How Many Watts Available In My 12v Outlet - Page 2

PineForestCamper · 05-08-2013, 03:38 PM

Multimeter not helpful. Ok. Is a multimeter ever helpful inside the RV and for what applications involving 12v and 110?

Also...walk me thru this...
So lets say I have a 15 fuse. I take the 15 x 12 and that equals = 180. That means I have 180 watts of available power. If I plug in a 100 watt bulb I now have only 80 watts of available power until I blow that fuse. Is that correct?

TURBS · 05-08-2013, 04:01 PM

Quote:

Originally Posted by WarMovies

Multimeter not helpful. Ok. Is a multimeter ever helpful inside the RV and for what applications involving 12v and 110?

Also...walk me thru this...
So lets say I have a 15 fuse. I take the 15 x 12 and that equals = 180. That means I have 180 watts of available power. If I plug in a 100 watt bulb I now have only 80 watts of available power until I blow that fuse. Is that correct?

100 watt 12v bulb?

I'm goin to have to read through these posts.

What is your ultimate goal here?

Nevermind I read your 1st post several times.

If I am getting this right ....
Why would you need to know wattage from your 12v outlet?
Your inverter or most portable inverters are internally fused.
But more importantly it will tell you minimum wire size needed to run inverter at capacity.
That's all you really need to know unless I'm missing something. ....

**wmtire** · 05-08-2013, 04:15 PM

Quote:

Originally Posted by WarMovies

Multimeter not helpful. Ok. Is a multimeter ever helpful inside the RV and for what applications involving 12v and 110?

Also...walk me thru this...
So lets say I have a 15 fuse. I take the 15 x 12 and that equals = 180. That means I have 180 watts of available power. If I plug in a 100 watt bulb I now have only 80 watts of available power until I blow that fuse. Is that correct?

Here is a conversion site that may help out.

BatteryStuff Tools | AC to DC Amperage Calclator Through An Inverter

PineForestCamper · 05-08-2013, 04:17 PM

Ultimate Goals...
1. Looking into the possibility of running items like a popcorn maker (1000w), juicer (1200w) and the LED tv (?) off of the 12v outlet supplied in my camper rather than fire up the generator.

2. As a bonus learn more about 12v and "power" in general as I want to wire up my LED awning lights to 12v and want to tap into existing source w/o overloading it.

Was doing the light bulb equation to put a visual on fuse capacity.

garbonz · 05-08-2013, 04:34 PM

Quote:

Originally Posted by WarMovies

Ultimate Goals...
1. Looking into the possibility of running items like a popcorn maker (1000w), juicer (1200w) and the LED tv (?) off of the 12v outlet supplied in my camper rather than fire up the generator.

2. As a bonus learn more about 12v and "power" in general as I want to wire up my LED awning lights to 12v and want to tap into existing source w/o overloading it.

Was doing the light bulb equation to put a visual on fuse capacity.

That 12v outlet was probably designed for a small 12 volt TV. NOT much else.

Best idea once you are up above a couple hundred watts is to put an inverter close to the battery bank with correct gauge wire ( get at least a couple hundred amp hours of battery or more) and then run a 110 volt wire to an outlet box where you want it to run your appliances.

Pooneil · 05-08-2013, 04:36 PM

Quote:

Originally Posted by WarMovies

Ultimate Goals...
1. Looking into the possibility of running items like a popcorn maker (1000w), juicer (1200w) and the LED tv (?) off of the 12v outlet supplied in my camper rather than fire up the generator.
.

Just forget about those kinds of loads. The tongue weight for that battery setup for that would crush your TV's rear axle. Make Jiffy Pop on the fire and eat the fruit or bring your juice from home. You are camping, scale your activities accordingly.

You need to first understand the capacity of your battery to deliver electricity. Find the reserve capacity of your battery. It is usually the number of minutes that 25 amps (300 watts) can be drawn until the battery is dead. Since you don't want to kill the battery, figure you have about half of that time as usable capacity. A typical group 24 battery that dealers supply may have a RC of 140 minutes making just over an hour of useable draw at 300 watts. It not even be able to deliver 1000 watts without damage. That kind of draw is for cranking batteries. Deep cycles simply are not made for it.

**wmtire** · 05-08-2013, 04:37 PM

Quote:

Originally Posted by WarMovies

Ultimate Goals...
1. Looking into the possibility of running items like a popcorn maker (1000w), juicer (1200w) and the LED tv (?) off of the 12v outlet supplied in my camper rather than fire up the generator.

2. As a bonus learn more about 12v and "power" in general as I want to wire up my LED awning lights to 12v and want to tap into existing source w/o overloading it.

Was doing the light bulb equation to put a visual on fuse capacity.

Okay, let's see if we can make this simpler in the conversions. I'm going to round off stuff to make it easier and not take into account that 12 volt can be really 12.5 volt.....or AC voltage drops requiring more amps, inverter inefficiences, etc.

Let's do this two ways: First let's figure wattage which is volts times amps.

120 volts AC times 10 amps equal 1200 watts....or what your juicer needs to run off of AC/electricity. You would need 10 amps of AC to power this juicer, and on a 30 amp equipped RV, this is a full third of your available amps that you have.

You can do the the math another way and get amps. Let's take watts and divide by voltage (either 120 volt AC or 12 volt DC). This time we will take the known 1200 watts of the juicer but divide it by the 12 volts.....which would be 100 amps DC.

So to run a 1200 watt juicer, you would need to use 100 amps of DC (battery), and would need greater than a 100 amp DC fuse and properly sized wire for this.

EDIT: If you plug the above numbers (120 volt AC and 10 amps) to get 1200 watts in the conversion link, it states you need 110.4 amps DC to run the juicer.

----------------------------------------------
To put it even simpler, let's talk about your converter. Your RV converter is what converts AC power into DC power. Your converter is usually rated for something like 45, 55, or 75 DC amps. Say your converter can supply 75 amps of DC power to provide power for your furnace, fridge, detectors, battery charger, and so forth.

Your 1200 watt juicer that will require 100+ amps of DC, would be using more DC power than everything else combined in your trailer that your converter powers at 75 amps DC........and would also be need to be on it's own circuit and couldn't be run thru the converter at all since it would require more amps than the entire total of the converter is capable of producing..

Does that help any in the understanding of the draws?

If I misquoted or made any errors in my posts, would someone please clarify?

PineForestCamper · 05-08-2013, 05:02 PM

Quote:

Originally Posted by wmtire

You 1200 watt juicer that will require 100+ amps of DC, would be using more DC power than everything else combined in your trailer that your converter powers at 75 amps DC.

Does that help any in the understanding of the draws?

When I get home I'm going to give my generator a big kiss. We are going to become good friends this summer.

So is it safe to say that DC (12v) power is really best used to power items that draw relatively little amounts of power compared to items that run off of AC? Items like my LED awning lights and not a popcorn maker or juicer.

TURBS · 05-08-2013, 05:04 PM

When ever you plan to use an inverter, you'll need a big battery bank to make it even worth while !

Pooneil · 05-08-2013, 05:06 PM

Quote:

Originally Posted by WarMovies

When I get home I'm going to give my generator a big kiss. We are going to become good friends this summer.

So is it safe to say that DC (12v) power is really best used to power items that draw relatively little amounts of power compared to items that run off of AC? Items like my LED awning lights and not a popcorn maker or juicer.

Sounds like you are on the right track. If you want big power, bring big power.

**wmtire** · 05-08-2013, 05:16 PM

Quote:

Originally Posted by WarMovies

So is it safe to say that DC (12v) power is really best used to power items that draw relatively little amounts of power compared to items that run off of AC? Items like my LED awning lights and not a popcorn maker or juicer.

Not only safe, but accurate. That's why your RV is powered the way it is. You also should fully understand why your air-conditioner, microwave, and electric water heater element are AC only items..........due to their large energy requirements.

Now that you hopefully understand it all better, you can tell that generator to "pucker up, buttercup".

garbonz · 05-08-2013, 05:45 PM

Quote:

Originally Posted by WarMovies

When I get home I'm going to give my generator a big kiss. We are going to become good friends this summer.

So is it safe to say that DC (12v) power is really best used to power items that draw relatively little amounts of power compared to items that run off of AC? Items like my LED awning lights and not a popcorn maker or juicer.

Yes that's exactly it. Especially if you have a generator and plan to use it.

PineForestCamper · 05-08-2013, 10:22 PM

I have a couple of take aways from all of this.

First of all thanks to everyone who posted. I did not address all of you but I read and reread every post. This is a great place to learn. No doubt about it.

Secondly, DC power with deep cycle batteries is best used to power items that are specifically made to operate on DC power. There are inverters available to convert power to run AC devices such as my juicer/popcorn maker but its not advisable. I have a 2000w Champion generator so fire that thing up whenever I am going to use high wattage items. They will only be running for a few minutes at a time anyways.

I now need to figure out how and where I am going to wire up the LED awning lights into DC power by tapping into existing power.

Broadway Joe · 05-08-2013, 11:10 PM

I tapped into one of the lights in my lower cargo bay. The leds only draw 1 - 2 amps.

**wmtire** · 05-09-2013, 03:26 AM

Quote:

Originally Posted by WarMovies

Secondly, DC power with deep cycle batteries is best used to power items that are specifically made to operate on DC power. There are inverters available to convert power to run AC devices such as my juicer/popcorn maker but its not advisable. I have a 2000w Champion generator so fire that thing up whenever I am going to use high wattage items. They will only be running for a few minutes at a time anyways.

WarMovies, it definitely sounds like you got the knowledge of how it all works now.....and hopefully others who may read this forum in the future will understand it too.

As been stated, you will need a large battery bank to run inverters that will output the necessary AC power you may need. These inverters come in different sizes, and the more they output, the more battery capacity you need. The size and weights of having several batteries(bank) are definitely a limiting factor. You usually only see large inverters in larger motorhomes, etc......although they can certainly be installed in trailers if needed per application.

Here is a fairly good article that you may find interesting, and you probably will understand it all now. It also has recommendations on wire sizes, etc. I just scanned over the article and didn't verify the sizes, but it's probably correct.

http://www.magnumenergy.com/Literatu...lent_power.pdf

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