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Old 02-18-2016, 03:50 PM   #1
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Brand: Thor Motor Coach
State: Alberta
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THOR #3672
Constant inverter failure because of bad xfer switch?

I have a new Thor 37tb and used it on one trip and all was good. Now is seems that about 50% of the time I use the generator while camping it will render the inverter useless. A friend thinks it's because of a bad xfer switch. Any thoughts pls
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Old 02-18-2016, 05:15 PM   #2
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Brand: Thor Motor Coach
Model: Miramar 33.5
State: Washington
Posts: 217
THOR #578
The purpose of the inverter is to invert DC power to AC power.
In this case the Inverter takes 12V DC power from your batteries and inverts it to 120v AC power. This allows you to run your residential fridge and if equipped an outside kitchen fridge while rolling down the road, or dry camping.

If you are parked with your inverter on, you can look at the Xantrex monitor panel and it will display what the volts on your 12V battery system is. There are three little indicator lights on the left hand side of the panel: Utility, Battery and Fault.

If you have the inverter on and plugged into shore power, the Utility light will illuminate. If you are plugged into shore power, inverter should be turned off, I don't think its really doing anything! (I guess you could leave it on as a fail-safe measure????)

If you are not plugged into shore power and are running the inverter to power the coach, then you will see the Battery light illuminated on the Xantrex panel. This indicates you are powering the Xantrex inverter through your 12V battery system and the volts displayed are an indication of your battery state.

The Fault light will illuminate if the system detects a fault somewhere!

If,,, while you are running the inverter and you start your Genny, the Genny will take over providing the AC power., it will also start charging your batteries. Also if you have your Magnum auto start system enabled, it will auto start Genny based on what parameters you set, (low volts/high temp in coach).

In the above scenario, if the Magnum auto start was set to run for two hours to recharge your batteries, after the two hrs, the Genny would shut down and the inverter would go back to providing AC power!
Hope this helps!
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Old 02-18-2016, 06:02 PM   #3
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THOR #3672
All the inverters that I've had installed (3 so far) seems to work fine until the generator starts up. After the generator starts up and charges batteries, works the AC, etc.. The generator shuts down and then 50% of the time the inverter no longer works. It does come up with an error code that is not a code listed in the manual but it just no longer powers the refrigerator or any ac powered devices. No breakers are tripped and all seems in order. When the motorhome is plugged into my home, 15 or 20 amp outdoor plug, every thing functions perfectly, and when I disconnect from my house the inverter has always been fine. So it is only ruining the inverter when the generator is used, and it does ruin the inverter when the generator does an "auto start" as well. I've even installed a different brand of inverter the last time and the exact same thing happens.
I don't know if it's a power surge when the generator is "starting" or just as it's coming online to supply power or if it is the charger coming online but only when under the power of the generator. Another thing to be aware of is that if I'm travelling a lot the inverter seems to be ok, it's only when I'm at a campsite with out power and I use the generator for the ac power. When I,m travelling I'm plugged in at campsites most of the time so I don't use the generator much unless we want to use the microwave while driving, if we do the batteries are fully charged and don't need a big charge when we start the generator so there's no surge or big blast of power at first start up....?
A friend of mine figures that the switch is bad and allowing a back feed when the genny is started. So I asked why not when I plug into land power? He says that the land power is pretty much a perfect match of volts and amps all the time but when a generator is use it is not as perfect for a slit second at the beginning and if the switch works properly it won't allow the "bad" mix of power (low voltage and high amps) to go anywhere but he figures the whole system is getting the bad stuff but the inverter is unable to handle it and it gets fried. Thoughts pls
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Old 02-18-2016, 06:17 PM   #4
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Brand: Thor Motor Coach
Model: Miramar 33.5
State: Washington
Posts: 217
THOR #578
Hmm, do you have the Furrion 50 amp relay?

On my Miramar 33.5, when I start the Genny, there is a slight delay, 4-5 seconds before the Furrion 50 amp relay kicks over. I wonder if there is an issue there? My relay is located in the same bay that my power cord is.

Defiantly sounds like you have a gremlin or stray Cheetos floating around in there!!

On a side note,,,

On my Onan 5500 gen, I have two 30 amp breakers, I wonder if you tripped those breakers before you started then Genny. After the Genny is up and running, bring those on one at time to see if one of them causes an issue?

Between those 30 amp breakers and the main 50 amp breakers, I would think they would catch a problem before it made it into the coach, which makes me wonder about the Furrion power relay???

Just thinking aloud!!
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Old 02-18-2016, 06:24 PM   #5
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THOR #3672
My Thor is put away for the winter and I'm unable to get to it until April and I don't know what brand of switch I have but I do know that it is 50amps and that it does switch very quickly. I wonder if they are all supposed to be delayed for 4-5 seconds before letting power through? Does the transfer switch theory I laid out sound plausible?
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Old 02-18-2016, 06:34 PM   #6
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THOR #578
I am by no means an expert, just based on my experience with my last three coaches, they all had the same set up, there will be a 4-5 second delay after the Genny stabilizes and the relay kicks over!

The power from the shore power and the Genny run through the Furrion box, then a single line runs from there to the main power panel under my bed. From there AC power is distibuted!

