Inverter Transfer Function

[Jon Wehrenberg]

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.

[VegasDogMan]

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

[Jon Wehrenberg]

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.

[Just Plain Jeff]

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.

[Jon Wehrenberg]

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.

[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.

[dalej]

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.

[gmcbuffalo]

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

[VegasDogMan]

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

[gmcbuffalo]

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