Inverter Transfer Function

Been doing some reading in my Heart Freedom 25 Inverter manual.

It states that there are two AC inputs. One for the "Charger" and the other for the "Transfer Switch".

My understanding is that when AC is available on the Transfer Input, a relay closes and passes the AC through without using inverter function.

It is also my understanding that on my 97 Liberty when batteries are below 10.5V and "Charger" breakers are OFF I have little or no AC available from Inverters.

Shouldn't the AC be available whenever coach is plugged in?

Or, does Liberty not use the Transfer Switch AC Input on the Heart Inverters?

Anybody know the lowdown on this??

Lee Bornstein
97 Liberty 40

Hi Lee, how ya been?

I am not an expert on Liberty operations or Heart inverters, but if the Leiberty dudes don't pipe right up, I am sure the techs @ Liberty would be happy to give you the lowdown.

If your voltage is in the 10's, your inverters should not be producing AC, (actually before that). But if you are plugged in, as stated the relays should be closed, and passing AC through to the coach, even if you are electing not to charge. I am not clear why you wouldn't want to charge too if you are plugged in?

My inverters allow you to set a "power sharing" value, so it adjusts the amount of AC it will draw for charging, to the amp rating of your service.

In theory, you should always have AC if you are plugged in, barring blown breakers!

How are things over @ ORA Vega$ ? I keep meaning to stop by and check that place out!

The Heart Inverters have two AC Inputs - One for the Charger and one for the Transfer Switch. The way I under stand it is if NO AC on Transfer Input then AC Output comes from Inverter. If AC IS on Transfer Input then Relay closes and passes AC through without using inverter function.

I'm guessing that Liberty - for some reason - does not use the Transfer Input and always relies on Inverter to produce AC. Only reason I can see for this is it allows you to draw more than 50A periodically. Washer/Dryer, Chargers, Air Cond, Water Heater and cook top are NOT on inverter so these devices could all be on drawing 50A from post and still allow Fridge, TV, Microwave, and outlets to run without overload.

Liberty does this with Water Also. All water I use comes from Tank. Autofill will refill water tank when it gets empty. Coach does no have ability to use city water directly without first going into tank and then being pumped to coach. Just like Batery Charger/Inverter.

I may be wrong but that's my theory on how I think my coach works.

Lee -\
Still on the road somewhere outside of Fargo ND...
Left Vegas to go to Pog III and havent gotten back yet.

Actually, on our Liberty if the water fill switch is off, and the water pump is off, city water pressure from the water supply will supply our coaches with water without depleting the tank.

The reason Liberty prefers to rely on the water pump is to provide the pressure and volume of water to flush the Headhunter toilet and provide water for other devices such as a faucet with no loss of performance.

As to the inverter set up the battery charger portion of the inverter is provided its own separate circuit, and unless that circuit is turned off, the batteries will be charged (as necessary) any time there is shore or generator power. The supply to the inverter is only a pass through as long as there is shore or generator power. When there is no shore or generator power the inverters are the source of power via the batteries. I do not know specifically why it is set up this way. Lee's thinking on this may be correct but I'm not clear on how the switches have to be set for this to happen.

I guess my main question is ... Why, when plugged into campground, does my AC Power in coach go off when I turn off the Inverter switch on the Heart Control Panel?

According to Documentation ....

"The internal transfer switch will continue to be engaged with the switch off and AC power will be available at the output of the unit. If AC power is removed the unit will not come on as an inverter."

Still puzzled...

Also, with regard to water... when connected to park water and pump is off I get water flow inside but at very low pressure. Not enough for a shower. I will stick with the pump.


Lee

Lee, sticking with the pump is exactly what Liberty prefers. In the campground water system it has to have both the water flow and the necessary pressure to flush the toilet while running a shower for example.

But, you can use campground supply only, but your pressure accumulator tank needs to be properly pressurized so it will deliver that initial flow otherwise you are solely dependent on the CG system. If your pump is short cycling the accumulator tank needs a shot of air pressure.

As far as the inverters requiring power this is only a guess. If it is an incorrect assumption someone needs to jump in here. If you turn off power to the inverter the relay that closes in the presence of shore or generator power does not close so that power source does not flow to the circuits supplied by the inverter.

I suspect if you turn off the inverters you do power things like the AC units or other circuits not powered by the inverter.

I've got a call in to Xantrex on the inverters. I'll let you know what they say when I reach them.

