Whole RV Inverter/Charger

[LipschitzWrath]

Not a lot of information out there so I figured I'd post here.

If like to add an inverter for my 5er, mainly to limit inconvenient trips out to get the generators running for small things. One of the first things that comes to mind is the coffee pot. That's about the only AC power we use in the morning.

Anyways, I have this ambitious goal to have the inverter be capable of powering the whole camper, rather than just a few outlets or a sub panel or whatever. I'd also like to do a combo inverter/charger (IC) in place of my converter to streamline things, especially the transfer switch duties. I'm trying to confirm my thinking is correct.

The inverter I'd like to use is a Victron Multiplus 12/2000/80.

In my mind, the way this would be accomplished is to take the wire that is normally connected to the shore power inlet on the side of the camper and connect it to the AC output side of the IC. I would then run wire from the actual shore power input receptacle to the input side of the IC. With the transfer switch capabilities of the Victron, it seems like this would work correctly when plugged into shore power or portable generators, yet still let the whole RV function off the inverter when not. Am I correct?

Next question. Technically my RV is set up for a 50A, 240V input. I normally run it off of 120V. I'm assuming my RV is set up like a house - half the 120 circuit in the box come off of L1 on the 240V and the other half come off L2. If I'm correct, wouldn't I technically need two IC's as illustrated in Victron's "split phase" diagram?

Any help is much appreciated.

[LipschitzWrath]

MrWizard wrote:
power from a utility source, coming into a breaker

is NOT a back feed, you re mis-construing term, just because of the location of the breaker

anyway it does not apply to what you want to do

Whatever. I'm over it. I quote NEC code and you quote your memory. Try to get a building permit based on what you *think* is correct versus what the NEC says.

[MrWizard]

power from a utility source, coming into a breaker

is NOT a back feed, you re mis-construing the term, just because of the location of the breaker

anyway it does not apply to what you want to do

I won't mention it anymore

what is important is the correct separation of the circuits involved
and you have your designed laid out

[LipschitzWrath]

MrWizard wrote:
there is confusion
you mentioned 50amp. i thought you had a 50amprv
you mentioned (2) a/C

are you rewiring a 30 amp rv for 50amp

and yes. no generator, no TS

the input lugs, would be for input IF there was a meter and main before the panel
all RV's have a main breaker, "that is not a back feed"

I gave you the definition of back feed

feeding from someplace that is illegal

example : if you removed the current main breaker and installed another breaker box with the shore feed and the inverter feed and (2) breakers with a manual lockout selector so only one could be used
you could connect that to those input lugs at the bottom of the panel are currently 'unused' that would be safe and legal

your current use of the term 'back feed' can cause confusion, and mis-direction
code says there has to be an input breaker
that breaker can be in the panel (the one you have now) or outside the panel in another box (often done in commercial wiring, not done in RV's)
a main breaker in the panel like you have it is LEGAL CODE, not back feeding

but that is beside point (just clarification)

Rv *IS* 50 amp. I'm not talking about rewiring anything to 30A, someone else suggested that to reduce need for 2 inverters to 1. We have progressed past that.

I never said the RV had 2 ac units, only two circuits in the breaker panel. Like I said, it's entirely possible that circuits doesn't power anything.

I think you are confused or have been led to believe that back feeding is somehow illegal. It's not. Not at all. It's a completely acceptable practice. Again, I encourage you to look at the NEC 408.36d. No matter what, NEC is right and you and I are wrong. There is still circuit protection with back feeding - a breaker doesn't care what direction the current is traveling.

We have already drug this out too far and are probably losing people from this thread but you are the one that is wrong and adding to the confusion. Before you reply in anger, please do some research and educate yourself as I'm sure you will find that you are the one that is misinformed about the definition of back feeding.

Now, let's please get back to the issue at hand.

[MrWizard]

there is confusion
you mentioned 50amp. i thought you had a 50amprv
you mentioned (2) a/C

are you rewiring a 30 amp rv for 50amp

i see a double pole 50 amp main in your pictures
(coming from your shore power plug?)

so yes my comments about power distribution are very on topic
yes (1) a/c does simplify the power distribution
i would still split the loads on what will be used with shore/generator (with 30amp they will all be on the same leg anyway)
panel distribution will only come into play when, when on 50 amp shore power, and then you 'want the real use balanced'

do you have a roof top a/c or basement a/c ?
basement a/c might have (2) compressors
only (1) a/c breaker has wire ? the other is empty ?

