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Proper inverter practice?

Until this week our inverter was mostly along for the ride. IF weather was such that I didn't need to run anything else on the road I'd sometimes turn the inverter on, but it is off for the most part. Saturday afternoon a thunderstorm came through the park and knocked out the electricity. Generators are permitted until 10 p.m. and power didn't come back until 12:15 or so, so I turned the inverter on to keep the refrigerator going. Sunday morning I turned it off again. Today someone hit a power pole and we've been without electricity since 11:30. Ameren guesses it will be back about 10 tonight. In talking to the other hosts it seems that power goes off frequently here, with outages lasting 10-12 hours.

Should I just leave the inverter on? It powers only the refrigerator and microwave, but even when we're plugged in, running the microwave causes the 12v lights to blink a bit.

Re: Proper inverter practice?

Reply #1 –
David,

After we upgraded our OEM modified sine inverter to the Magnum MS2812 (in 2015) we just got in the habit of leaving it on all the time.  We already had a a residential fridge when we made the inverter upgrade, so by leaving the inverter turned on I knew the fridge would always have power.  Never have had a bit of trouble from the inverter, so I guess it didn't mind being constantly on.  It does use some battery power when in "standby" but I never found that a problem.  The fridge (Samsung) on the other hand recently died.  So for now our inverter is turned off unless we want to run the microwave or the big screen TV, but the battery charger function is always turned on.

When you are plugged in, the shore power should pass straight through the inverter (if it works like ours) to power your 110V appliances.  Or perhaps your coach is still wired so you have to select between inverter and shore power?

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Proper inverter practice?

Reply #2 –
My Xantrex 3012 has been turned on since 2015 even in storage at the house. I don't think it is a time hour life but a power usage life
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Proper inverter practice?

Reply #3 –
David,

What inverter/charger do you have?
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Proper inverter practice?

Reply #4 –
There are two 60A 4-stage converter/chargers and a 2000W Pure Sine Wave inverter. I don't remember the brand of the converter/chargers, but the inverter is a Samlex (spelling?).








Re: Proper inverter practice?

Reply #5 –
The problem comes into play if the inverter is left on and the power goes out you may not know you are running on the batteries. If the power is out for a long time you will be running your batteries down. 

We were parked in a campground and our 50 amp breaker at the pole tripped.  We never knew it since since the inverter keep powering the TV and all.  It was not until my wife was warm and went to turn an AC on. As soon as she did that the generator started.  That surprised both of us. I started trying to figure out why generator started and finally figured out the 50 amp breaker had tripped.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Proper inverter practice?

Reply #6 –
David,

If your 12V lights flicker when the MW is on and you are on shore power, you have a wiring deficiency somewhere between the pole and your outlets. We have exactly the same coach and ours never flicker. Both ACs work fine at the same time if the cord from shore power to the coach  is sized for the load. You are not using the 50 amp cord are you?

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Proper inverter practice?

Reply #7 –
Yes, we're on 50A shore power. Both air conditioners are on, inverter is on. Jo Ann just turned on the fry pan to start making lunch and the lights blinked once when it came on. They didn't go all the way off, just a quick dim and back up. The inverter has a switch on the wall that lets me select either the microwave and refrigerator OR the ice maker, blender, and tv. The ice maker is long gone, there never was a blender, and the tv is off. I've got the inverter switched to that position.

The temperature is supposed to get cool enough tonight that we can turn the a/c off and open windows. I'm going to switch the inverter back to the refrigerator position when we go to bed just in case the power goes out. Jo Ann suggested that we just go back to leaving it off unless we need it, but I'm not thrilled about going outside in a thunderstorm to turn the inverter on.

Re: Proper inverter practice?

Reply #8 –
I would go and check all your wiring, to make sure you don't have a loose connection.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Proper inverter practice?