Lee

Spoke to tech at Xantrex today. He said that On/Off switch on Inverter remote turns off Inverter function as well as blocking AC Pass Through so with switch off, no AC on Output.

Tomorrow I'm going to unplug coach, turn off Charger, turn off house battery switch and then plug in coach and see if I get AC passed through inverter.

Lee

Lee
I had one Freedom 30 that didn't work as you explain and it was the transfer switch in the inverter. I have three and one wasn't working so I took it apart and found a wire that had come loose. I soldered it back to the post and everything was OK. If you can not isolated the problem to one inverter, assuming you have more than one, you make have a problem with the main transfer switch for CG, generator or inverter power. My coach has a delay while it switching from one source to the other where I have no lights.

Greg

On the water pressure problem fromCG source you may have too many pressure reducers inline. In my coach there is a built in reducer just after the water enters the coach and then I have a water filter that also reduces pressure. So if I put one on the hose at the CG spigot I think the flow gets even slower. When you use the Tank and pump you only have the filter in the system.

Just some thoughts

GregM

Greg, Our coaches use the headhunter toilet. The toilet uses little water per flush, but it wants the water it uses delivered rapidly under a decent pressure.

Regardless of inlet restrictions the key to successful operation in our coaches is downstream from any flow restrictors because from the pressure accumulator tank we have a 1" unrestricted line directly to the toilet. If the accumulator is water logged any pressure drop will bring our pump on line. The pump also provides high flow at high pressure.

If the pump is turned off and there is a reliance on CG water then it is imperative the accumulator tank is functioning properly.

More perplexing data on my inverters... Still makes me think Transfer switch doing nothing.

Static Condition...
AC - Campground Post is ON
Both Freedom25 Charger Breakers are OFF
No AC Load.
Inverter Switch is ON
Inverter Monitor Panel shows
DC Load Current of 0

Now - I Turn on some 120v Lamps, TV etc and I show 30A DC Load.

If Inverter is passing through AC from the CG Post then why do I see a 30A DC Load?

John - Can you try the above on your Liberty and see if you get similar results?


Lee

Lee, Assuming I read the conditions properly, if you have no AC input, the inverters are "on" and you turn on a 120V lamp you created a DC load.

The inverters are taking DC power from the battery (hence the load) and converting it to AC to light the lamps.

All our buses are slightly different, but another thing to consider is we have "phantom" loads. I have no clue what they all might be in my coach, but I know they exist. With every switch and device turned off (not the big master switches, but switches that control specific items) I still have a current draw such as the alarm systems, computers, radios, clocks, intercom, cell phone, etc.

I don't know how our displays are set up. I assume the DC load meter shows only that which is passing through the inverter and that the "phantom" loads only show up when the battery charger is functioning by displaying AC amps when all AC devices are turned off.

What we need is for the major converters to put on overview seminars so we can understand the general concept of how our coaches are set up. I imagine each converter is slightly different.

We've had FOUR Prevost coaches over the years (never more than one at a time) and have never received an adequate explanation from any converter or tech as to how in the world you can turn everything off in the coach and still have a load.

My feeble brain tells me that any load from an inverter or battery should have a) a fuse inline and b) some means of switching it off.

If that is the case, then a guy should be able to power down a coach completely, alleviating any draw whatsoever.

In our first coach, I pulled the front panel by the stairwell with all power shut down (so I thought) and found that the DC electrical bus was still hot. That's enough amperage to run a small welder, if you haven't checked.

The best answer I got from all of that was from one tech who said, "Hmmm."

It'd be a good idea to track this one down, especially of a coach is in storage without any AC input with the generator off?

Inquiring minds want to know.

Some of the "phantom loads" have a purpose. For example some radios require constant power just to retain memory. The alarm system is in standby mode. If the power to the clocks is turned off whenever the bus is stored then resetting the clocks is just one more thing required before a trip.

So the converters provide us with master disconnects in case we really do want to power down.

In my first bus I could turn off the batteries with a pair of big switch knobs (or by burning up the engine compartment and every battery in the bus), but by putting AC power to a pair of converters (not inverters) I had all the DC power I needed.

Each of our buses is different and there are times when it becomes extremely valuable to really know and understand how the systems work. At this point I can only surmise how my coach systems are set up.

Being new to the electrical nightmare of owning a Liberty I have to ask a dumb question. Is there an electrical schematic that the converter electrical techs follow when wiring the coach. Somehow I think the converters owe us a complete explanation of the above questions you have previously expressed. A series of color coded schematics showing the on and off circuits during each position of switches would be helpfull. Gary D get on this will ya.