(you never ever go to a campground with 50 amp hookup ?)

and yes. no generator, no TS

the input lugs, would be for input IF there was a meter and main before the panel
all RV's have a main breaker, "that is not a back feed"

I gave you the definition of back feed

feeding from someplace that is illegal

example : if you removed the current main breaker and installed another breaker box with the shore feed and the inverter feed and (2) breakers with a manual lockout selector so only one could be used
you could connect that to those input lugs at the bottom of the panel are currently 'unused' that would be safe and legal

your current use of the term 'back feed' can cause confusion, and mis-direction
code says there has to be an input breaker
that breaker can be in the panel (the one you have now) or outside the panel in another box (often done in commercial wiring, not done in RV's)
a main breaker in the panel like you have it is LEGAL CODE, not back feeding

but that is beside point (just clarification)

[LipschitzWrath]

MrWizard wrote:
this keeps the neutral leg from being overloaded by an imbalance

This is absolutely wrong. The two 120V legs are not in phase with each other so there is no way the neutral leg can be overloaded. If that were true, 240V services would use 6ga wiring for L1 and L2 and 2ga (or bigger) for N. They don't because the maximum current that can ever travel down the N wire is whatever is coming in from L1 *OR* L2, or the sum. However, the sum can never exceed what L1 or L2 can carry separately, because they are 180 out.

This is precisely how you get 240V power at home.

[LipschitzWrath]

Mr wizard wrote:


NO thats not back feeding
those are out put breakers going to the sub panel

NO. Those are the feeds INTO the panel. That's why the screw is there. Check your NEC 408.36d. The screw wouldn't be there if those were output circuits

Mr wizard wrote:
back feeding is when you bring hot "power in" from what is leagally and output circuit

Yep, just like the breaker panel on my RV.

Mr wizard wrote:
take a double ended suicide cord
plug end 'B' into an outlet in the RV
plug end 'A' into a shore outlet

THAT IS BACK FEEDING

I guess that's back feeding, but it's a pretty contrived way to do it and that's not really analogous to what we're talking about here.

Im not saying that backfeeding is a bad thing, just trying to describe it to give a visual before I could post pictures. It has obviously caused more harm than good with you.

Mr wizard wrote:
so the guy at fleetwood, messed up
and you re-balanced it..good
i never said not to re-balance
i said don't put all the heavy items on one leg
i would separate the (2) A/C they are the two big items most likely to be on for hours at a time thw other loads are more intermittent, this keeps the neutral leg from being overloaded by an imbalance
rearrange the other loads
having an a/c on the inverter leg won't hurt
you won't be running the a/c with out the genny or shore, not near as likely to forget as say the WH or fridge
tv, outlets, ceiling fan, MW, IMO must have for inverter
A/C can be on that circuit and the washer/fireplace IF you want, the victron pass thru will handle it when using genny or shore power and those are items not likely to be accidentally left on, or come on automatically (victron is an excellent choice)

and unless you have a Manual lock out breaker switch arrangement for generator and shore choice, there is a 50 amp 3pole TS someplace, mine is a big silver box in the electric bay, because my breakers are in the cabinet over the BED

I see now that we have some confusion. First of all, I don't have 2 ac units, only one. Hell, for all I know, the AC2 circuit is a spare. I figured they split it across two breakers to use smaller breakers. And yes, I only use it with the generators.

Also, I do NOT have an on board generator. I use two Yamaha suitcases. So, currently, the only way to get AC power into the trailer is through the shore power receptacle on the side. So to say that I MUST have a transfer switch somewhere is erroneous, I believe.

Mr wizard wrote:
yes in some respect
but 30amp RV don't come with electric heat fireplace and washer dryers
and the (2) a/c only run on generator, RV is usually setup that only (1) a/c can be run on shore power, then its power management time for MW etc..
its not all run at the same time when the RV has 30amp main

But I doubt the engineers designing all this were playing a game of Russian roulette, betting on what you will and won't run at the same time. I can't run the fireplace and WD at the same time, they are wired to a toggle switch so it's one or the other. And again, only 1 AC unit.

I guess what I was trying to say is I think load balancing is less of a concern than you are making it out to be because there is nothing a 30A 120v service can do that a 50A 240v service can't do, even on one leg.