Reply #9 –
Quote from: kb0zke –
Yes, we're on 50A shore power. Both air conditioners are on, inverter is on. Jo Ann just turned on the fry pan to start making lunch and the lights blinked once when it came on. They didn't go all the way off, just a quick dim and back up. The inverter has a switch on the wall that lets me select either the microwave and refrigerator OR the ice maker, blender, and tv. The ice maker is long gone, there never was a blender, and the tv is off. I've got the inverter switched to that position.

The temperature is supposed to get cool enough tonight that we can turn the a/c off and open windows. I'm going to switch the inverter back to the refrigerator position when we go to bed just in case the power goes out. Jo Ann suggested that we just go back to leaving it off unless we need it, but I'm not thrilled about going outside in a thunderstorm to turn the inverter on.
OK, got it that you are on shore power but why is the inverter on if you are on shore power? Do you have the big black Taytronics OEM inverter? They are super reliable but huge power hogs even with no load on them. Plus, they weigh almost as much as an 8D battery. Have you replaced your interior lights with LEDs?

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Proper inverter practice?

Reply #10 –
David,

What you have is a basic inverter, not an inverter/charger.

If you can run your microwave on inverter power (in absence of shore power or generator), it is taking a huge amp draw from the house battery bank, so, yes the lights will dim.

Rather than  a "pass through" feature built into your inverter, your second ATS selects for 120 VAC from shore power or generator when present.

Most inverters are more complex-- with "pass through" feature built in, as well as charging capabilities, etc.

If you are in one place on shore power for a long time, please verify that your second ATS is working on shore power not inverter.

Yes, another (but expensive) option would be to get a "full feature" inverter/charger.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Proper inverter practice?

Reply #11 –
Brett,

He has a 1993 U300 like ours but 40 feet. The OEM inverter was located in the starboard side compartment by the mid entry door. The converter/charger is on the other side (on ours) right by the big electrical panel next to the wet bay.  Our new inverters occupy the same location as a large 12V cable is right there.

I modified the transfer relay switch box wiring under the bed and eliminated the switch on the galley wall by the sink so our main inverter runs circuit #2 and #5 together. I do have to make sure not to run the MW and TV, outlets, etc at the same time.

I have photos of the modification of the transfer relay box if anyone is interested.

For newbies, the Foretravel forum has a ton of information, diagrams, schematics, etc available and only a click away. Rather than explaining how to navigate there, see attachments below.

When on shore power, the inverter(s) should be off and the shore power will run everything and charge the house batteries at the same time. When you disconnect from the shore pole, the inverters can be turned on and will power some of the circuits, #2 and #5 on our U300.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Proper inverter practice?

Reply #12 –
Thanks, Pierce. "When on shore power, the inverter(s) should be off and the shore power will run everything and charge the house batteries at the same time." That's exactly what I was asking.

Yes, the old Taytronics inverter is long gone. The new Samlex is in the same place. It is ONLY an inverter, not an inverter/charger. As Pierce said, the charger/converter pair (I have two, wired in parallel) are in a different bay altogether. The inverter is in the smaller bay, under the steps. It isn't too hard to access the switch, so that's why it was usually off. The converter/chargers are in the big bay on the driver's side. There were two, wired in parallel, so that's what I bought nearly 10 years ago when I replaced the Taytronics and the converter/chargers. Knowing what I know now I probably would have been smarter to buy a single unit and mounted it where the two are now.

I think the plan going forward will be to leave the inverter off unless I suspect that we may need it. The inverter came with a remote switch that works for turning the unit off, but I haven't figured out how to turn it on that way.

I mentioned turning the inverter on when I suspect that I may need it. Yesterday's 8-hour power outage was due to someone failing to make a turn and taking out a power pole. Apparently that pole gets replaced a couple times each year because of similar driving. Not sure how one plans for such outages.

Re: Proper inverter practice?

Reply #13 –
Pierce/David,

So, with no internal "pass through feature", assume you have a second ATS to select shore power vs inverter for the microwave and anything else in the inverter circuit.

Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Proper inverter practice?

Reply #14 –
With mine, when the inverter is OFF, shore/generator power flows normally. From what others have said, when my inverter is ON those circuits may be powered by the inverter rather than shore power. Now that you mention it, I think there might be a second ATS under the bed. I'll check the next time I need under there.

Apparently I didn't have the remote plugged in all the way before. When I plugged it in and tried it just now, it turns the inverter on and off. I'm trying to figure out it I can mount that little box up here somewhere without disassembling the whole coach. I opened up the little pony wall by the steps because there are wires that go down to the basement from there. They run through a square steel tube. From the basement side it looks like they use a piece of ½" plastic tube as a conduit. That isn't big enough for the remove cable to go through, but maybe I can drill another hole next to it and come up that way.

Re: Proper inverter practice?

Reply #15 –
Brett,

No, I modified it so it works just like it did before but instead of having two different circuits, I've just combined #2 and #5 so, just no switch on the wall but other than that, you never notice the difference. Now, I have to find the old photos.  >:(

I think I made a little jumper and one other change but while it took a hour or so to figure out, it can be repeated in 5 minutes.e

David, the momentary contact with the existing switch on the inverter turns it on but also off. The same is true for a couple of wires to a remote location or a wireless switch. It's just a momentary closing the contact. Like a latching relay.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Proper inverter practice?

Reply #16 –
Quote from: kb0zke –
With mine, when the inverter is OFF, shore/generator power flows normally. From what others have said, when my inverter is ON those circuits may be powered by the inverter rather than shore power. Now that you mention it, I think there might be a second ATS under the bed. I'll check the next time I need under there.
Like below to Forum library document showing dual OEM 110V switching relays like originally used on our '93 model U280.  U300 similar?

https://www.foreforums.com/index.php?action=media;sa=item;in=3267#viewitem

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"
 

Re: Proper inverter practice?

Reply #17 –
Could not find my old photos so I went out to the coach and snapped three. The transfer switch is located under the bed so just lift it up, put a stick in place and use a lantern of some kind to provide light.

A turn of so with Philips screwdriver will loosen the screws enough so you can slide it a tiny bit and lift it off. The schematic is on the back of the lid.

I pulled all the wires from the wall selector switch as well as removing the switch plate. Not a quick job as I ran new wires to the remote on/off switch and battery indicator for the inverter. This is from quite a while ago so my memory may not be exact. I started looking at the schematic, comparing it to the hardware. The 24 volts made me think for a second but then I realized  the little circuit board supplied the 24 volt so not to worry. Then, I noticed that Foretravel had changed one wire to a different terminal compared to the schematic but I can't remember which one. That one also stumped me for a few minutes. A little comparison of the schematic and the box will tell the tale. Then I thought some more and after getting the schematic memorized, I started installing a couple of jumpers. One is the white one in the photo and the other is red and black speaker wire I happened to have with me. I was going to put in another jumper that was a little neater but forgot. Now, I will change the black and red jumpers tomorrow.

It's amazing how much smoke from different places an electrical mistake can make... Shocking............Just kidding, it works fine. This is only what I did and I'm not recommending you copy it. If you do, make sure the shore power is off, inverter is off, etc, etc. Intermediate voltage like 110V is the most dangerous so check and dbl check there is not power there. Gloves and insulated driver are good. (do as I say, not as I do)

Now, our main inverter operates circuit #2 and #5 when it's switched on. But, not satisfied, I sent the juice from one of the other inverters directly to the MW. A sine wave inverter will speed heating by at least 300% compared to a MSW inverter.

I recommend installing a rotary switch for the 12V supply for EACH inverter. I case of a problem, it's easy to shut the inverter down, otherwise, you could have a problem.

I did some other wiring but can't remember now. Will take a look and post if important.

And if you are confused, the stock switch on the galley wall selects either relay A or B. Now both are actuated when the inverter is turned on.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)