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Old 10-14-2016, 12:05 PM   #11
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Originally Posted by chriscowles View Post
I'm under the impression that DC doesn't like distance. It degrades the available power. Isn't that why Westinghouse won out over Edison?
Distance is the enemy of current, not voltage. The only difference between AC and DC at the same voltage is that it is easier to change the voltage of AC (transformers don't work on DC) to a higher voltage to reduce the current, and back to a lower voltage to reduce hazards.

The 12V DC standard for vehicles is really obsolete now - it should be, and probably will be raised to 24V or higher (I've heard 40V is under serious consideration) in the not-too-distant future. 12V became the almost-universal vehicle standard in the 1960s - before then 6V, 8V, 12V, 24V, and 32V were all common vehicle voltages.

The reason for the need to change is the huge increase in demand for electricity in our vehicles. My 1986 higher-end pop-up had only lights, heater fan, and the brakes that used electric. The water pump was manual - there was a single faucet at the sink. Ice chests were used instead of fridges in most PUPs and many TTs of the era. There was no propane/CO/low voltage alarm - you cracked the roof vent when you used the inside stove, and sniffed for propane.

Cars had no computers, and power window and locks were a rare and high-priced option. If your generator/alternator quit, you turned off your lights and radio, and you could run for a long time with the just the ignition taking a little battery power. Gauges and fuel pumps were mechanical, and dash lights were not needed during the day. I had to learn hand turn signals (which were quite legal) as part of my drivers ed and license written test. My 1960 MG had windshield wipers and turn signals operated by engine vacuum.

It's a whole different world today, where even a pop-up has a 30 amp shore feed and converter, 120v outlets, and 6 separate DC circuits. And we add inverters to provide additional loads. A 300 watt inverter takes 25 amps of 12VDC when it's being used near capacity. 25 amps needs 10 gauge wire or better to avoid too much loss in the wire. Nothing in your house draws 25 amps except the A/C, electric clothes dryer, electric oven.

If a household appliance is going to take more than about 13 amps, it is typically made as a 240 volt item to reduce the current (and the required wire size). This ensures it gets it's own wiring from the panel, and it's own circuit breaker.

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Old 10-14-2016, 03:33 PM   #12
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Originally Posted by ependydad View Post
I bought an inverter off of the classified ads here (Xantrex PROwatt SW 1000) and now am trying to sort out how I want to use it.


  • My want is first and foremost to be able to run my CPAP/BIPAP machine in my bedroom. This is directly above my battery area where I'll install this inverter. Being able to run the TV in that room wouldn't be a bad thing as Momma and I like to wind down a little at night with some stupidity.
  • My second want is to be able to power my TV in the living room.
  • And finally, my 3rd want is to be able to run my dorm fridge in my outdoor kitchen (at the very back of the camper) while I'm driving down the road.

I probably should have bought a more expensive inverter that I could run hard-wires off of. But, this was a great deal and I now own it. So, help me out. Any ideas for how I can implement this thing?
I ran a cigarette type plug directly from my battery with a fuse in between next to my bed. Since DC has more voltage drop on long runs I used 14 guage wire just to make sure my CPAP is not under powered. That way I don't have to use extension cords. If you use an inverter to power the CPAP that uses extra energy that you really don't want to waste. An inverter must be wired very close to the battery with 6 or 8 guage wire.
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Old 10-14-2016, 06:19 PM   #13
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inverter

I just did this project a couple of months ago. Although I did not need to run a CPAP I did want to run the two TVs we have in our 5th wheel. Sounds like you also have a 5th wheel. I was able to mount the inverter just behind my batteries in the through storage compartment. I ran the two battery cables through the partition wall to the batteries. I then ran a separate circuit to three 15 amp outlets throughout the rig. One near the kitchen, one near each TV. I used 12 gauge heavy duty outdoor extension cord instead of Romex to run this circuit to each outlet. The heavy duty sheath of the extension allowed me to snake the wire through the underbelly without removing the three underbelly panels. I used regular cut in outlet boxes for the outlets and one 3 inch round box for a "J" box. I also used wire management hooks etc. to cleanly mount the wire to framing in the storage compartment. The remote on off switch for the inverter was easily mounted under our control panel. I did not want to bother with a transfer switch. I wanted to keep this project as simple as I could. Besides my main panel was at the far end of the rig.
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Old 10-14-2016, 06:36 PM   #14
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OK ependydad, you have a good start and a good inverter, now all you have to do is install it correctly. This may solve a little involved, but trust me, you will love it and it will do exactly what you need. I did this on my Georgetown 335 and it is probably the best thing I ever did. You have to do a real factory installation, not an after market add on. Here is what you need to do.

