Can you offer advice on an expandable RV setup?

[AllByteNoBark]

Hello, new here and new to solar stuff. I am fairly handy and know enough to be dangerous I guess. Looking for some help on the start to an expandable system for an RV.

We have a 5th wheel RV that came with a Xantrex X 2000 inverter, and a WFCO WF-9855-AD Deck Mount Converter Charger. It also came with two 85AH lead batteries. It is supposedly "solar ready" which kind of looks like a joke to me as far as wiring from the roof, light gauge and 20 amp fuse on it. A quick audit is showing around 3.5 to 4.0kWh of power used per day for our type of use. No air conditioning, residential fridge, laptop, Starlink, lights, water pump, and LP furnace with temps running in the 40s. I am hoping to get so I can run a couple of days off battery in cloudy conditions. We do carry a generator but would like to use it as backup only.

Would like to keep this simple to start with. Thought about a 24v or 48v system but the auto level is a pretty heavy load so am thinking maybe I should stick with 12v for simplicity. Also everything can be in close proximity so the heavier gauge wiring the 12v requires does not hurt quite so badly.

My thought was to get 2 x 12v 400AH batteries to replace the lead batteries. Have not got the roof measured yet for panels but would plan on adding them in two or three of months when I have a bit more time. The Xantrex will work for us for now. Not sure on the charger, do not want to harm batteries trying to save a few dollars, thoughts?

I just do not know what I do not know. Any helpful insight would be appreciated.

Thanks in advance!

 

[MisterSandals]

3.5 to 4.0kWh of power used per day

I am hoping to get so I can run a couple of days off battery in cloudy conditions.

3500Wh x 3 = 10500Wh

10500Wh / 12.8V = 820Ah (double that for usable)

The weight of 1640Ah of batteries is prohibitive all by itself!
94lbs per 200Ah ... ~750lbs!

Lithium 61lbs per 200Ah (only need 820Ah since 100% usable)
61lbs x 4.1 = 250lbs

 

[AllByteNoBark]

3500Wh x 3 = 10500Wh

10500Wh / 12.8V = 820Ah (double that for usable)

The weight of 1640Ah of batteries is prohibitive all by itself!
94lbs per 200Ah ... ~750lbs!

Lithium 61lbs per 200Ah (only need 820Ah since 100% usable)
61lbs x 4.1 = 250lbs

Yes, same math I used, that is why I am planning on the 2x 12v 400AH Lithium batteries. I did not make that clear above. The batteries I am looking at are 106lbs apiece. The lead batteries in use now weigh 100lbs for the two.

 

[Grith]

I am new here and perhaps in the same boat as yourself.
I have used the EcoFlow Delta Max 2000 portable lithium battery power pack which I originally purchased and use in my trailerable yacht as a drop in expansion to my existing 280amp hour agm system in my slide on truck camper which we also use for extended away from civilisation travel like the yacht.
It gives me 240v grid like power which I just feed into the camper and yachts shore/domestic power systems whilst accepting charge from my about 600w of solar individually fitted to both of these.
Whilst many here may scream there are cheaper way to do this it works for me with the portability between use locations also acting as my rain water tank pumps solar based power supply when we return to home base for period of recharge and reset for our next travels.
It has worked so well I have just purchased a second unit giving me 336ah of lithium storage and all sorts of multiple uses and redundancy backups.
Waited for black Friday type extreme specials to purchase both significantly lowering the upfront very high cost.
In the yacht they are very securely fitted under the dinette seats in perfectly fitting hatches with attached plastic storage boxes available through marine stores.
In the camper they are also fitted under a dinette seat just using some of their original packaging for stability.
The neat feature is remote control switching and monitoring of all inputs and outputs giving me a good understanding of loads, charging and storage capacity all on my phone app.

 

[12VoltInstalls]

just do not know what I do not know. Any helpful insight would be appreciated

You actually DO know what it is you don’t know and you are trying to find out?

thinking maybe I should stick with 12v for simplicity. Also everything can be in close proximity so the heavier gauge wiring the 12v requires does not hurt quite so badly

That would be my assumptions and conclusions as well.

Have not got the roof measured yet for panels but would plan on adding them in two or three of months when I have a bit more time

Flat installed solar panels will compromise output potential of the panels. But you probably know that. Typically one would wildhat guess you need summed panel wattage ~20% of the daily watthour sum.
In your case my wildhat guess would be a lot more panel watts than that. I’d suggest ~1000W of panels minimum. That will allow consumption with plenty of capacity to charge the battery bank in 5 hours or so.

 

[AllByteNoBark]

When I get to the panels I will mount as much as I can fit. My wild guess is I can get around 1600 to 1800 on the roof. Be nice to get more but I do understand the limitations of my space and the panels being flat.

Thanks for the input.

 

[12VoltInstalls]

Wow. Nice.

~1800W panels, flat, should be 5-6000Wh daily in decent sun at a very conservative wildhat guess.

 

[RoadTurtle]

I'm finishing an "upgrade" on my 5th wheel. Few things I've learned, from the factory and my first upgrade. This upgrade is ripping out everything and starting over.

First and this is not something to take lightly, pay very close attention to how close you are to things like air conditioning and vents and other stuff on the roof. I intentionally went with 200w panels and mounted them all the way to the outside edge to avoid shadows as much as possible.

3 panels on each side wired as separate strings. I can add one more on drivers side, but it will cover the bath sky light, which I really don't want to do. I couldn't lift panels above the roof junk, because I'm already at legal height.

 

[12VoltInstalls]

3 panels on each side wired as separate strings

That’s a wise move imho

 

[Zwy]

I would leave the legacy 12V system with converter in place with one lead acid battery, no solar or inverter to run the leveling system. Install a switch for power to the converter, this allows you to turn it on/off in order to charge the 12V lead acid battery. The reason for this is due to the load requirements of running the leveling system, the motor draw at startup may trip the BMS of a LFP battery.

I would move to a 48V inverter system for a large 5th wheel. This prevents the wasted money down the road syndrome when you decide you want a larger system. For the 12V accessories other than the leveling system just use a buck converter. I split all my 12V accessories off the original system on my truck camper, the only item still on the converter and original fuse box are the jacks on my truck camper. The converter has a switch so I can turn it on/off when I need to run the jacks, I actually removed the 12V lead acid battery now and just use a jump box clipped to two posts where the old lead acid battery resided (weight reduction and I don't remove the camper often). I installed a new fuse panel powered by a 24V to 12V buck converter and moved all 12V circuits to it.

 

[AllByteNoBark]

Thanks to everyone for the input so far. AS this is my first solar build I want to keep it as simple as possible and still accomplish the results I am looking for. In researching I found the below diagram and am planning on building my system out close to it.



Any comments on the design or changes that might make it better would be welcome. Some modifications I plan on making:

1. May need to update the MPPT to s different size
2. Probably will not add a DC-DC charger
3. My generator will just feed through the shore power plug

Tell me what I am missing.

 

[AllByteNoBark]

I would leave the legacy 12V system with converter in place with one lead acid battery, no solar or inverter to run the leveling system. Install a switch for power to the converter, this allows you to turn it on/off in order to charge the 12V lead acid battery. The reason for this is due to the load requirements of running the leveling system, the motor draw at startup may trip the BMS of a LFP battery.

If I have two parallel batteries 100 amp BMS's can I still only pull a max of 100 amps? I do not think I would ever hit that many amps from what I have seen testing, but your point is a good one. If it came to it, I could supplement with the gen if needed. Typically the unit seems to only move at most 2 of the jacks at once from what I have seen.

