New Inverter time... Multiplus or something else?

[willo]

Just a reality check...

My camper has 1200 watts of panels, a Victron smartsolar controller and a tesla battery module. (I'm probably moving that to Lifepo4 soon but I scored the tesla and it works) Victron BMV712, smart sense and 24/12 converter. I'm happy with Victron, it works and gives me all the nerd factor I want.

My RV takes 50 amp electrical service. I've successfully run both A/Cs and the microwave off of a 30 amp circuit at one RV park, which was surprising. So, if I target that load level, I'm really going to want around 3200Kw of inversion.
I used a cheap 3kw inverter this summer, and it was handy but frustrating. The cooling fan was really loud and I found that I required a soft start on the A/C to actually run it. The surge on startup was too much for the cheapy inverter.
To use a single phase 30 amp circuit, I used an adapter cable the bridges L1 and L2 phases at the power connector. I have same in a 15amp cable.
To use the inverter, I ran a cord from the front of the camper, to the back where the power connector was. This worked but was janky and annoying.

After summer travels, I see my usage and requirements of this going a few ways.

• Run a single A/C off solar all day while I'm in transit to keep the camper cooler inside - It can take some time to cool off after towing for 8 hours in 90 degree+ weather.
• Run at least one A/C all day when I'm at the beach, with the option to run two when needed.
• Use the inverter hybrid to prevent killing power when I have a 15 amp circuit.
• Power the fridge to save on propane while driving
• Full power when boondocking.
• No external wiring. One moron thought I was camping in the street when I was visiting my father and had it plugged in.
• Don't care if I can run laundry off solar... It uses a crap ton of water, but it'd be nice as well. (I have a combo that runs off a 15a circuit.)

So I have some items to solve.
I see the Multiplus 24/3000/120 as a good solution... but I kinda want a pair. At $1200 each, that's gonna hurt a little. I'd use a pair of 2kw inverters but that'll save like $100. I'm not even sure why they bother to offer the 24/2000/120 version considering the price. I like that the multiplus has built in transfer switching, but only for one phase... Thus wanting a pair to run in parallel, one for each leg of the AC panel. Oddly the 5000w units are nearly 2k, so I see dual 3ks being the way to go.

I could wire up a diy transfer switch, get a second cheap inverter and add soft starts. This would get me there. I feel like it would also affect the resale value of my camper. (Which is an issue when talking about a unit like mine.)

So, do I go with a multiplus or should I be considering something else? I honestly just haven't seen anything else that comes close in features.

 

[snoobler]

Magnesine MS4024PAE is a good option with 120V or 240V split phase to feed your 50A input.

 

[willo]

Hmm, reviewing the docs on that:
WARNING: DO NOT connect 120 VAC (same phase) to both AC HOT 1 IN and AC HOT 2 IN inputs. These inputs must be 180° out-of-phase (i.e., 120/240 VAC). If you only have a 120 VAC source, you may connect to either the AC HOT 1 IN or AC HOT 2 IN, but NOT to both or damage may occur.
This would be bad in the case of a single phase shore power input.

 

[snoobler]

Not sure I follow you. It's just telling you not to be stupid and connect a single phase source hot to both hot1 and hot2.

Shore power, like a 50A RV plug, is split phase 240V and the hots are 180° out-of-phase. 30A is single phase and only has a Hot, N and G.

Also, your requirements for running A/C may not be realistic. We have 3kW of solar and we can only one 1 unit for 8-10 hours before we dip into the battery. Their typical consumption is 1400-1500W.

1200W of solar is barely a start. You can run one unit for maybe 4 hours assuming nothing else.

You will need MUCH more solar and a metric crap-ton of batteries you will need to charge via shore power in order to have any chance of running the A/C as you indicate.

 

[willo]

Some shore power is only single phase. The adapter for plugging in the feed combines both feeds to the one phase.

 

[Rocketman]

For switching between 50Amp Service and 30Amp Service I found a Youtube video that I am thinking about using the manual switch - Channel "All about RV's" episode "RV Inverter setup! How to power 50A and 30A". Basically you use a 50A switch to have your rig either use the inverter on both legs or in 50A mode - one leg to the inverter - the other to the other leg direct shore power.

If you are thinking about 2 3000W inverters - go with the 5000W instead. Simpler.

I have a 3000W Multiplus in my MotorHome and I LOVE it! (just wish I had lithium batteries - someday soon ).

I have been doing the math for a future system. If I just want to run one A/C I only need a MultiPlus 3000. If I want to run both A/C's, then I need a 5000W (Multiplus or Quattro + a massive Lithium Battery).

I think with one Tesla battery it can handle one A/C (with OK run-times), but to run two - will probably need an additional battery.

One other thing to think about - it may make sense to go to 48v (two batteries in series) vs the 24v. - that would make running the 2 A/C's easier.

Good Luck!

 

[snoobler]

Some shore power is only single phase. The adapter for plugging in the feed combines both feeds to the one phase.

Are you saying some shore power is single phase 240V? I've not encountered that, and I would be VERY surprised if that exists. NEMA 14-50R plugs have a specific wiring, and it's not single phase.

If you're talking about the 30A to 50A adapter, you'd make your own that doesn't jumper L1 to L2.

 

[willo]

Are you saying some shore power is single phase 240V? I've not encountered that, and I would be VERY surprised if that exists. NEMA 14-50R plugs have a specific wiring, and it's not single phase.

If you're talking about the 30A to 50A adapter, you'd make your own that doesn't jumper L1 to L2.

Yes, I'm referring to standard 30A to 50A and even my 15A to 50A adapters. I have both and use both. Those adapters feed both hots of a 50a feed from a single phase input. A custom adapter is an option, but it's a terrible idea.
If someone else was using my camper and had to buy a replacement adapter while traveling, this becomes a safety hazard.
Heck, I'd be annoyed if I had to wire up a new adapter on the road after losing one. I can guarantee the wife wouldn't be happy.
Better to be able to get a replacement adapter at any store.
Some campgrounds may have questionable power that may not be wired correctly. Better to properly wire and not take the risk.

After looking at this issue a bit more, I think the solution is to install a changeover switch: (Credit to Mortons on the Move for the idea)

https://www.amazon.com/Baomain-Universal-Changeover-SZW26-63-Position

Not sure if I'd buy that specific one, but it's functionally what's needed.
With this, I get three settings: 0, 1, 2.

• 1: 50A shore power mode: Feed L1 from shore power, Feed L2 from shore/inverter power.
• 2: Full inverter mode: Combine both L1 and L2 phases on the panel and Inverter pulls single phase (no matter what adapter/input is in use) Inverter can still pull shore power.
• 0: All connections disconnected.

If you have an inverter that doesn't support hybrid/grid mode, then you could just wire up one selection to feed Both legs from the inverter OR select shore power. In my case with a Victron, the above is the way to go. Either way, it'd be safe and allow use of any input adapter off the shelf.

 

[willo]

OK, so I looked as several options. I just didn't find a dual phase that really suits the RV installation. (IMO)
I did consider the Magnesine. At $1600ish for a 4k inverter, it's attractive.
It would support dual phase, but there is a risk created if I wanted to support dual phase and single phase input - forget to flip the switch and you've killed something. If you've driven all day, you're very likely to do something stupid. Bad wiring at a camp site... boom.

In my opinion, the best choice is to use a single phase 120v inverter. Many of these can run in parallel for additioinal capacity. I personally am very happy with Victron equipment, and decided to give in and get the victron Multiplus 24/3000. It's really enough power to get started AND it'll combine well with my other Victron gear. I am very happy with the victron app...

In the future, if I want more capacity - say dual A/C power, then I'll add a second Multiplus 24/3000. I compared pricing for 5000 watt inverters and really it's cheaper to run dual 3ks and I'd have some redundancy.

 

[snoobler]

I'm a Victron fanboi with 2X 5k Quattro/48, so I can't fault you one bit. I missed the number of times you mentioned Victron in your initial post. We could have avoided this whole tangent...

 

[willo]

Meh it's always good to review and discuss! The conversation helped me firm up my sentient tapioca.

 

[snoobler]

LOL... sentient tapioca. I'll have to remember that. Though cerebral flatulence is often the norm with me and it will fall right out.

 

[creeky]

New here. I'll say Multiplus. Your cheapy inverter is probably going to rattle itself to death soon. Some of them are built pretty good, but but. If you're thinking lithium battery pack. Maybe wait and do a 48v lithium pack with a Quattro? Interesting to see how everyone copes with 240 split phase. Maybe we should get smart and just switch to 220/50hz like almost everyone else in the world. Boy wouldn't that be nice. All those amazing inverter/chargers to play with.

 

[willo]

I have 1200 watts in panels feeding a 5kw tesla module. I may change to lifepo4 but I'm running 24v to handle the solar load and down convert that to 12v for house systems.
Tesla likes lower voltages than the average 24 but it works. The new inverter will allow trivial battery changes to lifepo4 when I'm ready.

 

[JoeHam]

I’m late to the party here but let me add the Schneider Conext SW 4048.

It can output 120v or 240v. I have mine feeding a critical loads panel with 240v.

Most notably it has an autotransformer built in. This is an option on the Victron unit that costs an additional nearly $600.

What that offers me is the possibility of feeding my CSW 4048 with 120v from a genset or grid and it will output the 240v to my critical loads panel.

This would only be necessary if my solar/battery and grid went down at the same time but it’s a nice option to have.

Also available in a 24v version.

 

[cinergi]

A dual victron quattro can accept either split-phase 240 in or 120 single-phase in and still produce 240 split-phase out. To do this, connect the single-phase 120v input to the master inverter. Connect nothing to the second inverter. I was hoping the secondary unit would be smart enough to see that it's getting the same leg as the first and just ignore it, but maybe not... so in that case, I, like you, will need a special dogbone adapter that only connects one of the 50 amp legs of the plug to the single-phase input and put warnings somewhere appropriate to not use a special adapter. I'm sure there's an automatic way to make this happen so that one can't destroy their victrons by using a normal dogbone adapter.

(because in a two-inverter split-phase setup, you connect line 1 to unit 1 and line 2 to unit 2)

 

[willo]

I did consider Schneider units, but I don't have a good feeling on them for mobile - aka trailer mounted. I've seen several victrons in mobile installs but not much in the way of camper/mobile reviews. I certainly use plenty of APC products but I just don't see lots of date points.
(Again, this is my opinion)
I did take a look at the quattro, but for the cost... it's just silly unless you have space issues. My electrical bay is huge so I don't care.
But..
one 24v 5000w quattro runs 2825.
one 24v 3000w multiplus runs 1285, two would be 2570 and yield 6kw of inversion.
I am ignoring the wiring, but I'll be lazy and call wiring costs equivalent.

In all fairness, I don't care about actual split phase other than it is how they run 50A in an RV.
Oh... and ironically they put both of my A/C units on the same phase. I'm amazed I didn't pop breakers all summer.