Question What does the inverter actually power, and when?

[TJ&LadyDi]

After yesterday's experience with an "inverter fault," I've been wondering just what the inverter power, and when. We're an all-electric coach and I know that the AC units do not run when we are not connected to park power. Neither doe the microwave/convection oven.

I also know that our AC refrigerator/freezer runs when we are not connected to park power, as does the induction stovetop and many, if not all, of the 120V wall outlets.

What I'm not sure of is when we are connected to park power, is the inverter bypassed or are those appliances always powered through the inverter and the batteries kept charged by the incoming AC power to the charger?

Thoughts?

TJ

 

[Neal]

As to what is powered by your inverter the best way to tell is go to your circuit breaker panel as one side is on shore power, the other side is inverter powered and Newmar may actually use different colors for the labels. I know in @ARD's DSDP her inverter breaker labels have a grey background.

As to whether the inverter is bypassed or not I don't know when on shore power. Paging Dr. @Chuggs

 

[Just George]

On our 2015 Ventana the inverter is in the loop and passing through power when we are on shore power and on generator. Had the inverter fault a while back while on shore power and trying to run the microwave and air fryer along with TV and various other low current items at the same time. Our microwave does run on the inverter however the coach is not all electric so that may be a reason for the difference.

 

[Chuggs]

Not really “bypass“...but “pass thru”. The inverter is supplying the electrical energy to the inverter sub panel. Only difference is...it is using the Main AC as the source vs the batteries. It could also be supplying electrical power to the batteries per your selected charge profile.

 

[RandyB]

When using the inverter, be aware of loads on the batteries. The loads mounts up very rapidly. As an example, this calculator is available at:
Calculate AC to DC Amperage Through Inverter | BatteryStuff

You can see that a relatively minimal 10 amp load on 120 volts alternating current (VAC) (house current), equates to 110 amps of battery volts direct current (VDC). Now, that big expensive and not-so-readily-available fuse at 250 to 350 amps can be overloaded very quickly. An accumulation of a couple more high wattage devices can easily pop that fuse.

My recommendation (and mine alone): anything that heats anything should not be run by the batteries and inverter. That would include a cooktop, a hair dryer, a curling iron, a coffee maker, a slow cooker, an oil cooker, a water heater, a space heater. If those items are required, it is a lot safer and less-problematic to simply start the generator.

When on shore power, the 120VAC is passed through the inverter to directly power those devices. The batteries are being charged by the converter side of the inverter, but they are not powering any devices.

 

[Chuggs]

The photo of the load center best describes it.

Please think of this photo when you are looking at your breaker panel. There are three rails across the top. Two staggered to the top left...and a single rail on the top right.

The top left are being electrified, if you will, by the two 50A breakers. They each get up to 50A “Leg” of power. They distribute this to all the circuit breakers that share their respective rail connection. Alternating between Leg 1 and Leg 2 from your service input.

If you look along that grouping...there is one 30A breaker labeled Inverter. That is the route that shore or generator power takes to get to the input side of the Inverter. The inverter has another power source (DC) coming from the battery bank...usually thru a 350A catastrophic fuse in the battery compartment.

Now...once the Inverter decides what it is using...it’s output comes back to this load center on the far right. A 30A Inverter Main. It distributes this power to all the other breakers sharing that smaller common “Inverter subpanel” rail.


I hope that makes it easy. Knowing what is going on in the background...you can easily see where things are powered just by looking at the breakers in your panel. It helps to know how the Inverter ties in...

 

[BigFunBus]

Hi TJ...
I'm kinda a visual guy so here's a pic from my 2015 Ventana.
At first glance the breaker panel all looks the same - but - with a closer look the left portion are the breakers for shore power/generator only (I added the "L1" & "L2" labels so I could keep the legs balanced as I moved circuits back/forth around the panel). The right side is powered by the inverter when no shore or generator is available. Also on my panel, the breaker numbers on the inverter side are highlighted in black (see the purple arrow).

I've learned that when you connect shore power or start your generator the inverter stops inverting (it stops turning 12 volts into 120 volts) and goes into "Standby Mode". When the inverter is in Standby Mode the 120 volt shore/gen power passes through the inverter to the inverter side of the breaker panel. I'm not sure how the inverter does this. The manual describes it in a couple of pages with color drawings with cool looking symbols; personally I believe it is magic.

Sooooo... on my panel, the things hooked to the breakers on the right side of the panel will run off the inverter. I moved some circuits from the shore/gen side to the inverter side when solar and big batteries were added but if you take a look at your breaker panel it should give you some indication of what the inverter will power.

Hope this helps.
joe

 

[Chuggs]

Hi TJ...
I'm kinda a visual guy so here's a pic from my 2015 Ventana.
At first glance the breaker panel all looks the same - but - with a closer look the left portion are the breakers for shore power/generator only (I added the "L1" & "L2" labels so I could keep the legs balanced as I moved circuits back/forth around the panel). The right side is powered by the inverter when no shore or generator is available. Also on my panel, the breaker numbers on the inverter side are highlighted in black (see the purple arrow).

