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Old 05-03-2012, 12:20 AM   #11
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Originally Posted by rkswyo View Post
A dumb question for you guys. Could you mount the inverter in a handy location and plug the shore power cord into it?
I think I know what you are asking.

You want to hook your camper's shore power cord through a 30->20 amp adapter and plug it into your inverter in order to power your 120 volt ac camper items off your battery; right?

Sure!

Lets see how big an inverter you would need. 30 amps times 120 volts equals 3600 watts, No Problem! They make those!

Now how much battery bank do I need?

3600 watts divided by 10.5 volts (low battery cutout) = 350 amps

How long will the standard 75 amp hour battery last trying to deliver 350 amps? This is actually more complicated that it sounds.

From this graph you can see that the bigger the amp demand, the less capacity a battery has. Say for sake of argument your 75 amp hour battery was even capable of delivering 350 amps without melting (it can't BTW). And further it can somehow manage 25% of capacity at that draw (which it won't get that high). 25% of 75 AH equals 18.75 AH

How many hours will the 18.75 AH battery last trying to deliver 350 amps?

0.05 hours or about three and a half minutes.

We won't get into the converter trying to charge the battery with the battery.
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Old 05-03-2012, 12:31 AM   #12
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Where do you come up with 30 amps? I would not run microwave, converter or air conditioning off of it. Just tv and dish reciever. Just seemed like it would work and was curious. I guess from your response it was a dumb question.
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Old 05-03-2012, 12:50 AM   #13
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Originally Posted by rkswyo View Post
Where do you come up with 30 amps? I would not run microwave, converter or air conditioning off of it. Just TV and dish receiver. Just seemed like it would work and was curious. I guess from your response it was a dumb question.
I reread that and I realize I came off pretty flip. It is late and I totally apologize.

In fact, I actually thought of doing that at first myself until I examined it further. I should have just said "Bad idea" and left it at that.

Again I am sorry.

The real show stopper is the converter and the fridge (which will switch to AC heater if it "sees" 120 VAC) unless you remember to switch it to GAS only. The converter will see the low battery and try to charge it with the inverted battery power. If your camper has a seperate AC circuit for the converter you could switch it off. In my camper that breaker kills power to the entire entertainment suite as well.

You will also have limited control over what gets plugged into the camper's outlets (like transformers for cell phones, etc) all of which will be stealing your limited battery capacity. Hitting a switch by accident could destroy your battery's remaininig capacity and result on a "no heat" night.
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Old 05-03-2012, 01:04 AM   #14
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I didn't figure it was the best way to do it but taking the precautions you mentioned thought it could be done. A couple guys and I were talking about this at work the other day.
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Old 05-03-2012, 01:34 AM   #15
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normal appliance amp draws

when on shore power you have about or should have 30 amps available .
If your plugged in with a 20 or a 15 amp with adapter you should have that available.
look at the list and start adding up what you can and cannot run with the available amps.
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Old 05-03-2012, 09:25 AM   #16
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I didn't figure it was the best way to do it but taking the precautions you mentioned thought it could be done. A couple guys and I were talking about this at work the other day.
If you plan on doing this, (I still do not think it is a good idea) you will need to find the circuit protection for your converter and switch it off. Closely monitor every AC item to make sure it remains off; unless you need it on.

I used a heavy duty extension cord from the inverter outlet right to the TV area using a Surge Strip at the end. This gave me control on what was HOT at any given time. Now I have a Duplex there that is connected to the inverter, but still use the surge strip method. 150 AH does not last long running off the inverter to power the TV and our computer that contains our movie collection, as well as, all the DC needed to run the DC items like lights, sound system, and still have a battery to run the heat if needed at night (We get about 2-3 hours of TV in the evening if we will be needing the furnace to last till morning). Adding all the parasite AC loss by "Hotting" up the entire camper through that giant cord will most likely cut that some more.
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Old 05-03-2012, 09:55 AM   #17
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Herk your set up is solid!

So if I understand correctly, the picture with the five wall plates; is the inverter outlet the only direct connection to your inverter? Then you plug in the power strip for use when boondocking off the inverter?
That inverter outlet is hardwired to the inverter & batteries and the wiring runs under the TT belly (but enclosed)?

If I'm missing something, please clearify.

Did you do away with your plywood based circuit board or is that how the batteries and inverter were tied together? Which area in your TT houses that? It seems large, but that could be misleading from the photograph. I am trying to imagine where in the front I could place a similar setup without it getting digged up from stowwing other items while traveling. I asked my neighbor yesterday about this but he only uses puplic campgrounds and thought I was nuts. So I'll leave out of further discuissions
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Old 05-03-2012, 02:01 PM   #18
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Joeyo, I camp about 95% of the time in BLM or Nation Forest areas. Mostly just me and the misses. Water is our biggest problem. I’m running a 2400 gen so electricity is not an issue. Over long weekends its always the darn grey that gets close, and I never dump grey in the woods. We do dishes and take quickie showers and I take about 20 gal of water with us. (my tanks are 50 fresh 30 and 30). With a group of 6, I’m thinkin your black and grey will fill up. I do have a folding toilet seat so in a pinch I can dig a cat hole, but usually dont need it. Think it was $30 at walmart and stays in the camper. Guess my only suggestion is an additional/portable dump tank and try and keep the showers to a min. Have fun!
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Old 05-03-2012, 02:18 PM   #19
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The Electrical upgrade was done when the camper was about a week old. It was also before I "photo documented" what I was doing.

I put a 3/8 inch plywood "wall" between the forward compartment and the main compartment. I did this to separate my tools from the battery compartment and added a second battery before there was more than a couple of cycles on the old one.

As to how I use my inverter and the Duplex you are exactly correct. The only thing we use our inverter for is the computer; TV; and Phone Chargers. We move the strip plug from one to the other depending on whether we are boondocking or not.
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Old 05-04-2012, 09:25 AM   #20
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I agree with everyone else that water will be your biggest issue, especially with 6 people and a dog. To extend your range, I would recommend an auxiliary dump tank and a pair jerry cans with water.

The other way to minimize water usage are paper plates, cups, eating utensils; they don't need to be washed.

Power
I disagree with the use of inverters. These devices are power hogs and will inhaled battery power. Bigger only gets moves you from a power piglet to a power hog.

What is wiser is to keep as many appliances as possible as 12 volt units. There are exceptions. Most devices rely on at least DC, and it is usually more efficient to DC appliances on DC than converting to AC and back again to DC.

Having a fused DC bus is a pretty good idea. There are plenty of 12 volt fans, LED and flourescent lights that run on 12 VDC. If you can keep as many of your essential toys on 12 VDC all the better.

As indicated, you will need a minimum of a Yamaha 2400 inverter style genset to a 13.5 KBTU A/C, at least a 3KW to power anything larger.

Let me add that the contractor grade 2400 watt gensets are iffy on 13.5 A/Cs. The reason for that is the way the gensets operate. The inverter style have the correct voltage and frequency, so the A/Cs have an easier time start on those.

Anyway, we will probably boondock down to the power level 20 days this year. Boondocking on water alone about 24 days. My present trailer is not as frugal on power as the old TM was (too many incandescence lights), but I will be improving it over the year.
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