Can I run my entire camper at the same time from 1 leg if I put it all on one leg? Don't know. But I can guarantee you that if I can't with my setup, there's no way you can with your 30A 120V setup. There is, however, the possibility that I can and the 30A setup can't. That's all I'm saying.

[MrWizard]

Yes, I know houses have main breakers - except that they're not usually down in the the same breakers as all the branch circuits. They're usually up above the branch breakers and separated. However, if you feed a small subpanel in a garage that doesn't have main breakers and you use 2 breaker slots where branch circuits would go to feed the panel, that's backfeeding. I can tell you which one mine looks like

NO thats not back feeding
those are out put breakers going to the sub panel

back feeding is when you bring hot "power in" from what is leagally and output circuit

take a double ended suicide cord
plug end 'B' into an outlet in the RV
plug end 'A' into a shore outlet

THAT IS BACK FEEDING

I hear what you are saying, and I don't disagree. However, it would seem your advice would be better vetted with Fleetwood, as they certainly didn't follow your advice. This is how my panel came wired from the factory (refer to photo above if you doubt it).

L1: GFI (15A) [most outlets in camper], A/C 1 (20A), A/C 2 (20A), Microwave (20A), Water heater (15A) ----- TOTAL: 90A

L2: Fireplace / Washer-Dryer (15A), Refrigerator (20A), Ceiling Fan (15A) [other outlets, TV, stereo], Converter (15A) ----- TOTAL: 65A

Would you call that balanced? Cuz I wouldn't. Moving AC1 and AC2 onto L2 and bringing the ceiling fan circuit over to L2 doesn't look like that big of a change to me. It looks better, in fact. The converter circuit would become a spare as the inverter would take over those duties. New "total" amperages would be:

so the guy at fleetwood, messed up
and you re-balanced it..good
i never said not to re-balance
i said don't put all the heavy items on one leg
i would separate the (2) A/C they are the two big items most likely to be on for hours at a time thw other loads are more intermittent, this keeps the neutral leg from being overloaded by an imbalance
rearrange the other loads
having an a/c on the inverter leg won't hurt
you won't be running the a/c with out the genny or shore, not near as likely to forget as say the WH or fridge

tv, outlets, ceiling fan, MW, IMO must have for inverter

A/C can be on that circuit and the washer/fireplace IF you want, the victron pass thru will handle it when using genny or shore power and those are items not likely to be accidentally left on, or come on automatically
and you might use the washer at the same time as the A/Cs are running
but unlikely to use fireplace and A/C
BTW (victron is an excellent choice)

and unless you have a Manual lock out breaker switch arrangement for generator and shore choice, there is a 50 amp 3pole TS someplace, mine is a big silver box in the electric bay, because my breakers are in the cabinet over the BED

Better than it was before. Besides, you guys running 120V only feed all the same stuff I have on both legs from 1 leg, and are limited to less current (usually 30 amps). I have two legs and each one can carry 66% more current than that. I understand what you are saying from a theoretical standpoint, but it isn't relevant in practice.

yes in some respect
but 30amp RV don't come with electric heat fireplace and washer dryers
and the (2) a/c only run on generator, RV is usually setup that only (1) a/c can be run on shore power, then its power management time for MW etc..
its not all run at the same time when the RV has 30amp main

its mainly the 50amp rv guys that come on here trying to run both A/Cs from a 30amp campsite and asking how to do it because they keep tripping the 30amp breaker at the pedestal

with 30amp rv there is usaully a switch to choose which a/c front or rear, or one is hard wired to the genny with NO switch no choice

[LipschitzWrath]

MrWizard wrote:
thinking 'not correct'

its normal to have a main breaker in a house.
this is 'not backfeeding'

Yes, I know houses have main breakers - except that they're not usually down in the the same breakers as all the branch circuits. They're usually up above the branch breakers and separated. However, if you feed a small subpanel in a garage that doesn't have main breakers and you use 2 breaker slots where branch circuits would go to feed the panel, that's backfeeding. I can tell you which one mine looks like.

Backfed subpanel:


My breaker panel:


My "main" breakers even have the screw required when you backfeed a panel. I don't believe my description was inaccurate.

MrWizard wrote:
moving loads around for 'balance is good'
moving loads so all high draw items are on ONE LEG is 'BAD'

especially since you want the (2) a/c on separate legs
wh on one leg, MW on the other leg

I hear what you are saying, and I don't disagree. However, it would seem your advice would be better vetted with Fleetwood, as they certainly didn't follow your advice. This is how my panel came wired from the factory (refer to photo above if you doubt it).