1) Plug into shore power and look at your power panel. You will probably find two 15 amp breakers for outlets, one for the GFIs (galley, bath, outside) and the other for the rest of the plugs. On my unit the one for the non-gfis powers all of the outlets in the bedroom and on the driver side of the coach. It also powers the bedroom TV and the living room TV. You can find out what you will get by turning it off to see what goes off.

2) Buy a Xantrex automatic transfer switch https://www.amazon.com/Xantrex-Inlin.../dp/B004S5Y158 You should be able to get it for 40 to 50 dollars.

3) from the breaker box find the wire that runs from the outlet breaker to the outlets and install an octagonal electric box and the two stripped leads from the transfer switch.

4) locate the inverter within reach of the plug on the transfer switch or run a good 12 gauge extension cord from that plug to the location of the inverter. This line is 120 volt and will not be subject to significant voltage drops, especially since it is 12 gauge.

5) plug it into the inverter and connect the DC side and fuses to your battery bank.

6) run the remote on/off switch to a convenient location.

Now, when you apply shore power or generator power, the transfer switch will automatically drop out and the inverter will idle (of course you can turn it off if you want to.) When the shore power drops or the generator is turned off, the outlets will automatically be powered by the inverter.

On my rig, which has both a rear converter and a rear power cable, the drop from the power panel was straight down and I powered the inverter by piggybacking it onto the converter output lugs (with a 100 amp fuse.)

Trust me...it is almost like they designed the RV to do this and there are no cords and no switches to throw. It is perfect and effortless.
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Old 10-14-2016, 08:09 PM   #15
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Originally Posted by tahoe1840 View Post
..I did not want to bother with a transfer switch. I wanted to keep this project as simple as I could. Besides my main panel was at the far end of the rig.
You now have a separate set of outlets that work on the inverter and a set that work on shore or genny power. The transfer switch is nothing compared to adding a bunch of single purpose outlets. If the factory did it that way you would be complaining.
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Old 10-14-2016, 08:19 PM   #16
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As a retired electrician, I believe I can shed some light on the DC vs AC situation. It isn't that DC does not like distance, but that the DC power must be generated at the voltage at which it is expected to be used. (Yes, there are alternatives in the 21st century) The problem lies in voltage drop, to minimize such requires larger and larger wire, depending on distance and current draw. With AC however, you can use transformers to increase the voltage to a very high level, which will allow you to move it for long distances over relatively small wires, then drop it down with another transformer to a level appropriate for use. With DC, transformers do not function. They will merely overheat to the extent of destruction.
Hopefully this puts a little light on the subject!
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Old 10-14-2016, 09:54 PM   #17
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Originally Posted by pgandw View Post
Distance is the enemy of current, not voltage. The only difference between AC and DC at the same voltage is that it is easier to change the voltage of AC (transformers don't work on DC) to a higher voltage to reduce the current, and back to a lower voltage to reduce hazards.

The 12V DC standard for vehicles is really obsolete now - it should be, and probably will be raised to 24V or higher (I've heard 40V is under serious consideration) in the not-too-distant future. 12V became the almost-universal vehicle standard in the 1960s - before then 6V, 8V, 12V, 24V, and 32V were all common vehicle voltages.

The reason for the need to change is the huge increase in demand for electricity in our vehicles. My 1986 higher-end pop-up had only lights, heater fan, and the brakes that used electric. The water pump was manual - there was a single faucet at the sink. Ice chests were used instead of fridges in most PUPs and many TTs of the era. There was no propane/CO/low voltage alarm - you cracked the roof vent when you used the inside stove, and sniffed for propane.

Cars had no computers, and power window and locks were a rare and high-priced option. If your generator/alternator quit, you turned off your lights and radio, and you could run for a long time with the just the ignition taking a little battery power. Gauges and fuel pumps were mechanical, and dash lights were not needed during the day. I had to learn hand turn signals (which were quite legal) as part of my drivers ed and license written test. My 1960 MG had windshield wipers and turn signals operated by engine vacuum.

