12v and 110v and techquestions

[CheeseEater88]

Hello,

I have just started to look for my first RV travel trailer and I had a few questions.

First off I am am a bit of a tech lover. I do well with wiring diagrams and schematics, but I just can't find any details to what's inside of the new rvs I am looking at.

I am curios to the typical setup of travel trailers, I am currently really interested in the Venture RV 167vms, I like the pullout and the counter space. Dislike the skylights, and the TV mounting position(I can make a bracket to lower the TV). I assume its not common, maybe just a fluke, but the one I was looking at had wiring dangling free about 10" above the ground and the copper propane lines were looped lower than the rest of the frame


I digress, in my mind they have a 12v battery source, an inverter/charger, and a fuse box...then distribution out to the varied devices. My question I suppose would be what's actually there, and what runs on what? Are the slide out motors operated typically on AC or DC? The water pump? Ect..

Would it be easy to convert the system to 24v or 48v DC for the battery side of things? (it would make it easier to put lots of solar panels on) I can make a smaller loop or use a regulator to send 12v if needed to certain items. (I've been eyeing a 48v mppt/inverter/charger, as I wanted to possibly boondock, and stick crazy amounts of solar to the roof slowly over time...mppt is voltage and amperage limited based on the output voltage, so the higher voltage would allow me more pannels)

Again, I'm in the dark here, if someone with some first hand experience could give me a quick rundown on the typical travel trailer layout.

What ever I buy, I plan on keeping for a long long while, so I want to make it the best I can. That and I might full time in it off and on.

Thanks for all the help!

[CheeseEater88]

The 200amp is for the 12v battery to 110v inverter, if I use 24v then it's 100amp. If you put a load device on a circuit, you have to build that circuit out for it. It was really getting up there when I was thinking about 3000watts, 300amps isn't that fun.
If I put the inverter and the batteries under the bed in the pass through, I'm going to need SLA or lithium, or even NiMH but charging is an issue with other chemistries.

I could put the batteries on the tongue, where the original is loaded, but I'm scared about tongue weight. I can't just tap into the existing 12v system without doing some upgrades. The disconnects, some wires and terminal connectors will likely have to be replaced/added. I can run the inverter in parallel off the terminal, then feed a ground line to it as well. Leaving the batteries on the outside I could use the standard deep cycle.

In my mind it would be simpler to make a new circuit than to retrofit one to support an inverter. Like you said I won't know for sure until I get the thing. But it's good to have a well researched plan, I don't plan on doing this twice. I might very well go 12v with all the pressure on here.
I'm crossing my fingers for august or September.

As for the monocrystalline flexible cells, they are easy to just glue on your roof, and they can be found pretty cheap, they loose out to ridged panels because they can't be aimed.

[MrWizard]

we have 679w of solar on the roof, 675 ampHr battery bank (5) 135Ahr 105 lbs each, AGM high rate telco/server batteries
i like the idea of less weight of lithium
but the expense and the charge requirements, Do NOT warrant the expense and problems
our Triplite 1250 inverter will handle the 1600w input 1100 cooking watt MW, the coffee pot the vacuum , just about anything we need including our residential 120v fridge,

there is no reason (except i can and i want to) to install separate power and charger just for the inverter, and house 12v

i think you are over thinking some design details, that don't need to be what you think

solar for instance 80v at 6amps or 20v at 24amps 14ga wire versus 10ga wire
not a big deal
the truly large wire is in between the inverter and batteries
the cost of a few feet of one aught versus a few feet of 2ga, 12 vr 24 feet is less than the cost and all the trouble to install two different voltage DC voltage systems

you not doing high voltage 'grid tie"

[Harvey51]

You may be very pleasantly surprised at how well the 12 volt system works with just a little solar power. We never plug in or use a generator. After I installed a single 100 watt solar panel our batteries have never gone below 80 per cent charge.

I think adding solar a little at a time will serve you well. Do get a battery monitor so you can see how it is going and when your batteries approach the dreaded half charge where damage begins. Being handy and knowledgeable electrically, you will have no problem installing the $25 eBay battery monitor which shows amp hours and per cent charge.

