 16' of 8AWG for a total of ~26' of wire between the output of the solar controller and the battery. I don't know how much voltage drop that would cause but I suspect that what the solar controller is putting out and what the battery is actually seeing will be quite different.

Once it warms up I plan to try and drop the underbelly liner on the trailer and see how hard it would be to run new 6AWG wire from the front storage to the WFCO power center area. Or....I was thinking I could just forget about using the pre-installed solar wires on the roof at the front of the trailer, and instead put a new junction box on the roof right above the closet area between the bathroom and dinette. Then I could drop the solar panel wires straight down through that closet to a solar controller. Then with the controller close to the battery, it would greatly reduce voltage drop.

I saw that Smart Victron MPPT controllers and their new Smart Shunt will talk via Bluetooth. This allows the MPPT to know exactly what is happening out at the battery and adjust the output of the controller to help compensate for voltage drop happening at the battery end. But I think I read it can only can handle 1v of drop, and I suspect using the 26' of 10AWG/8AWG that is factory installed in the trailer will be much more than 1v of drop.

Here are some pics I took of what is under the dinette seat and also behind the WFCO power center just on the other side of the wall of the dinette. You can see the giant hole in the floor where all the wires are fed into the back of the WFCO power center. The red arrow shows the 8AWG wire from the front of the trailer coming into the WFCO area. IT looks like there is a lot of room under that dinette seat for a LiFePo battery and other items like a MPPT and inverter. I am not too crazy about mixing the water pump and battery all in the same area. But I think it could be dealt with.

Hope this helps in some small way. I will be very interested in how you resolve this issue.

That was super helpful I plan on installing the 420 Watt Kit from Continuous Resources. So 420 Watts of Solar on the top and 2 - 100amp Battle Born Batteries.

[lafamaku]

That was super helpful I plan on installing the 420 Watt Kit from Continuous Resources. So 420 Watts of Solar on the top and 2 - 100amp Battle Born Batteries.

I also think between the Dinette and the pantry there is enough room to handle the components. I also want to make sure the system design is as efficient as possible.