It's a whole different world today, where even a pop-up has a 30 amp shore feed and converter, 120v outlets, and 6 separate DC circuits. And we add inverters to provide additional loads. A 300 watt inverter takes 25 amps of 12VDC when it's being used near capacity. 25 amps needs 10 gauge wire or better to avoid too much loss in the wire. Nothing in your house draws 25 amps except the A/C, electric clothes dryer, electric oven.

If a household appliance is going to take more than about 13 amps, it is typically made as a 240 volt item to reduce the current (and the required wire size). This ensures it gets it's own wiring from the panel, and it's own circuit breaker.

Fred W
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
Probably a good thing your MG had vacuum operated wiper. If they had been run by Lucas systems, they probably would have died.

In fact as the joke goes "Do you know why Brits drink warm beer? They didn't have Bosch components in their refrigerators". Okay, Okay, I drove a seized MG for an undercover narcotics car for awhile so sometimes I can't help myself!

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Old 10-15-2016, 09:59 AM   #18
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blisten to ScottBrownstein. Higher voltage drop on DC? it isn't that DC hates us. Its all about the amps traversing a length conductor ... both AC and DC are practicaly the same, at least for our RV purposes. Bottom line ... keep DC conductors as short as possible and make the longer AC feeds as long as you need to.. naturally you need to know how to size both correctly or hire an expert and do not burn down your RV to save a dollar
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Old 10-15-2016, 11:02 AM   #19
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Originally Posted by ScottBrownstein View Post
OK ependydad, you have a good start and a good inverter, now all you have to do is install it correctly. This may solve a little involved, but trust me, you will love it and it will do exactly what you need. I did this on my Georgetown 335 and it is probably the best thing I ever did. You have to do a real factory installation, not an after market add on. Here is what you need to do.

1) Plug into shore power and look at your power panel. You will probably find two 15 amp breakers for outlets, one for the GFIs (galley, bath, outside) and the other for the rest of the plugs. On my unit the one for the non-gfis powers all of the outlets in the bedroom and on the driver side of the coach. It also powers the bedroom TV and the living room TV. You can find out what you will get by turning it off to see what goes off.

2) Buy a Xantrex automatic transfer switch https://www.amazon.com/Xantrex-Inlin.../dp/B004S5Y158 You should be able to get it for 40 to 50 dollars.

3) from the breaker box find the wire that runs from the outlet breaker to the outlets and install an octagonal electric box and the two stripped leads from the transfer switch.

4) locate the inverter within reach of the plug on the transfer switch or run a good 12 gauge extension cord from that plug to the location of the inverter. This line is 120 volt and will not be subject to significant voltage drops, especially since it is 12 gauge.

5) plug it into the inverter and connect the DC side and fuses to your battery bank.

6) run the remote on/off switch to a convenient location.

Now, when you apply shore power or generator power, the transfer switch will automatically drop out and the inverter will idle (of course you can turn it off if you want to.) When the shore power drops or the generator is turned off, the outlets will automatically be powered by the inverter.

On my rig, which has both a rear converter and a rear power cable, the drop from the power panel was straight down and I powered the inverter by piggybacking it onto the converter output lugs (with a 100 amp fuse.)

Trust me...it is almost like they designed the RV to do this and there are no cords and no switches to throw. It is perfect and effortless.

This sounds like the best solution. Having most of the outlets hot scares me: my concern is training my kids (and monster-in-law) as to power savings when we aren't on shore power. Single battery and no generator to recharge makes me nervous. But, I do like the model/design.

Lots to think about- thanks to all who responded.
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Old 10-15-2016, 12:02 PM   #20
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.. Single battery and no generator to recharge makes me nervous. But, I do like the model/design.
Oops, that is pretty marginal. A CPAP with the humidifier turned off draws about 50 watts, which is maybe 4.5 amps at 12 volts. Throw in a hundred watts for the TV for or 4 hours and you are going to draw down pretty fast. No generator and only charging via the TV will have a hard time replacing that in a reasonable time. My rig is a class A with 4 12 volt deep cycles and a residential reefer. Most of the time I end up using the inverter for the CPAP and a satellite receiver and a TV. Of course, when driving on the road it really doesn't matter since my alternator supplies more than enough power to offset any inverter use.

I would consider adding another 12 volt battery when you install.
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