Advantages of 12V when you have an inverter?

[buzz&jessie]

We've been perusing lots of threads and still haven't quite found what we are looking for. Since we know we will be ordering dual 6V batteries and the 1500 Watt inverter, we are not sure if we need extra 12V outlets inside or outside our 19' to be. If we are boondocking, is it less efficient to use 120V via the inverter than 12V directly (e.g. To power a CPAP which can be either)? If not, it would seem that 12V outlets would only be useful for dedicated 12V appliances: having not camped for years, are there such "must haves". Bottom line: we are thinking we only need one 12V outlet in and outside. But I see many posts with added 12V outlets in the overheads, etc. Are we missing something? Thanks!

[hotfishtacos]

Here are some examples where extra 12 volt outlets help.
> One under the dinette for charging phones, notepads, etc.
> One near the kitchen for running a 12 volt appliance
> One near the bed for charging phones, notepads, etc. Folks like the phone nearby when sleeping so this helps.
> One near the bed for a 12 volts fan(s) when hot. We use this one a lot.
> One outside to run small lamps or appliances under the awning.

etc, etc..the more the better...

[kstock11]

There is an "energy cost" to converting from 12V to 120V. When you are boondocking, you tend to try to squeeze every watt out of your batteries. My suggestion would be to look at what you carry and which can be charged by 12V. On our trip cross country from Chilliwack, we had 17 items needing occasional charges or power to run. Items that could be charged with 12V, were charged that way. (Things like laptop, ipod, iPhone, GPS, mp3 players)

[Brian B-P]

Originally Posted by buzz&jessie

If we are boondocking, is it less efficient to use 120V via the inverter than 12V directly (e.g. To power a CPAP which can be either)?

Yes, it is less efficient, due to more stages of converting power from one voltage to another. It can also mean some extra noise (if the inverter fan comes on).

The efficiency loss shouldn't be a big deal for low-power devices, but I still think fewer components is better - if I can charge a phone with one adapter in a 12V outlet instead of an inverter and a 120VAC adapter, I would rather go the simpler way.

[FMLNM]

If you are going to plug in CPAPs I would suggest you get 12v outlets where you will be using the CPAPs. For most CPAP machines you can get machine specific power cords that plug directly into 12v outlets.
We wired in 12v outlets in our rig ourselves so we could do that.

[fudge_brownie]

Good recommendation on running the CPAP via 12 volt. Depending on duration of use during the overnight hours and your air flow settings they can make a pretty good dent in your battery supply. Using less power here will help a great deal in battery conservation.



There are two reasons the 12 volt plug uses less power:

• The conversion factor as outlined above, essentially you are taking 12 volt from the battery then converting it to 110 volt via the inverter and then back to 12 volt (if your CPAP 110 power cord has a brick in the cord) for the CPAP. I have not seen that many CPAP machines, but those I have seen have all been 12 volt devices with an adapter to run off 110. There is a loss during this process.
• The second reason for using less power is that on most CPAP's running off 12 volt the device will automatically disable the reservoir heater. The air flow over the water supply will not contain as much moisture. This may be important to you and could result in some discomfort.

[LeonW]

This was one of the things we thought about when we ordered our last trailer. One of the pieces of advice that we got was "When it comes to inverters, go all in, or go home". That got me thinking about what we had that really required 120 volts. We already had several 12 volt converters for electronics. The TV and the DVD worked just fine on 12 volts. In the end we decided that we could get along just fine without any inverters at all, but ask for additional 12 volt outlets since we are never in the right place to charge our portable electronics. Your mileage may vary, but so far we have been happy with that decision.

[cpaharley2008]

Originally Posted by LeonW

This was one of the things we thought about when we ordered our last trailer. One of the pieces of advice that we got was "When it comes to inverters, go all in, or go home". That got me thinking about what we had that really required 120 volts. We already had several 12 volt converters for electronics. The TV and the DVD worked just fine on 12 volts. In the end we decided that we could get along just fine without any inverters at all, but ask for additional 12 volt outlets since we are never in the right place to charge our portable electronics. Your mileage may vary, but so far we have been happy with that decision.