I've learned that when you connect shore power or start your generator the inverter stops inverting (it stops turning 12 volts into 120 volts) and goes into "Standby Mode". When the inverter is in Standby Mode the 120 volt shore/gen power passes through the inverter to the inverter side of the breaker panel. I'm not sure how the inverter does this. The manual describes it in a couple of pages with color drawings with cool looking symbols; personally I believe it is magic.

Sooooo... on my panel, the things hooked to the breakers on the right side of the panel will run off the inverter. I moved some circuits from the shore/gen side to the inverter side when solar and big batteries were added but if you take a look at your breaker panel it should give you some indication of what the inverter will power.

Hope this helps.
joe

View attachment 2590

What size Inverter do you have??? 50A input to subpanel with cooktop and rear AC??? Wow !!! Somebody upgraded something.

 

[TJ&LadyDi]

Thanks, folks.

Here's a photo of my electrical cabinet. I think the MADP may be different than the DSDP and VTDP; we have two separate breaker panels side-by-side, as shown.

We were incorrect in saying that the microwave does not work off the inverter; it does. I just dropped the park power to confirm that. LadyDi was sure it didn't. We do have the all-electric option in our coach with 3K watt Xantrex inverter and 8 AGM batteries.

Since the breakers in the smaller black panel are labeled for the three slides, "reefer" and microwave, I think that is the inverter side. The larger gray panel at the right is labeled for things like the block heater, washer, dryer, Oasis electric heater elements, inverter, etc. This would be the AC breaker panel.

And, the "pass-through" explanation offered by @Chuggs on how the inverter powers things makes sense. Apparently, the inverter senses the presence of 120VAC and passes it through. When no AC is sensed, it substitutes power produced from the batteries. That's kind of what I was trying to say when I called it a "bypass."

Thanks, folks for helping me sort this all out and get a handle on it. One tiny grain of sand chipped off the granite block that rests on my shoulders.

TJ

 

[Neal]

Hi TJ...
I'm kinda a visual guy so here's a pic from my 2015 Ventana.
At first glance the breaker panel all looks the same - but - with a closer look the left portion are the breakers for shore power/generator only (I added the "L1" & "L2" labels so I could keep the legs balanced as I moved circuits back/forth around the panel). The right side is powered by the inverter when no shore or generator is available. Also on my panel, the breaker numbers on the inverter side are highlighted in black (see the purple arrow).

I've learned that when you connect shore power or start your generator the inverter stops inverting (it stops turning 12 volts into 120 volts) and goes into "Standby Mode". When the inverter is in Standby Mode the 120 volt shore/gen power passes through the inverter to the inverter side of the breaker panel. I'm not sure how the inverter does this. The manual describes it in a couple of pages with color drawings with cool looking symbols; personally I believe it is magic.

Sooooo... on my panel, the things hooked to the breakers on the right side of the panel will run off the inverter. I moved some circuits from the shore/gen side to the inverter side when solar and big batteries were added but if you take a look at your breaker panel it should give you some indication of what the inverter will power.

Hope this helps.
joe

View attachment 2590

Yours appear randomly wired sadly, you have "AC Rear" on the right of your line too which should be on shore power only.

 

[Neal]

Thanks, folks.

Here's a photo of my electrical cabinet. I think the MADP may be different than the DSDP and VTDP; we have two separate breaker panels side-by-side, as shown.

View attachment 2593

We were incorrect in saying that the microwave does not work off the inverter; it does. I just dropped the park power to confirm that. LadyDi was sure it didn't. We do have the all-electric option in our coach with 3K watt Xantrex inverter and 8 AGM batteries.

Since the breakers in the smaller black panel are labeled for the three slides, "reefer" and microwave, I think that is the inverter side. The larger gray panel at the right is labeled for things like the block heater, washer, dryer, Oasis electric heater elements, inverter, etc. This would be the AC breaker panel.

And, the "pass-through" explanation offered by @Chuggs on how the inverter powers things makes sense. Apparently, the inverter senses the presence of 120VAC and passes it through. When no AC is sensed, it substitutes power produced from the batteries. That's kind of what I was trying to say when I called it a "bypass."

Thanks, folks for helping me sort this all out and get a handle on it. One tiny grain of sand chipped off the granite block that rests on my shoulders.

TJ

Yes, yours is very different being separate. On first thought I figured that's nice, then I realized you have no way to add things to the inverter circuit such as several of us have put the option to drive the front AC off of inverter (solar backed). I guess you would have to replace the panel but moot as I know that's not something you would do, just my analysis of the difference in what I have vs. the MADP.

