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Cinergi's 28 kWh / 4 kW Solar / 10 kW inverter RV build

cinergi

1.21 Jigawatts
Joined
Aug 9, 2020
Messages
1,419
Background
I'm having a new 5th wheel built and as part of that process, I'm designing and building the battery, inverter, and solar. I want to run as near as possible to 100% on solar for everything including A/C while boondocking (my new favorite activity). I live full-time in the RV (have been full-time for 2 years, RV'ing for 3). Since this is a custom build RV, I'm able to do things like tell them to keep the roof 100% clear of obstructions for maximum panel density.

The RV
2021 New Horizons Majestic 5th wheel - 37 feet. I'm modeling the floor plan after this 40 foot design: https://horizonsrv.com/custom-rvs/majestic/40-ft-majestic-m40rk4s/
The batteries and all equipment (below) will live in the heated basement (I'll rarely be in cold enough weather to worry about that -- rather, I'm worried about heat buildup. I'm currently working with them to design a way to thermostatically vent the basement as I suspect it will run hotter than I want).

System Specs
  • 4+ kW solar (TBD)
  • Victron SCC's (TBD)
  • 2 5k Victron Quattro operating in split-phase
  • 28 kWh of battery (2 14 kWh batteries - each made up of 16 280Ah EVE cells from Shenzhen Basen via group buy here)
    • 2 Chargery BMS16t's with 300A DCC
    • Custom built battery box (similar to others I've found here) - mostly for compression and a place to mount BMS and battery posts
  • 30k LG Mini-split (LMU30CHV) and 2 zones (9 and/or 12k each)

I've received 7 of the 9 boxes (I ordered 36 cells, so I'd have 4 spare on hand). The other two are due tomorrow and Friday.
Victron order was just placed and should be here inside a week.
Cables and other stuff I just ordered and will arrive throughout the next week or so.

I'm currently sitting in my to-be-sold RV in my parent's driveway ("mooch-docking") and using their basement as my lab / build area. I'll get everything built and tested etc before I bring it to Kansas to install in the RV when I pick it up sometime in February. Logistics are totally up in the air at this point - but that's the general idea.

Right now, I'm toying with how I'll connect everything to the cells. That's the next post which I'll do in a few minutes.
 
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Here are the 7 boxes so far

image3.jpegimage1.jpegimage5.jpegimage4.jpegimage2.jpeg

There are different bar codes between the 4 cells I pulled out of the boxes so far. I hope that doesn't make a difference. After I get all 9 boxes, I'll do my best to match up the 2 groups of 16 cells.

As for connections, I've determined through trial-and-error (error being the key word) on other 100Ah cells that I'll use a stud / grub screw (headless bolt) and lock that into place using high-strength (red) Permatex brand thread-locker.

I'll use 1000-grit sandpaper on everything as well as anti-ox cleaner before assembly. Using the 3 strategies of 1) studs, 2) sandpaper, 3) anti-ox, I couldn't believe the difference it made in the 100Ah test build. There was no change in inter-cell voltage at rest vs. under load even at .5C.

As such, I'll replicate that, as well as being what's probably overkill on connecting stuff to the cells. So, "version 2" of my connection might look like this:

image0.jpeg

Where I have a connection (lug or bus bar) followed by an oversized SS washer (that's the same diameter as the cell terminal), followed by the BMS lead, a smaller washer, a lock washer, and a non-serrated flange nut. I'm thinking this will give me the widest & most even distribution of pressure down onto the connecting meeting the cell terminal. At only 7 Nm of torque, this may be overkill, but I wanted something strong (extra-large SS washer) to distribute the force down onto the softer metals as evenly as possible without scoring anything in the process. Note that the lug in the picture is a test lug - not the final lug (to be received) that I'll be using.
 
Current electrical diagram:
NH%20Electrical%20V3.png


The 12v loads can be quite high (e.g. hydraulic jacks or slides), hence the need for the "buffer battery" ... the 48/12 Orion only does 30 amps and I don't feel like stacking 4 of them.

I also need to update the diagram a bit to show that single-phase input (e.g. 30/20/15 amp shore power) will go into AC2 on the master unit. AC1 can only take 240v split-phase. When I need to connect to single-phase, I'll have to use a different connection and reconfigure the Quattro's. Not great, but should be rare.
 
Looks good. Why do you think single-phase will be rare? It's super common in a lot of the most interesting places.
 
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Looks good. Why do you think single-phase will be rare? It's super common in a lot of the most interesting places.

Thanks!

Most of the places I have been to had 50 amp service available. I'll generally either be on 50 amp or boondocking. In 2 years, I've only been forced to run on 30 amp once. I'm more likely to be limited by the fact that I'm 37 feet (plus the truck) in terms of which parks I can go to :)
 
Thanks!

Most of the places I have been to had 50 amp service available. I'll generally either be on 50 amp or boondocking. In 2 years, I've only been forced to run on 30 amp once. I'm more likely to be limited by the fact that I'm 37 feet (plus the truck) in terms of which parks I can go to :)

We find that many older parks, state parks, and all moochdocking is on 120V supply. Of course there are plenty of places to stay with 240V, but casually estimating, I would guess >30% of all parks are not upgraded. Many of those are decrepit and undesirable places to stay, but of course some of them are otherwise true gems.

Having to reprogram to break the split phase config is a huge bummer. It means a total power drop, which is a no-go in our rig with the computers and other machines that maintain state.
 
We find that many older parks, state parks, and all moochdocking is on 120V supply. Of course there are plenty of places to stay with 240V, but casually estimating, I would guess >30% of all parks are not upgraded. Many of those are decrepit and undesirable places to stay, but of course some of them are otherwise true gems.