That is exactly what I did, other than the air conditioning, I'm all 12volt. I had 5 extra installed during the build and ended up adding a 7th myself. I'm now wired for 12v bed heat pad for those overnight stays in rest areas. It shuts off in one hour.

[Vermilye]

Even when you use inverters to supply 120V, it may pay to have a couple of them. While the 1500 watt inverter will run almost anything, it has more losses than some smaller inverters. Using it to produce a few watts for low power devices may waste power.

Keeping a 100W to 250W inverter for small loads may provide longer battery life. As long as your battery side draw is under 10 amps, the standard cigarette lighter 12V receptacle will work with the small inverter so having a couple of them in strategic locations can be useful.

[buzz&jessie]

Thank you everyone for your timely responses, they helped make things clearer. Our build date is Jan.1, a great way to start 2015. Looking forward to meeting some of you in person at the May rally.

[skiman]

Originally Posted by cpaharley2008

That is exactly what I did, other than the air conditioning, I'm all 12volt. I had 5 extra installed during the build and ended up adding a 7th myself. I'm now wired for 12v bed heat pad for those overnight stays in rest areas. It shuts off in one hour.

Jim,
Where did you buy your mattress pad? You think it would work through the Travasak thin side?

We got the extra 12 volts like cphaharley. Glad we did. All 12 volt and works out well.

[cpaharley2008]

It is really just a 12v blanket which I put inside the Travasak. Amazon.com: MAXSA Innovations 20014 Comfy Cruise 12V Heated Travel Blanket, Plaid: Automotive

[Greggo]

Great discussion. I've been pondering 12v vs 120 for awhile. Not all inverters are created equal. Quality of power aside, does a cheap inverter take more energy to create 120v from 12v than a similar sized modified or full sine inverter?

[padlin]

If anyone runs across a queen size 12v blanket let me know.

[hotfishtacos]

Originally Posted by padlin

If anyone runs across a queen size 12v blanket let me know.

I thought about running a modified dryer hose from the heater output to under the blanket in the bed...about 4-5 feet. The heater has a high volume of air output and I'll bet it would warm the bed very quickly...so 12 volts runs the heater fan motor.

[LeonW]

Has anyone used one of the 12 volt crockpots on the market? I think it would be nice to find a small crockpot that could fit in side the sink and be plugged into the 12volt circuit while driving. That way there could be hot stew or a roast ready when you arrive in camp.

As I recall, there was once a cookbook for making recipes that cooked a meal on one's exhaust manifold. But in the newer models, it is hard to find the exhaust manifold. I am sure it is there, somewhere under the big plastic cover I see when I open the hood. And the quality of the roadkill just isn't what it used to be. So a crockpot is the next best alternative.

[StarvingHyena]

Rather than buy a relative expensive 12v crock pot, I'd just plug plug my 110v ac crock pot into a 12v - 110v inverter. Those inverters aren't expensive nd can allow you to use other mass marketed appliances. Just be sure to get one that can handle the required wattages.


I have done this for years as my cabin in Alaska has been off the grid for more than 15 years. A word of caution: The cooking times of many crock recipes can take the shine off your batteries without simultaneous battery charging.

[Jim Bennett]

Not sure I would want to travel with a crock pot on. When on the road, we plan quick and easy meals for travel day. Something with just a few minutes of cooking time, like a Caesar salad with grilled chicken. 5 minutes and we are eating.

[escape artist]

Originally Posted by Jim Bennett

Not sure I would want to travel with a crock pot on. When on the road, we plan quick and easy meals for travel day. Something with just a few minutes of cooking time, like a Caesar salad with grilled chicken. 5 minutes and we are eating.

Hi: Jim Bennett... Here's an easy solution. Add some Johnsonville Brats to a wide mouth thermos leaving a bit of space. Fill with boiling water, seal, and place it in the sink. Ready to eat when you are!!! Pass the mustard and relish. Alf
escape artist N.S. of Lake Erie

[gbaglo]

Originally Posted by hotfishtacos

I thought about running a modified dryer hose from the heater output to under the blanket in the bed...about 4-5 feet. The heater has a high volume of air output and I'll bet it would warm the bed very quickly...so 12 volts runs the heater fan motor.

Kinky.