[Almot]

CheeseEater88 wrote:

I wanted the separation of the two systems because I was going to use two disimilar batteries types SLA and a typical deep cycle., and I didn't want to deal with a 200amp setup and the safety of it.

Trying to make sense out of it.

12V and 110V systems are always separate, but this little to do with the fact that batteries are dissimilar. Besides, people change batteries from time to time.

200 amp setup - translation, please. There are no loads requiring 200 amps in a trailer.

Midnite Classic line-up isn't popular in RV. Planned/suggested 600W solar can be handled by TS MPPT 45 or 60. Better charging algorithm.

Flexible panels are rarely installed unless for very specific reasons which I haven't seen here mentioned yet. IMO, detailed planning of solar will not be possible until after you've bought the trailer. Somebody suggested to read more on 12V life, - I think this will be more productive use of your time, at this stage.

[CheeseEater88]

Mr. Wizard, I plan on financing it. I have no debt, and only some cash. My budget for everything is around $25k, the trailer is listed for 16k. Yeah I'm going to finance it, wish I could tell you I am independently wealthy.

Yeah I know there is a lot to matching lithium cells, and how one bad cell makes for a whole bad battery. I've only messed with a hybrid battery one time, and it was to basically test and replace all the bad cells with used cells from eBay that were a good match the cells in the pack. It's like a broad stroke, you end up buying a bunch of cells and hoping you get the 6 you need from the lot. Hybrid was in a Honda if I recall correctly, used sticks of D battery cells more or less. Dealerships will likely never take packs apart, it's very time intensive, even with automated charge testers, and batteries are almost a commodity.

I wanted the separation of the two systems because I was going to use two disimilar batteries types SLA and a typical deep cycle., and I didn't want to deal with a 200amp setup and the safety of it.

I've already talked myself down from a 3k watt inverter. At peak draw I assume I'd be a tick over 2000w. Some come with a 20sec surge rating of 6000watt. (makes me scratch my head).

I never said I was going to cover the fan/remove it, I just said I wanted to ditch the skylights, they use like a 3mm film of plastic. It was deforming in the little wind I have here. Sure overhead light is nice, but there are lots of windows on the left side, one on the back, and the fan in the bathroom is probably adequate enough in the daylight to let light through.

[Almot]

CheeseEater88 wrote:
all of the of the MPPT controllers I saw out there(till today) only allowed for 35v-85v open circuit voltage from the panels.

Low-current and low end models - yes. Check better models. My Rogue 30 has 100V limit. Morningstar MPPT 30/45/60 have 150V limit.

[Almot]

westend wrote:
I'd suggest that before you start acquiring anything, you do some sort of energy audit to estimate the amount of power you'll be using. Without any educated estimate of power use, the implementation may be either over-kill or lacking.

x2. With only only two comments - go big on solar, no matter what. You can't have too much of it. Eventually the solar size will be limited by roof real estate and plan, and here comes comment #2:

GO AND SEE YOUR DREAM TRAILER IN FLESH.
Step inside, open cabinets, check - sit/lay/walk around - kitchen, bedroom, toilet as if you were using it. Your pre-conceived ideas - about sunroof vents etc - could change then, same as your ideas about solar. Dark kitchen, short bed, impossible washroom - who knows what else...

[MrWizard]

At the OP
Have you looked for 24v lithium in the amount of amp hours you want
It has to be built as one pack with cell charge balance management for each cell
You can't just stick two 12v lithium in series like you do with less acid
They don't even work well paralleled
One pack pre built at the volts and amp hours

You seem to have the cash to do what you want, just need to be aware of what is feasible and what is not, you can't expand a lithium bank the way you do less acid
Amp hours voltage charger etc..
All installed as one system

Good luck

Any sla system you put in, will have to be removed and replaced if you go lithium, this includes the charger and battery bank

[Sam_Spade]

CheeseEater88 wrote:

and above for clarification I would have shore power, then in parallel have the 24v-> 110v inverter and the 12v systems charger feed from it,

You NEED to pay attention to what "westend" is trying to tell you.
I tried too but he said it much better and more completely.

Then.....what does the above mean ??
At times when you HAVE shore power, nothing else is necessary....or desirable.
And you should NOT have two 110 V sources connected in parallel, without a transfer switch, that is.

[westend]

I'd suggest that before you start acquiring anything, you do some sort of energy audit to estimate the amount of power you'll be using. Without any educated estimate of power use, the implementation may be either over-kill or lacking.

Also, unless a user is planning on continual days being fed from inverter, a 12V system is totally adequate. There is little benefit in increasing storage/charging voltage to 24V.

I'm also interested in why you need to have storage only for the solar charging and a separate bank for daily operations. Raising voltage with series connected modules just for the ease of wiring would seem incongruent. I think you would benefit from some additional study on system use and integration. Check out Jack Meyer's website for some practical knowledge.

[CheeseEater88]

hmmm... it doesn't like links... basically the list was:

6x 100 Watt Flexible Solar Panel with SunPower Solar Cells: SOL-100F-01 (I want to make sure they have diodes)
2x Duracell 12v 155AH SLA high rate batteries.
1x MidNite Solar Classic 200v MPPT Charge Controller

and the tool was Morningstar's string calculator, which is very nice.

pretty sure I will go with 24v to power the 110v inverter.

and above for clarification I would have shore power, then in parallel have the 24v-> 110v inverter and the 12v systems charger feed from it,

[CheeseEater88]

Let me make a short Summary of what I am looking at, and some of the tools I have come across while learning about PV systems.

So my list thus far:

(6x) ***Link Removed***

(2x) ***Link Removed*** (I was really hoping a solution like Schnider's Ecoblade was on the market, PV compatable and built in inverter and incremental 5 kwh of Li-Ion batteries in a very light system... but SLA will work)


(1x) ***Link Removed***


Still need a Inverter/charger/ UPS device. I really want to stay with a 24v setup...this system will be a completely separate system from the onboard 12v. Looking at >2000w with some surge capacity, hard wired 110v, UPS/quick transfer feature, charging, low power drain and a small form factor.

Then all the little safety devices like disconnects, fuses, and rated connectors etc.



I'm thinking Shore> 12v system charger > 24v or12v system- inverter/charger >110v

Figured when on shore, I'd have the 12v system charge, and the inverter for the 110v could feed from that as well, but when its disconnected it could power the 110v.



Some of the tools I've found are ***Link Removed***

midnight has one as well, but morning star has a large PV panel catalogue and multiple outcomes which makes it easier and faster to use than the others.

[CJW8]

Suggested reading: 12 Volt side of Life There is a part 2 that can be linked to from part 1.

[CA_Traveler]

brulaz wrote:
Consider partial shading of your panels.

AFAIK if one is in the shade, that will that reduce the output of all panels in series with it.

All my panels are in parallel.

Yes series/parallel panels have shade issues unless they are on multiple controllers.

I went with 3 series panels that have bypass diodes and are much more shade tolerant than parallel panels. If I added a 4th panel I would have to go series/parallel due to the 150V limit or use a second controller for the new panel. ie My panel Voc is about 36V.

[CA_Traveler]

The Morningstar MPPT 60 is 60A and 150V.

24V allows the CC to handle 2x the panel wattage and hence 2x the watts to the battery. But the panels must be double to provide the wattage. Or 4x for 48V.

There are only a few posters that have gone to 24V or 48V systems. Generally that will mean a 24V inverter and a DC to DC converter like a Vicron. The additional costs will add up.

Consider framed panels placed over the vents with enough clearance to open the vents. Less cost and more watts. Installed correctly wind will not be a issue.

Rarely can any A/C be run off of solar except for a small unit for a short period of time. An 8A A/C will draw 88A from 12V batteries. A/Cs just use to much power. Refer and HW are generally switched to propane. LED lights etc.