Having to reprogram to break the split phase config is a huge bummer. It means a total power drop, which is a no-go in our rig with the computers and other machines that maintain state.

Yeah not ideal .. but I tend not to gravitate towards those parks anyway ... and I'd only need to do it if my solar can't keep up (e.g. under trees). I'm gonna have at least 4 if not 4.7 kW on the roof so ... but I hear ya.. I've been trying like mad to design something that'll work for both and I've even enlisted Victron's help ... this is the best we can come up with :(
 
Yeah not ideal .. but I tend not to gravitate towards those parks anyway ... and I'd only need to do it if my solar can't keep up (e.g. under trees). I'm gonna have at least 4 if not 4.7 kW on the roof so ... but I hear ya.. I've been trying like mad to design something that'll work for both and I've even enlisted Victron's help ... this is the best we can come up with :(

Yeah, I think the only way to do it without a reboot today is to add more hardware (most likely a transformer).
 
Yeah, I think the only way to do it without a reboot today is to add more hardware (most likely a transformer).
That was my V2 but because the minimum amperage at 240 is 13.5 I'd need 27+ amp minimum at 120 which MIGHT work on a 30 amp circuit and obviously not on the 20 and 15 amp circuits ... Not to mention what to do about a generator ...
 
That was my V2 but because the minimum amperage at 240 is 13.5 I'd need 27+ amp minimum at 120 which MIGHT work on a 30 amp circuit and obviously not on the 20 and 15 amp circuits ... Not to mention what to do about a generator ...

Yeah, shore mins will get you going in that direction.

But perhaps you could just do a stepup on the output side of one of the two 120V inverters, for your mini-split? (I'm assuming your RV doesn't have any OEM 240V circuits.) Then you could run the two inverters in parallel, rather than split phase, and then you can control charging per inverter.
 
One other possibility is just a standalone 120/48 charger...

Yes, I went this route with a dedicated 120V charger.

One interesting option is Meanwell HLG-600H-54. You can stack several of these at ~500W apiece and essentially achieve whatever custom load you need on the fly. They don't have the charge algorithms, but you don't need it if you set their CV value low enough and are willing to accept never reaching 100% SOC from the shore supply in that scenario. They're not too expensive, either.

I actually use a 120V Quattro as a dedicated charger, which is the expensive route, but I had my reasons at the time. :) I also have two of the Meanwells so that I can use a 30A and a 20A outlet where that is provided -- but that scenario is rare, indeed.
 
Yeah, shore mins will get you going in that direction.

But perhaps you could just do a stepup on the output side of one of the two 120V inverters, for your mini-split? (I'm assuming your RV doesn't have any OEM 240V circuits.) Then you could run the two inverters in parallel, rather than split phase, and then you can control charging per inverter.

The minisplit (240) is OEM but I believe the only 240v appliance... That's an interesting thought .. just parallel at 120 and create a dedicated stepped-up circuit for the minisplit.. but then I'd lose 240 input for charging, no? I haven't researched that...

From what I understand I have to change the Victron "switch as group" setting ... that requires a power interrupt?

The separate, stacking chargers make sense ... turn on as many as makes sense for the available power ... and it means I can use a portable generator if I'm boondocking and the sun isn't keeping up. I'm avoiding the built-in propane 6.5 kw 240 generator cuz it's $8300 yikes!
 
As a side note, I'd love to come up with a fully-RV-friendly system because I think I could get New Horizons to integrate it as one of their own electrical options. As it stands, I'll rip out their basic system and install mine because they're not willing to go this far.
 
You'd lose the 240 for charging, but in practice it's not quite that bad. Each Quattro 5kVA can only charge at 70A, or about 3500W. If both are connected to a single leg of the 240V, you have 50A (42A continuous) available. So you can still charge at 5kW continuous... a little less than your nameplate capacity, but honestly I can't get my big Victron chargers to run at nameplate for more than a few minutes anyway. They derate for heat.

So I think the practical charging consequence is somewhat minimal in your specific config.
 
One more of the 9 boxes received. Doesn't have the bus bars argh! 9th box is now scheduled for Monday :(

I've unboxed the 32 cells I've received so far. Boxes and packaging and cells are in excellent condition. Excellent packaging.

One oddity - this cell's bar code is damaged:

image1 (1).jpeg

There are 3 different sets of bar codes I've received so far. I was able to group one set of codes into a 16-cell arrangement. Another 13-cell arrangement, and 3 "left over" ... hopefully the 9th box lets me complete the 13-cell arranagement.

image0 (1).jpeg

Every cell is marked as the same voltage and IR... which seems nearly impossible but .. *shrug*

This weekend is about building the battery boxes (plywood, threaded rod, etc).
 
my plan is basically a mini-version of yours. 1997 diesel pusher MH, I am using 32x 120ah cells (I have 48), chargery 8t's, and am strongly considering victron inverters

I replaced my progressive 12v80a charger with a mpp-style AiO 12v inverter/mppt controller/ 20a grid charger.

I went with a harbor freight 3500w inverter generator.

currently looking for a building to rent that's tall enough for me to re-roof the rig. anywhere I can't fit big panels (I have 25 250w 60cell panels) I will squeeze smaller panels on the 12v system.
 
I saw your mention of the bus bars and screws not being in boxes.
I the orders I received had bus bars for several boxes all in one box.
 
I saw your mention of the bus bars and screws not being in boxes.
I the orders I received had bus bars for several boxes all in one box.

Yeah I'm making the good-faith assumption that this is true... just getting really unlucky that it's the LAST of 9 boxes over the course of 6 days lol
 
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