 

[TJ&LadyDi]

Yes, yours is very different being separate. On first thought I figured that's nice, then I realized you have no way to add things to the inverter circuit such as several of us have put the option to drive the front AC off of inverter (solar backed). I guess you would have to replace the panel but moot as I know that's not something you would do, just my analysis of the difference in what I have vs. the MADP.

Actually, it looks like there is room for one more double breaker if you cut out the front panel. That assumes that the buss bar goes all the way across. Otherwise, changing out the box for one that would take the fifth set of double breakers would not be a big deal; 20 minutes work at most.

TJ

 

[J&JD]

What am I missing here? If TJ was hooked to shore power, and the inverter is passing through that 120v power source, why would the breaker on the inverter pop? Shouldn’t all the load be absorbed by shore power leaving the inverter in a “passive pass through mode”. Probably a simple answer Out there for a befuddled guy??.

 

[TJ&LadyDi]

I have the same question! And, I didn't get an answer from the Newmar tech when I asked. Anyone?

Dr. Chuggs, please report to the forum!

TJ

 

[Just George]

Well I'm not Dr. Chuggs but here's my explanation based on my understanding of typical inverter operation. When an inverter is in "standby" or pass through mode it is passing the input AC voltage through to the inverter AC output. The wiring and components (transfer relay etc.) within the inverter cannot handle an unlimited amount of current so there is at least one circuit breaker in line to protect the inverter. Most if not all will have a circuit breaker on the AC input, some may also have circuit breakers on the AC output. In addition to the circuit breaker protection some inverters have built in overload protection that will shut down the inverter in the event of an overload condition. The inverter can then be restarted once the overload condition is addressed.

 

[TJ&LadyDi]

Well I'm not Dr. Chuggs but here's my explanation based on my understanding of typical inverter operation. When an inverter is in "standby" or pass through mode it is passing the input AC voltage through to the inverter AC output. The wiring and components (transfer relay etc.) within the inverter cannot handle an unlimited amount of current so there is at least one circuit breaker in line to protect the inverter. Most if not all will have a circuit breaker on the AC input, some may also have circuit breakers on the AC output. In addition to the circuit breaker protection some inverters have built in overload protection that will shut down the inverter in the event of an overload condition. The inverter can then be restarted once the overload condition is addressed.

Thanks for that explanation. I suspect that we had an "overload" and tripped the inverter breaker, thus disabling all operation, including pass through. Too many fashion-conscious ladies aboard. "Did I say that?"

TJ

 

[J&JD]

Thanks for that explanation. I suspect that we had an "overload" and tripped the inverter breaker, thus disabling all operation, including pass through. Too many fashion-conscious ladies aboard. "Did I say that?"

TJ

Well I'm not Dr. Chuggs but here's my explanation based on my understanding of typical inverter operation. When an inverter is in "standby" or pass through mode it is passing the input AC voltage through to the inverter AC output. The wiring and components (transfer relay etc.) within the inverter cannot handle an unlimited amount of current so there is at least one circuit breaker in line to protect the inverter. Most if not all will have a circuit breaker on the AC input, some may also have circuit breakers on the AC output. In addition to the circuit breaker protection some inverters have built in overload protection that will shut down the inverter in the event of an overload condition. The inverter can then be restarted once the overload condition is addressed.

Well I'm not Dr. Chuggs but here's my explanation based on my understanding of typical inverter operation. When an inverter is in "standby" or pass through mode it is passing the input AC voltage through to the inverter AC output. The wiring and components (transfer relay etc.) within the inverter cannot handle an unlimited amount of current so there is at least one circuit breaker in line to protect the inverter. Most if not all will have a circuit breaker on the AC input, some may also have circuit breakers on the AC output. In addition to the circuit breaker protection some inverters have built in overload protection that will shut down the inverter in the event of an overload condition. The inverter can then be restarted once the overload condition is addressed.

So you’re saying it was TJ’s curling iron that was to blame?

 

[TJ&LadyDi]

So you’re saying it was TJ’s curling iron that was to blame?

TJ would be happy to find something on his ol' noggin to curl! Now, TJ's daughter and granddaughter are a different story. Rest assured, we will be having a family conference on RV etiquette in the near future.

TJ

 

[Joe Hogan]

Luckily Newmar does a decent job of labeling electrical circuits. Newmar does NOT maintain a wiring diagram for your coach. I have tried and tried to get a diagram to no avail.
However, when at Newmar Service center, ask one of their electrical techs, they can tell you immediately where a factory install wire or circuit is located.
This year at Newmar Service Center I discussed a short in the basement lights (caused by Solar installer it turns out) that we had been chasing for 8 months ( two techs at various times during the year were unable to find the fault,).
The Newmar tech looked at the RV, hooked up fault finder, and knew right where to look. Found and fixed the issues within 45 minutes. That included removing and reinstalling the fireplace.

 

[RandyB]

Clip from Magnum MS Series manual: