Victron MultiPlus II Inverter/Charger

[Zulu]

I'm looking into installing an inverter/charger in my RV. I've done this twice before in my other RVs using a Xantrex RS2000 and a Magnum MS2000. Both of these inverters have 30A internal transfer switches, so you needed to install a sub panel for multiple AC outlets. PITA.

However, on first blush I think the Victron MultiPlus II has a 50A internal transfer switch with both L1 & L2 outputs.

If so, doesn't this mean that the Victron could be wire right into my RV's 50A main panel with no need for a separate sub panel?

Edited January 8, 2022 by Zulu

[Zulu]

4 hours ago, Zulu said:

If so, doesn't this mean that the Victron could be wire right into my RV's 50A main panel with no need for a separate sub panel?

Yep. Here's the poop.

[Chad Heiser]

Yes, the Multiplus II was designed specifically for 50 amp RV’s in the American market.  It can be wired in ahead of the 50 amp power panel in an RV and power all the circuits with either pass through shore power or from the inverter (obviously only up to its power generation capabilities when inverting).  I have installed several of them and it makes the installation process fairly simple.  The user does have to pay attention to what they turn on in the RV when running on inverter power so you don’t overload the inverter or drain your batteries too quickly.

The inverter will pass through both legs of a 50 amp power pedestal, but it does not invert on both legs independently though.  When inverting, the inverter combines L1 and L2 internally similar to how a 50 amp to 30 amp dog bone connector works when plugging into a 30 amp power pedestal.

[oldjohnt]

Unlike Chad, I have NOT installed one so can only speak from related experience, so FWIW here are my inputs.

 I have seen and used sub panels and transfer switch arrangements for selective and/or limited Inverter versus shore power use and I have seen and used simple Inverter feeds by placing inverter fed receptacles in certain critical locations where the load is simply unplugged (from utility) and re plugged to Inverter fed receptacles (no Transfer no Sub panels) that's so easy cheap and simple.

 HOWEVER I agree with Chad if you can get by with NO transfer switching and NO sub panels NOW THATS THE WAY TO GO......and if I were to install one that would be my choice.. 

 In a perfect world my preference would be if a 50 Amp Inverter produced the same true 120/240 Volt Single Phase Three Wire service as the utility versus acting as a dog bone L1 L2 combiner, but hey as long as it works and fills your energy needs  NO PROBLEM and it's widely in use just fine ?? Then there's the question if a 240 volt dryer or other appliance (even if not typical) is used ??

Thanks Chad, your expertise and experience is a Godsend to this Forum, I appreciate and learn from it yayyyyyyyyy

John T  NOT any solar expert but never too old to learn I hope

Edited January 8, 2022 by oldjohnt

[GlennWest]

You also have the choice of a 240v unit and use an autotransformer. Now a plus to use the autotransformer. It will compensate for out of balance loads within limits

[Zulu]

8 hours ago, Chad Heiser said:

Yes, the Multiplus II was designed specifically for 50 amp RV’s in the American market.

Sweet! and it's actually less expensive than the Magnum I was looking at.

Chad, I hope you don't mind me asking you some more questions in the days to come.

[Chad Heiser]

On 1/8/2022 at 9:22 AM, Zulu said:

Sweet! and it's actually less expensive than the Magnum I was looking at.

Chad, I hope you don't mind me asking you some more questions in the days to come.

Not at all.  I’m happy to help.

[Zulu]

On 1/10/2022 at 12:12 AM, Chad Heiser said:

Not at all.  I’m happy to help.

Alrighty . . .

I'm planning on adding solar panels, additional house batteries, and an inverter/charger to my RV, but not all at once. To much $$$.

So, I figure adding solar panels will come first since it provides some off-grid freedom.

Also, since solar systems can be no cheap date, I'd like a system that's as "upgradeable" as possible. In the past I started with a minimal solar system then found myself upgrading PV panels, charge controller, wiring, . . . There was a lot of wasted time and money.

I plan to start with a 2-panel 730W system that would be "easily" upgraded to a 1095W system.

When I saw your 2-panel Cougar 26RBSWE installation, it looked like a great base system. Also, since I think it's based on Northern Arizona Wind & Sun's 730W Solar Kit, it made for a convenient install since all the system parts are in one kit.

However, I'd like to modify the 730W kit so I can "easily" add that 3rd PV panel at a later date.

If you could check out my wiring diagram, it would be a great help . . .