Then you have to add to the formula, what the previous owner (s) did. We were the thrid owner of ours and I think that the first owner had it a couple of year and then the second owner had it 10 years. So in the time the second owner had it, I think a few of the stock items had been change out. I know I don't have the original inverter and dash air compressor. Each time someone touches these bus's including me, it does not follow the original diagrams. This is why the network of bus owners is so nice to have, plus the friends you make.

It is really important that a bus owner try hard to understand each of the systems on their bus.

Lee
What happens when you run the generator? Are you getting pass thru current without a DC load?

With the coach plugged into CG power and some lights on turn off the CG breaker. Do you hear a clunking noise like the transfer switch is functioning?

GregM

Yes, I hear clunk when turning CG Breaker ON.

As I understand it there are Three (3) Transfer switches.
One that switches AC Sources between Generator and CG Post to Inverters and anything else using AC Power. Also, Each Inverter has a transfer switch that's supposed to Bypass Inverter when AC is available at Inverter Input.

In my particular configuration - whatever it is... with AC Power coming into the coach, Battery Chargers and all AC Breakers OFF I see Zero DC Load on batteries. Turning on Electric Fridge causes DC Load to increase to 30A.

Seems to me that AC for fridge and other outlets is coming from Inverter and draining batteries even though I'm plugged into CG Power.

I don't think Liberty is using the inverter transfer switches.

Gotta know how this works... it's really buggin me!

Lee

Lee
I know what you mean about it bugging you. If you have all the AC breakers off the only source for the power is from the inverter and batteries. What happens when you have the bus AC breakers on and the CG power plugged in? I am quessing that when you say AC breakers off you mean the ones in the buses main electrical panel.

I doubt your problem is with the transfer switches in the inverters, it is very unlikely for both of them to be bad and not passing AC thru.

In order for you to have power to the bus you have to have the buses AC breakers on, unless Liberty is really wired different.

The other thing you can do carefully is check for voltage coming out of the buses transfer switches and work towards the inverters, both input AC and output AC.

GregM

Just a piece of information about the automatic switching (at least in my vintage Liberty).

The way it has been set up, AC power defaults to the best source. In the absence of CG or generator power the switch allows the inverter power to pass into the AC circuit breaker panel.

If CG power is connected to the coach the relay closes so CG goes to the panel. If the generator is running, even if hooked up to CG power the transfer defaults to the generator in essence dropping the CG power off line and now generator power goes to the AC panel. This switching occurs because a relay "sees" power from a specific source and switches to provide that power source to the coach panel.

It is my understanding that if the inverter switches are "on" and in the case of Liberty coaches where the inverter battery charging circuit has its own dedicated AC circuit shore power flows to the refrigerator (for example) through a relay that closes essentially taking power away from the inverter. Because the battery charging portion of the inverter is separately powered it continues to function.

Greg:
When I said AC Breakers OFF I was referring to AC Distribution Panel Circuits not incoming AC.

Let me restate again. I have AC coming to Distribution panel from CG as I can turn on Air Cond, Water Heater, Battery Chargers and other "Non-Inverter Circuits". For simplicity these are all off.

Now, no Inverter Output AC Circuits are ON and Inverter panel shows no DC Load as expected.

Turn on Breaker for Fridge and DC Load goes to 30A approx which indicates to me that AC is not being passed through inverter. In this case it appears that AC is being produced by Inverter since we've got a DC Load being shown when Fridge is On.

I'm going to tear into inverters this week-end and see if Inverter Transfer Switches are being fed by AC from the outside world.

I'll let y'all know what I find out if I don't fry myself.

Lee

Quote:

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Originally Posted by hhoppe

Being new to the electrical nightmare of owning a Liberty I have to ask a dumb question. Is there an electrical schematic that the converter electrical techs follow when wiring the coach. Somehow I think the converters owe us a complete explanation of the above questions you have previously expressed. A series of color coded schematics showing the on and off circuits during each position of switches would be helpfull. Gary D get on this will ya.