L1: GFI (15A) [most outlets in camper], A/C 1 (20A), A/C 2 (20A), Microwave (20A), Water heater (15A) ----- TOTAL: 90A

L2: Fireplace / Washer-Dryer (15A), Refrigerator (20A), Ceiling Fan (15A) [other outlets, TV, stereo], Converter (15A) ----- TOTAL: 65A

Would you call that balanced? Cuz I wouldn't. Moving AC1 and AC2 onto L2 and bringing the ceiling fan circuit over to L1 doesn't look like that big of a change to me. It looks better, in fact. The converter circuit would become a spare as the inverter would take over those duties. New "total" amperages would be:

L1 - 65A
L2 - 75A

Better than it was before. Besides, you guys running 120V only feed all the same stuff I have on both legs from 1 leg, and are limited to less current (usually 30 amps). I have two legs and each one can carry 66% more current than that. I understand what you are saying from a theoretical standpoint, but it isn't relevant in practice.

MrWizard wrote:
NO NO do not feed the bottom panel lugs from the inverter
there is way too much chance of blowing up the inverter from shore power or generator

Dude, thank you for helping me pull my head out. I dunno WTF I was thinking. The Victron has a built in transfer switch. I could intercept the shore power wiring from the outside receptacle and wire that into the Victron on the L1 side and leave the L2 side feeding straight through, untouched. This would automatically feed the L1 leg from the inverter when not hooked to shore/gen and keep it completely isolated from L2. Duh!

I guess I saw open lugs and figured I was making out good. Who knows.

MrWizard wrote:
get a 50 amp rv transfer switch
install it after the existing TS, us it to choose between (existing) or inverter

if you want to isolate circuits automatically, instead of remembering that certain things need LP only

then install a sub panel for the inverter circuits and move them there

RV does not have an existing transfer switch of any kind (unless it came with one as part of the gen prep package and I can't find the **** thing).

[CA_Traveler]

Agree with Wiz.

[MrWizard]

thinking 'not correct'

its normal to have a main breaker in a house.
this is 'not backfeeding'

moving loads around for 'balance is good'
moving loads so all high draw items are on ONE LEG is 'BAD'

especially since you want the (2) a/c on separate legs
wh on one leg, MW on the other leg

NO NO do not feed the bottom panel lugs from the inverter
there is way too much chance of blowing up the inverter from shore power or generator

get a 50 amp rv transfer switch
install it after the existing TS, us it to choose between (existing) or inverter

if you want to isolate circuits automatically, instead of remembering that certain things need LP only

then install a sub panel for the inverter circuits and move them there

[LipschitzWrath]

Okay guys, I pulled my breaker panel apart and found some promising things.

As suspected, half the circuits are fed from L1 and half from L2. They are staggered, so every other {full} breaker position on each half of the panel is fed from L1 and L2.

I checked all the outlets and found every outlet in the camper is fed from one of two breakers, and neither of those breakers serve any high draw items, like AC, refrigerator, etc. The TV and stereo system are also fed from one of those breakers. The microwave is on its own breaker.

My breaker panel accepts "half-breakers" in all positions, so I could add up to 3 more breakers (all breaker positions are currently occupied, but 3 of the positions use "full" breakers and could be substituted for "half" breakers).

Lastly, the panel has two big lugs at the bottom that could be used to feed either L1 or L2 from the inverter. They look like they were intended to be the actual L1 and L2 feeds into the panel, but I have separate 50A breakers in two positions that serve as the feeds. I guess to borrow terminology from house wiring, the panel is "backfed" through two 50A breakers.

My thinking was that I could move all the circuits I want to power from the inverter onto either L1 or L2 (whichever makes the wiring easier). Worst case, this would involve moving breakers and branch wiring from one position to another in the fuse box. It looks like there is ample slack in all the branch wiring to do so, as long as I don't try and move breakers from one side to the other.

I would then leave all the high-draw items on the opposite leg. My thinking tells me that this would accomplish the goal of powering what I want to power from the inverter without also powering high-amp stuff or having to worry about accidentally leaving the fridge on "Auto" and running the batts down when running on the inverter.

First of all, is my thinking correct?