 

[Zwy]

2 batteries in parallel will allow twice the amps. The biggest problem with any 12V system is limitations of the lower voltage. Larger cable sizes, more amp draw, heating of components. Once you get above 2000W, it's usually better long term to move up on voltage. I run a 3000W inverter on 24V. For my house, the 6500W inverters are 48V.

 

[Chaucer]

Hi,

I've been advise to have the cut off switch before the Class T-fuse so everything is cut off from the battery if needed (even the fuse) . Beginner here...seen it both ways, not sure of the prefered way.

Could the Class T fuse be tied into the bus bar and the cutoff switch moved before the busbar. That way, the one cut off switch from the battery stops power to every everything?

Just asking because I have a very similar system and that is what I did. Maybe it makes no difference?

tks

 

[Zwy]

Fuse before the switch is preferred.

 

[HRTKD]

I have a 30 amp trailer using a Victron Multiplus 12/3000 fed by two 12v 280 Amp LiFePO4 batteries. It works fine for my use. I run the rooftop air conditioner and even charge my EV. Your two 12v LiFePO4 batteries should work just fine to run the leveling system. Don't make the system any more complicated than you have to.

The solar charge controller in that diagram is way undersized for the amount of PV you plan to use. Consider using two 100/50 solar charge controllers (at a minimum). Victron has a nice MPPT calculator you can use to figure out the exact solar charge controller you need.

With that much solar, I don't think you're going to need any charge from the tow vehicle. You can skip the DC-DC charger and especially don't use Renogy.

 

[AllByteNoBark]

I have a 30 amp trailer using a Victron Multiplus 12/3000 fed by two 12v 280 Amp LiFePO4 batteries. It works fine for my use. I run the rooftop air conditioner and even charge my EV. Your two 12v LiFePO4 batteries should work just fine to run the leveling system. Don't make the system any more complicated than you have to.

The solar charge controller in that diagram is way undersized for the amount of PV you plan to use. Consider using two 100/50 solar charge controllers (at a minimum). Victron has a nice MPPT calculator you can use to figure out the exact solar charge controller you need.

With that much solar, I don't think you're going to need any charge from the tow vehicle. You can skip the DC-DC charger and especially don't use Renogy.

Yes, simple is good in my book.

I thought the solar charger looked small. Will figure out what to do for it when I finalize the solar panels I am using. Using two might be a good plan. Thanks for the link to the calc, that looks handy.

No plan to have a DC-DC due to the solar size I hope to have.

 

[RoadTurtle]

You're very close to what I'm currently finishing up.

I chose to run 6 panels, two SEPARATE strings on each side of the RV. So two SCC, instead of 1. This was to accommodate and deal with roof shadows. In terms of panel placement on the roof, as far outboard as you can get them to avoid shadows from the AC and vents on the roof.

400ah seems to be kind of a sweet spot to run light duty A/C power in the RV. Can't run AC or electric heat. 200ah didn't cut it for us.

I did go with 24v panels on a 12v system. There is apparently a slight advantage in less than ideal conditions to collect a little more energy.

I went with 12v batteries, because that is what I started with and didn't want to start over with expensive batteries. If I had to do it all over again, I'd probably go to 24v batteries. Now that I didn't follow my original plan for battery location, I might also look real hard at battleborn's 270ah battery. Their GC2 battery also lends itself to a buss bar instead of wires.

I chose to put the main cutoff switch between the battery and fuse for the reason you suggested.

 

[Chaucer]

Fuse before the switch is preferred.

@Zwy tks..but why? What makes it prefered?

It sort of makes sense to me to the switch before. If you want to turn power off to fuse to replace it..you have to disconnect the battery.

 

[RoadTurtle]

@Zwy tks..but why? What makes it prefered?

It sort of makes sense to me to the switch before. If you want to turn power off to fuse to replace it..you have to disconnect the battery.

if the switch is off, the battery wire leading to the switch is not protected by a fuse. I chose to take that risk and put the switch before the fuse.