Northern Arizona's 730W Solar Kit Wiring Diagram

Northern Arizona's 1095W Solar Kit Wiring Diagram

My Upgradeable 730W Solar Wiring Diagram

 

[Chad Heiser]

Northern AZ's diagrams are fine.  Although, I prefer the the Midnite Solar Baby Box with MNEPV breakers over the DC Circuit Breaker set up.  I put Midnite Solar Baby Boxes with MNEPV breakers (appropriately sized) in all my solar installs now.  They act as both circuit protection and shutoffs.  The MNEPV breakers are directional in a DC circuit.  They come labeled with a + on one side of the breaker and a - on the other side of the breaker.  The + side of the breaker always connects to the highest potential of energy.  On the battery circuit, that would be the battery side.  On the PV circuit, that would be the panel side.

I don't know if you just missed it in your diagram, but you want 4 AWG wire on both sides of the Baby Box for the battery side of the circuit. You also want 4 AWG lugs instead of the 6 AWG lugs in the parts list (#14) to go with the upgraded wire size.

I would also change to the proper rated circuit breaker for the MPPT 150/70 (at least a 70 amp, but more likely an 80 amp instead of the 60 amp in your parts list).  You are sizing the breaker for the wire (4 AWG) and the output of the solar controller.

I install 365 watt REC panels often.  (I have a large number of them on hand).  They are large panels (approximately 40" x 80").  I always install six panel mounts (z-brackets) per panel (three on each of the long sides).  The panels will flex too much with just four mounts on an RV.  If the panels are going to be mounted perpendicular to the roof, then the brackets will need to be adjustable to help compensate for the typical curvature of an RV roof.  If they are going to be mounted parallel to the roof, then this is not a concern.  Also, because of their physical size, it may be difficult to keep the panels close enough to one another to connect them in series with just the pigtail connectors that come on the panels.  It depends on what other protrusions are already on your roof.  This means you may need some additional MC4 connectors to build jumper wires to interconnect the panels.

Your diagram doesn't really cover how you plan to make the roof entry (get the 10 AWG wires through the roof).  I would use something like this.  This would replace #5 and #7 in the parts list on your diagram.  Those items are just strain relief like you see sticking out of the item I linked.  You will still need something to mount those strain relief in.  The item I linked is all you need to make the penetration (penetration cover and strain relief in one).

Finally (if you don't already have one) I would add a battery monitor as well.  Something like the Victron SmartShunt.  It will let you know the state of your batteries and will talk to the MPPT to help coordinate the charging and better maintain your batteries.  You can create a local Bluetooth network for the Victron components to talk to one another with the Victron Connect app.

[Zulu]

11 hours ago, Chad Heiser said:

I don't know if you just missed it in your diagram, but you want 4 AWG wire on both sides of the Baby Box for the battery side of the circuit. You also want 4 AWG lugs instead of the 6 AWG lugs in the parts list (#14) to go with the upgraded wire size.

I would also change to the proper rated circuit breaker for the MPPT 150/70 (at least a 70 amp, but more likely an 80 amp instead of the 60 amp in your parts list).  You are sizing the breaker for the wire (4 AWG) and the output of the solar controller.

Yep, missed those.

 

11 hours ago, Chad Heiser said:

I install 365 watt REC panels often.  (I have a large number of them on hand).  They are large panels (approximately 40" x 80").  I always install six panel mounts (z-brackets) per panel (three on each of the long sides).  The panels will flex too much with just four mounts on an RV.

 

Great tip, will do.

 

11 hours ago, Chad Heiser said:

Your diagram doesn't really cover how you plan to make the roof entry (get the 10 AWG wires through the roof).  I would use something like this.  This would replace #5 and #7 in the parts list on your diagram.  Those items are just strain relief like you see sticking out of the item I linked.  You will still need something to mount those strain relief in.  The item I linked is all you need to make the penetration (penetration cover and strain relief in one).

 

Thanks for link.

 

11 hours ago, Chad Heiser said:

Northern AZ's diagrams are fine. 

 

They wouldn't send me one until I buy a system. So I had to create my own.

 

11 hours ago, Chad Heiser said:

Finally (if you don't already have one) I would add a battery monitor as well.  Something like the Victron SmartShunt.

Yep, my 500A one is arriving today. However, have heard that its Bluetooth range is about 10'.

 

11 hours ago, Chad Heiser said:

The MNEPV breakers are directional in a DC circuit.  They come labeled with a + on one side of the breaker and a - on the other side of the breaker.  The + side of the breaker always connects to the highest potential of energy.  On the battery circuit, that would be the battery side.  On the PV circuit, that would be the panel side.

Was aware of this one from reading MidNite Solar ETL Test Article a few years back.

Again, much thanks, Chad.

