Finishing up my design for my 1200w RV build

[willo]

Welp, I finally wired in my multiplus! I used Tom Morton's wiring idea for a contact switch. The switch disconnects shore power and bridges L1 and L2 for the multiplus to feed. I ended up buying 6/3 wire at HD and extending the main shore feed over to my battery bay, and a return run to feed from either shore or the inverter. I even managed to run an A/C in testing, but will be adding soft starts in the near future.
I need to finish up wiring the shore to inverter feed, but decided to get a couple more cuts of 6 gauge from HD rather than cut up the remainder of my 6/3 that I can use for other things.

So the inverter use cases that this will support:

• Stand alone - all solar
• Hybrid - add inverted power to shore/generator power - L1 and L2 bridged to the box but NOT toward shore - shore can be 50a but it'll only use one leg to power the inverter.
• Full shore power - inverter bypass, shore power goes directly to the panel like the factory intended.

The inverter/charger will always get power from the shore wiring. The ability to disconnect the inverter output from the internal breaker isn't a requirement but it's actually a nice feature.
In the end, I can create 12 volts from either my 24/12 converter or turn on my power converter in a pinch. In general I just leave it turned off but in the event hardware failure I can give up efficiency as needed. Heck, sometimes I turn on the power converter to let the battery bank charge faster off solar.

 

[HaldorEE]

Welp, I finally wired in my multiplus! I used Tom Morton's wiring idea for a contact switch. The switch disconnects shore power and bridges L1 and L2 for the multiplus to feed. I ended up buying 6/3 wire at HD and extending the main shore feed over to my battery bay, and a return run to feed from either shore or the inverter. I even managed to run an A/C in testing, but will be adding soft starts in the near future.
I need to finish up wiring the shore to inverter feed, but decided to get a couple more cuts of 6 gauge from HD rather than cut up the remainder of my 6/3 that I can use for other things.

So the inverter use cases that this will support:

• Stand alone - all solar
• Hybrid - add inverted power to shore/generator power - L1 and L2 bridged to the box but NOT toward shore - shore can be 50a but it'll only use one leg to power the inverter.
• Full shore power - inverter bypass, shore power goes directly to the panel like the factory intended.

The inverter/charger will always get power from the shore wiring. The ability to disconnect the inverter output from the internal breaker isn't a requirement but it's actually a nice feature.
In the end, I can create 12 volts from either my 24/12 converter or turn on my power converter in a pinch. In general I just leave it turned off but in the event hardware failure I can give up efficiency as needed. Heck, sometimes I turn on the power converter to let the battery bank charge faster off solar.

Got a link to Tom Morton's idea?

 

[willo]

Diagram is https://mortonsonthemove.com/wp-con...phase-3-the-inverter/solar-phase-3-1_orig.png
Page about it is https://mortonsonthemove.com/solar-phase-3-the-inverter/

 

[HaldorEE]

The Multiplus includes an intelligent automatic transfer switch. What is the point of adding a manual transfer switch between the Multiplus and shore power?

 

[willo]

The Multiplus includes an intelligent automatic transfer switch. What is the point of adding a manual transfer switch between the Multiplus and shore power?

My 50a rv has two legs, l1 and l2. The switch combines them to be a single leg from the multiplus. When I'm on shore power and want full feeds the switch let's me. There is an automatic switch made but Its pricy enough that I'd just buy another multiplus over that.

 

[snoobler]

Nice. And that also allows multiplus battery charging while on shore power.

 

[HaldorEE]

My 50a rv has two legs, l1 and l2. The switch combines them to be a single leg from the multiplus. When I'm on shore power and want full feeds the switch let's me. There is an automatic switch made but Its pricy enough that I'd just buy another multiplus over that.

Do you actually need both legs of shore power to operate your RV? That is 6900 W.

 

[snoobler]

Most 50A RVs have a lot of power hungry stuff... 2 A/C units, an absorption fridge on electric and an electric water heater, microwave. That's 6000W or so right there not counting surge or any 12V power usage. When on shore power, you get to use the juice all willy-nilly-like.

 

[HaldorEE]

If you get a second Multiplus they will handle split phase power in and out without an external transfer switch.

I don't see the point of adding this.

 

[snoobler]

Transfer switch is a lot cheaper than a second multiplus, and that's not counting the cost of a larger bank to feed them and the presumed additional consumption...

On an inverter, you pay attention. On shore power, you turn everything on because you can.

 

[HaldorEE]

Most 50A RVs have a lot of power hungry stuff... 2 A/C units, and absorption fridge on electric and an electric water heater. That's 4500W or so right there not counting surge or any 12V power usage.

Ok. Do 50A RVs use 230 or do they just have 2 banks of 120V breakers?

I would just use a pair of 3000W Multiplus inverters in a split phase configuration it it was my system.

 

[snoobler]

2 banks of 120V breakers. That's why you can short L1 and L2 and power the whole RV. Nothing actually uses 240V, but the A/C units are typically on different legs to help level the load.

 

[willo]

Ok. Do 50A RVs use 230 or do they just have 2 banks of 120V breakers?

I would just use a pair of 3000W Multiplus inverters in a split phase configuration it it was my system.

Yup, if I want more it's getting a second multiplus. For $30 I'll deal with having the switch for a while.

 

[Gould]

Resurrecting because I’m planning the same install. What I can’t wrap my head around is the risk. Is there a scenario you have to be cautious of - like what happens if you’re in the position that bridges the legs and you connect to a 40 amp service?

 

[willo]

My combiner switch has a couple of modes.
1. each leg works normally but the multiplus is inline on one leg.
2. Both legs of the panel are bridged and fed from the multiplus. Only one leg from shore power is connected to the multiplus. The second is disconnected.

To be clear, the multiplus is always connected to one leg of shore power, the switch just connects the second leg of the panel to either the multiplus or shore power.

I can easily add a second multiplus and would just eliminate the switch.

 

[snoobler]

30A is 120VAC, L N and G only
50A is 240VAC split phase, L1, L2, N and G.

A 30-50A adapter that allows a 50A umbilical to plug into 30A service bridges L1 and L2, so at the RV AC panel, L1 and L2 are zero to each other but 120V to neutral.

When plugged into 50A service, L1 and L2 are 240VAC to each other and each are 120VAC to N.

If your RV is configured to bridge L1 and L2 to work via a 120VAC source, if you plug into 50A, you'll short L1 and L2 at the 50A outlet and trip the breaker.

If your off-grid system is providing 120/240VAC split phase, it likely needs 50A service and won't work from 30A service.

If you're using transfer switches, you can get around most obstacles.

 

[willo]

Just to link things together a bit.
I've now replaced the old Tesla pack with the LifePO4 pack.
Battery order was:

Ordering 16x 280Ah cells from Shenzhen Luyuan

OK, if Alibaba ever processes my card - I specifically used a CC in case of disputes, etc, than I've gone for the following: 16x 280Ah cells. https://www.alibaba.com/product-detail/3-2V-280Ah-Lithium-Ion-Battery_62585177205.html Which ended up at $1660 + a $48.97 processing fee for a total of...

diysolarforum.com

Wrote up a bit about the RPi and monitoring here:

RPi Internet and Victron Monitoring

Got a request for info, so I figured I'd bring this over here. I use a bunch of victron bits in my RV now and have added a raspberry pi running the victron venus image and I have a second pi that rocks a 4g card to provide internets. First up, the Internet Pi: This is a Pi 3+ that has a sixfab...

diysolarforum.com

Documented the battery build here:

Battery Box Build

So I'm just planning out my battery box builds for the new pack. After doing some winter camping with a crappy shore feed, I knew I had to add some battery heating for the new build. My batteries live in the unheated compartment of my 5th wheel camper.... The Batteries: 16x 280ah Lifepo4 cells...

diysolarforum.com

Eyeballed my PV layout and pondered more cells:

My PV Layout. 37ft 5th wheel, and considering some upgrades.

I grabbed some footage of my PV layout the other day. Figured I'd share. Right now, I'm using 12 100w rich solar poly panels (yeah, the ones reviewed by Wil in one of his comparison vids) As you can see, the main line of 9, fits really nicely, although that antenna can cause shading. I should...

diysolarforum.com

Installed the new SBMS0, new rev, and I printed a custom mounting box for it:

SBMS0 v03d mount SBMS0 by willoco

45 degree mount to hold the (now) current SMBS0 V03d. Designed for my RV solar install. This one is completely usable, but never perfect. :) Screw holes were made for random hardware I had laying around. Tune as required. I ended up mounting this on a bulkhead instead of my battery box, so I...

www.thingiverse.com

Did some analysis with my Flir Camera:

Thermal Data - Fun with my Flir.

After this weekends upgrades, I need to do a little bit of wiring cleanup. Before I really dig into that, I wanted to evaluate how things are working. It's been a beautiful day, about 70 outside. I ran one of my A/C units for about an hour just to really give things a chance to heat up.... and...

diysolarforum.com

Meanwhile I'm still slowly working on my controller integration:

Smart Battery Heating.. and more

So I'm part way through building my new battery packs, including RV water tank heating pads and insulation. I'm going to build a heat controller to run the heating pads, and am just starting to rough out the logic. After some consideration, I think that I'll end up building a full on power/data...

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