I did think of one potential problem that I'd love to hear your guys' solutions to. For the sake of argument, let's say that I want my "inverter leg" to be L1. When I have my 30A shore power cord connected to the camper, L1 and L2 would be connected together. This would power both L1 and L2 from the inverter because inverter power would "enter" the CB panel from the L1 lug on the bottom, "leave" the CB panel through the L1 main 50A breaker, jump over to L2 in the shore power cord, then "re-enter" the CB panel through the L2 main 50A breaker, thus feeding all the L2 circuits as well.

Having L1 and L2 connected when on shore power or generators is preferable, having them connected when on inverter power is not. Is there an easy way to fix this? I was thinking some sort of "transfer switch" or relay that cuts off L2 when shore/gen power is not present on the L2 leg. When you fire up the gen or plug into shore power, the switch/relay would close, thus allowing AC power on the L2 leg. When off, power to the L2 leg would be cut off and inverter power would not have a path to the L2 leg.

Am I thinking about this correctly? Overthinking?

[MrWizard]

the micro-air won't make any difference in what can be run while the a/c is on

NOTHING with out the assisting inverter

the MA only assists the a/c in starting
it doesnot assist anything else

IF you install the multi plus , just unplug the fridge from the 120v outlet behind it
it will default to LP and stay there all the time
this is most efficient way to run an RV fridge any way
it really uses very LITTLE LP to operate
using the generator to make electricity for the RV fridge heating element is wasting 'fuel'
cool the fridge with LP
you won't have any switch over forgetfullness

[drsteve]

LipschitzWrath wrote:
Not a lot of information out there so I figured I'd post here.

If like to add an inverter for my 5er, mainly to limit inconvenient trips out to get the generators running for small things. One of the first things that comes to mind is the coffee pot. That's about the only AC power we use in the morning.

This one needs no AC power...

[LipschitzWrath]

CA Traveler wrote:
Power off, remove the CB panel and find out what circuits are on L1 and L2. Remove lights, speakers, etc and look for access. My cabinets have decorative inside panels that are held with wire brads and glue, easy to remove. You may need to remove under rig paneling for access. Interior walls are likely hollow. I’ve run wiring in exterior walls that have insulation. Check, be creative, etc.
Yes ATS = Automatic Transfer Switch, Victron let alone 2 is high dollar. How would you use one inverter for a whole house? You’ll need to switch those wires somehow.
Some charger/inverters have a built in ATS and CB protected outputs. No sub panel needed.
Many rigs have a built in gen and an ATS is used to automatically switch between shore power or gen power. So when you read about an ATS be clear about the application.
An charger/inverter can either charge the batteries from the charger or supply 120V from the inverter. It will automatically switch when it senses AC input but it does not do both at the same time. Some like separate units for various reasons but you have to manually select one or the other. Using the inverter output running from batteries to run the charger is a sure way to run down the batteries. No free energy.

I will check into the access. I guess I haven't looked as close as you are describing. However, the walls are not hollow (at least the exterior ones aren't), they are insulated. It's a 4-season camper (tank heaters, etc).

Yes, Victron are high dollar but if a requirement of the inverter is that it has an "assist" function, doesn't the list get pretty short? I think Magnum makes one (hybrid) but I thought I looked and it was twice the cost? What other manufacturers are out there that have a "boost" function?

My rig was gen prepped but no generator. I don't think it has an ATS anywhere. Another reason I was interested in the Victron is it has the ATS built in. I dunno what a seperate ATS costs, is it better to try and split them out?

If the inverter has CB protected outputs, does that mean if you tripped the breaker on that output, you'd have to run out to the inverter to reset? Not a deal breaker, just curious. I would be mounting this in the large under-storage compartment where the converter currently is mounted.

You're right, without connecting L1 and L2, there is no way to power the entire camper with 1 inverter. Your comment is what got me thinking - maybe I can use that to my advantage. That way I could make sure things like the fridge and water heater are on the other leg, so by default they are not powered by the inverter. It seems like I could just swap breakers and wires at the CB panel to make sure the aforementioned items are not on the same leg as the inverter.

Your other example of feeding the inverter from the the CB panel and then in turn feeding select circuits from the inverter would accomplish the same thing. I would just need to be able to get wire from the CB panel down to the inverter and back to power the right circuits.

Based on the usage I described in my last post, what kind of battery Ah do you think I'd need? I currently have 2x AGM group 31 batteries, 105 Ah each.