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Liberty, I believe has designed the inverter system much like a UPS system in a office. If power fails you will automatically be switched to Battery power. That Battery power has a limited time value depending on what is on. For the most part, this is determined by the circuit breakers listed as being inverter controlled. However, there is 3-5 amps @ 120volt of parasitic loads as well. So, there is not a by-pass because that would leave the 120 volt circuits more vulnerable to outages.
All Liberty wiring is two wire with a hot and a nuetral. These are numbered at the start point(fuse or breaker) and at the end point(load). I don't know if I have schematics for this Coach but my previous Country Coach Lexa came with electrical and plumbing diagrams. I will look into it.

Lee
My coach has a circuit breaker for each inverter on the main AC panel. So I only have one wire leading into the each inverter. The "invert and charge" functions are controlled by each inverters remote. Look at the different wiring examples in the Heart manual and determine which diagram matches what you see in your coach. Maybe the AC breaker for "battery charger" is really the main supply for the inverters and incorrectly labeled. So instead of having two AC circuits going into the inverter (pass thru and charge) you have one input lead and the inverter either directs some AC to pass thru and some to charge. look at your inverter and see if you have two romex inputs and one output to the inverter AC subpanel or are there only one romex input and one output. As you will see in the manual it can be wired both ways.

I keep my loadsharing at minimum level so most AC is passed thru and the charge at a mimimum.
GregM

Eureka!! I have the answer!

Looked at the wiring on Inverters (I have two). Each one has Two AC Inputs - One for Charger and one for Transfer Switch. On each inverter these are tied together and protected by the breaker on my power panel labeled "CHARGER".

If I turn off both CHARGER breakers I have no AC going into Transfer Switch and inverter reverts to INVERT mode thus drawing DC amps from batteries.

Both chargers supply same bank of batteries.

To make thing worse, I'm in a CG with 30A power so, I turned off one CHARGER to keep from blowing breaker. By doing so, there was no AC being supplied to one inverter so it was drawing power from batteries and other inverter was passing AC via Transfer but also charging batteries so I saw DC load on Both inverters. One as a drain and the other supplying charge current.

In conclusion.. with fully charged batteries and both "CHARGER" breakers ON my DC load is near Zero when running MicroWave, Coffee Pot, TV, Fridge and more.

I'm a happy camper now that I know how things work.

Ain't knowlege wonderful?

Lee

Lee, we couldn't have done it without you. :D

Glad you got her figured out. :)

Now that you got that problem solved, what happend to your signature file and avatar? :confused:

Gary S

Gary:

Moved to new computer and forum didn't recognize me. Had to create new Login and forgot about signature file. Never had Avatar - maybee will do something this week-end about it.

Regards,

Lee
(no signature file for now - wife says we can't afford it!)

Way to go Lee, I'm saving a copy of your results for future entanglements with the Liberty.

Harry

I'm joining this thread very late. Hope someone is monitoring it. Or, this could move to a new thread.

We've been full time for a couple of months now and the electrical is still a puzzle. I've set up power sharing (took a month to even find out that (I think) it means power available to charge batteries) for 25 amps on one inverter and 5 amps on the other. When we have 50 amps shore power, all is well and we get by fine. This week we have 30 amps. So, for this 30 amp situation, if I turn off both inverters at the remote panel, it seems I get all 30 amps (sometimes more?) to use. The batteries don't seem to get used or charged, so their voltage seems to stay steady.

A curious thing that I do not understand is that when the inverters are on at the remote panel and I turn off the battery charger breakers, then there is no shore power coming through, though the circuits that the inverters can power still work.

Much is still not understood.

Any one interested in any more discussion on this?

Thanks. I sure enjoy all the help here.

Quote:

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Originally Posted by VegasDogMan

Eureka!! I have the answer!

Looked at the wiring on Inverters (I have two). Each one has Two AC Inputs - One for Charger and one for Transfer Switch. On each inverter these are tied together and protected by the breaker on my power panel labeled "CHARGER".

If I turn off both CHARGER breakers I have no AC going into Transfer Switch and inverter reverts to INVERT mode thus drawing DC amps from batteries.

Both chargers supply same bank of batteries.

To make thing worse, I'm in a CG with 30A power so, I turned off one CHARGER to keep from blowing breaker. By doing so, there was no AC being supplied to one inverter so it was drawing power from batteries and other inverter was passing AC via Transfer but also charging batteries so I saw DC load on Both inverters. One as a drain and the other supplying charge current.

In conclusion.. with fully charged batteries and both "CHARGER" breakers ON my DC load is near Zero when running MicroWave, Coffee Pot, TV, Fridge and more.

I'm a happy camper now that I know how things work.

Ain't knowlege wonderful?

Lee

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