[hemsteadc]

1 hour ago, Zulu said:

Yep, my 500A one is arriving today. However, have heard that its Bluetooth range is about 10'.

My Victron BMV-712 bluetooth is good for about 40'. The one little quirk is that it insists I have Location service turned on on my Android phone.  I guess Verizon's updates or checks turn it off.  Kinda annoying.

Edited January 12, 2022 by hemsteadc

[GlennWest]

My Smart shunt range is terrible. 

[Chad Heiser]

The Bluetooth range of Victron's equipment is very dependent on the installation.  Location and surrounding equipment/obstructions can greatly affect the range.  This is so with any Bluetooth device and it is something to be aware of when installing your equipment.  My experience so far has been pretty good, but some installations are better than others as far as affecting range.

[Zulu]

4th RV Solar Install here we come . . .

 

[Chad Heiser]

32 minutes ago, Zulu said:

4th RV Solar Install here we come . . .

 

Looks good.  A couple of minor things.

1.  I would put the class T fuse right after the battery terminal, before the house battery disconnect.

2.  The BMV 712 monitor does not work with a Smart Shunt.  It works with a standard Shunt and comes packaged together with the proper Shunt.  With a Cerbo GX and GX display, I would use the stand-alone SmartShunt rather than the BMV-712 with display and Shunt.  The BMV-712 display is totally redundant with a GX device and display.

3.  The VE Bus cable from the Cerbo to the MP2 is an RJ45, not an RJ12.

4.  I would consider adding a VE Bus Smart Dongle to the MP2.  This will give access the the MP2 via the VictronConnect App through Bluetooth.  It is necessary with the GX device, but I like the VictronConnect app interface to turn the inverter on and off and to set the AC Current Limit better through the App than with the GX device.

[Zulu]

1 hour ago, Chad Heiser said:

Looks good.  A couple of minor things.

1.  I would put the class T fuse right after the battery terminal, before the house battery disconnect.

I with you on the rest, but this one always puzzled me.

If you put the T-fuse right after the batteries and it blows, how could you safely replace it?

 

Tx again,

Tom

[GlennWest]

If you turn everything off that is connected to the fuse and discharge any capacitors, should be safe.

[Zulu]

6 hours ago, GlennWest said:

If you turn everything off that is connected to the fuse and discharge any capacitors, should be safe.

I don't think so. Here's my thinking . . .

[GlennWest]

my fuses are on the batteries.

[Randyretired]

I don't believe it matters.  In each case there is only a small amount of wire left connected to the circuit when the disconnect is opened.   Surely you could look to see if it is serviceable before connecting the fuse.

[Zulu]

3 minutes ago, Randyretired said:

I don't believe it matters.  In each case there is only a small amount of wire left connected to the circuit when the disconnect is opened.   Surely you could look to see if it is serviceable before connecting the fuse.

To replace the fuse you'll probably use a metal wrench to remove it from the holder. I'd rather not have one side of fuse holder hot.

[Randyretired]

6 minutes ago, Zulu said:

To replace the fuse you'll probably use a metal wrench to remove it from the holder. I'd rather not have one side of fuse holder hot.

If that is your preferred way I don't believe it matters.  However it is done one connection is hot.  Either at the batteries, switch or fuse and caution is the needed.  On edit one could just remove the ground terminal at the battery.  With the switch first the switch isn't fuse protected and that is why many prefer the fuse first.  Switch failures are not a problem from my experience.

Edited January 25, 2022 by Randyretired

[Chad Heiser]

No matter how you wire in the fuse (before or after the switch), you will be using a wrench on a hot connection during the installation.  You have to connect the wire to the battery positive terminal at some point and that is always hot.  It isn’t always under load though.  You can remove the load from the system by turning the switch off.  With the fuse before the switch, all components are protected, including the switch.

[Zulu]

On 1/25/2022 at 2:43 PM, Randyretired said:

If that is your preferred way I don't believe it matters.  However it is done one connection is hot.  Either at the batteries, switch or fuse and caution is the needed.  On edit one could just remove the ground terminal at the battery.  With the switch first the switch isn't fuse protected and that is why many prefer the fuse first.  Switch failures are not a problem from my experience.

I'll go with the flow in this one. I think every schematic I've seen, including from Victron, shows the Class T fuse before the disconnect switch.

Also, after talking with a guy who used to do marine inverter installs, I updated my schematic and added an AC disconnect right before the inverter along with other changes people suggested.

Thanks folks!

Edited January 27, 2022 by Zulu
SV agreement

[GlennWest]

Closer fuse is to battery the most protection. Everything uphill is protected. Downhill not