That Furrion relay may be a place to start!!
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Old 02-19-2016, 12:12 AM   #7
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THOR #2601
I don't have an inverter (have a Vegas) and I am a bit ignorant about its operation but I have a question. Why operate the inverter when you are running the generator? Is there a converter (with a charging circuit to charge the house batteries) or does the inverter charge the batteries? I ask because if there is a converter to convert the AC provided by the generator to DC for system operation and charging the house batteries?

It seems counter intuitive to use an inverter to invert DC power into AC when the generator is operating and providing AC current.

Pardon my ignorance about inverters -- but inquisitive minds would like to know.
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Old 02-19-2016, 12:50 AM   #8
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THOR #1150
Quote:
Originally Posted by bevedfelker
I don't have an inverter (have a Vegas) and I am a bit ignorant about its operation but I have a question. Why operate the inverter when you are running the generator? Is there a converter (with a charging circuit to charge the house batteries) or does the inverter charge the batteries? I ask because if there is a converter to convert the AC provided by the generator to DC for system operation and charging the house batteries?

It seems counter intuitive to use an inverter to invert DC power into AC when the generator is operating and providing AC current.

Pardon my ignorance about inverters -- but inquisitive minds would like to know.
That could be the problem: The auto crossover switch isn't working correctly and allowing the inverter to run with the genny thereby destroying the inverter.
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Old 02-19-2016, 03:58 AM   #9
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Brand: Thor Motor Coach
Model: Miramar 33.5
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THOR #578
Quote:
Originally Posted by bevedfelker View Post
I don't have an inverter (have a Vegas) and I am a bit ignorant about its operation but I have a question. Why operate the inverter when you are running the generator? Is there a converter (with a charging circuit to charge the house batteries) or does the inverter charge the batteries? I ask because if there is a converter to convert the AC provided by the generator to DC for system operation and charging the house batteries?

It seems counter intuitive to use an inverter to invert DC power into AC when the generator is operating and providing AC current.

Pardon my ignorance about inverters -- but inquisitive minds would like to know.
If you are dry camping, the inverter allows you to power your fridge with AC power, if the fridge has been running for at least a day and it and its content are good and cold, the fridge will not cycle on as much. Therefore the inverter through the batteries can power the fridge for up to 3 hours, depending on the quality of your batteries. Using the Magnum auto start, once the volts reach 11 volts, the auto start will turn the Genny on. At this point, the Genny will begin powering the fridge and through the converter/charger will start recharging the depleted batteries.

I have my auto start set to run for 2 hours, after two hours, the Genny will shutdown and the inverter takes over powering the fridge. This cycle will continue as long as there is enough fuel in the tank to run the Genny.

I find this useful if we stop while traveling, we stopped for about 4 hours taking a tour. I didn't want to leave the Genny running for 4 hrs. I left the inverter on, with the auto start enabled. The Genny came on when the volts dropped and it ran for 2 hours and shut down. I had annotated the hours on the gen before we left. It worked as advertised!
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Old 02-19-2016, 03:08 PM   #10
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Quote:
Originally Posted by JamieGeek View Post
That could be the problem: The auto crossover switch isn't working correctly and allowing the inverter to run with the genny thereby destroying the inverter.
I agree something doesn't sound correct. If the inverter has a transfer switch and it's wired correctly, it should never be powering anything in parallel with the generator or with shore power.

The discussion about the quality of the power coming into inverter from generator versus shore power left me wondering why it's even an issue at all. The inverter should either be online by itself or bypassed (to a given circuit if split).

Granted there are many ways to wire-in an inverter. I know some are installed to supply power to only a few outlets (like residential fridge), but even then there should be no way to connect power in parallel with inverter.

This is a good example of why I like simplicity. An inverter/charger with its own transfer switch should prevent many of these types of issues. Obviously, many loads like air conditioning would have to be turned off -- manually or automatically -- to prevent overloading the inverter and or batteries.
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Old 02-19-2016, 06:21 PM   #11
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Brand: Thor Motor Coach
State: Alberta
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THOR #3672
Quote:
Originally Posted by bevedfelker View Post
I don't have an inverter (have a Vegas) and I am a bit ignorant about its operation but I have a question. Why operate the inverter when you are running the generator? Is there a converter (with a charging circuit to charge the house batteries) or does the inverter charge the batteries? I ask because if there is a converter to convert the AC provided by the generator to DC for system operation and charging the house batteries?

It seems counter intuitive to use an inverter to invert DC power into AC when the generator is operating and providing AC current.

Pardon my ignorance about inverters -- but inquisitive minds would like to know.
I have enough house battery power to run the refrigerator using the inverter all night long. This will keep the campsite quiet at night for all. Basically the inverter and a bank of batteries will take the place of a generator for hours at a time. When you need more power for air conditioning etc you then start the genny or when your batteries are getting low you then start up the genny to charge them. Also the motor that drives the motorhome will also charge the house batteries while under way and the inverter will continue to supply power for the refrigerator etc without the need of running the generator. I would not enjoy our camping as much if I didn't have a good set of batteries and an inverter to take the place of the generator as much as possible.
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