Electrical configuration questions...

[tinksdad]

I just spent a couple hours searching the previous threads in Electrical Secrets to make sure I know what I'm doing. I think I have a handle on it, but I still have a question or two.

I finally decided to go with a 110/12 V combination for my needs. Found room to put in a raceway like the one in the Generic Benroy plans. The plan is to have shore power inlet, 2 110V outlets (one in the galley and one in the cabin), and a converter for the 12V side (4 or 5 lights and the roof vent fan). No battery for the present, but will make allowances for future install if I ever change my mind. In the mean time for the one and two night trips where shore power is not an option, I will make do with "AA" lighting and accessories.

My questions revolve around the converter. I like the Pyramids that Mike has the links posted for because of the size. They will fit in the raceway very nicely. I couldn't find a pic during my search that showed the inlet hookup. It appears the converters plug into a regular 110 outlet. Am I missing something, or do I have to install a third 110 outlet inside the raceway dedicated to the converter? The Pyramids (and I'm assuming other brands as well) come in models that have different max outputs. For my planned needs, what size output should I consider?

[G-force]

Your 110v will basicaly be a stand alone system that basicaly only works on shore power. Wire up the outlets as you see fit and terminate them in a shore power plug of some sort. The voltage converter can either be hardwired into the 110v system, or I would prefer, just install a dedicated outlet for it wherever you plan on installing it. It probaly needs to be ventalated for heat dissapation so keep that in mind. From there you 12v system will be totaly seperate withthe exception of the hot and ground 12v from the converter. I would run those to a fuse pannel like the Blue Sea one or similar. As for how much power you need, well, you got to do the math. You have to know ahead of time what lights and other 12v items you will be powering, add up all the wattage you need, then you can properly size your wiring and converter. For example if the fan pulls 5 amps (just a wild guess) and you have four 55 watt lights (which is 4.6 amps, divide watts by voltage to get amps) a 10 amp converter would work but be at full load. I would choose a 15 or 20 amp converter to give a safe margin and room to expand in the future. My biggest question, is if you are always going to be on 110 shore power, why bother with 12v lighting? Untill you have a 12v battery system I wouldnt bother. If you want to be proactive, I would put 110v lighting for the majority of the lights, and a few 12v for the future battery install.

Mike

[tinksdad]

The main reason I wanted to go with a dual voltage system is because of the light fixtures I bought for the trailer. I got a slew of these in a package deal off E-bay and they are 12V.


I wanted to keep all brass fixtures and accessories in the trailer and I couldn't find anything small and 110V in brass.

Even if my electrical math is a little rusty, I could calculate what size resistor to wire in line to drop from 110 to 12, but then I still have the difference between AC and DC to contend with. 12V fixtures are DC and 110 is AC. As far as the roof vent is concerned, because of the size of the trailer I could probably get by without a fan in it.

But if I can't make the lights work... I'll keep looking for some small lighting fixtures in 110, and I'm only out $20 (including shipping) for the 12V lights.

[madjack]

...let me add a warning about the Pyramid POWER Supplies...they are not an RV type converter but rather a constant amperage 12vdc power supply...they are excellent for running 12vdc appliances and lights but they will fry the battery if left hooked up continuously...a RV style converter such as the WFCO has a 3 stage charger to charge and protect your batteries as well as space for 120VAC breakers and 12VDC fuses...be wary of the Pyramid!!!!!
madjack

[wlooper89]

I have recently completed the electrical for my teardrop. There are some photos of the electrical installation in my album. I used a 25 amp converter made in China by the World Friendship Company. It is three stage, good for battery charging, contains a cooling fan that runs only when needed and is made specifically for an RV. The cost was just over $100.

As you have, I opted for the 120V AC and 12V DC system. My trailer has a platform in front, so I installed the converter and other electrical things in a box there.

In the beginning I wanted to have an inverter to run 120V things from the battery, but I quickly learned from this group that the amp draw from the battery is higher by a factor of 10 so even a large battery will not last long except for very small 120V items. All of my lights are DC but it is nice to be able to use a microwave oven when 120V shore power is available.

Good luck with your plans.

Bill

[wlooper89]

Me again. I just noticed in the post before mine a mention of WFCO converter. That is what I have and it seems to work fine (World Friendship Company). My 12V reading lights are white but they are also available in brass finish and a couple of styles. The amp draw is less because they are flourescent. There is a photo in my album. Below the base in the photo is a white disk for mounting that is not part of the light fixture. I may change that as the color does not match. The company is called Taylor Made.

Bill

[TPMcGinty]

The main reason I wanted to go with a dual voltage system is because of the light fixtures I bought for the trailer. I got a slew of these in a package deal off E-bay and they are 12V.


I wanted to keep all brass fixtures and accessories in the trailer and I couldn't find anything small and 110V in brass.

Even if my electrical math is a little rusty, I could calculate what size resistor to wire in line to drop from 110 to 12, but then I still have the difference between AC and DC to contend with. 12V fixtures are DC and 110 is AC. As far as the roof vent is concerned, because of the size of the trailer I could probably get by without a fan in it.

But if I can't make the lights work... I'll keep looking for some small lighting fixtures in 110, and I'm only out $20 (including shipping) for the 12V lights.

Nice lights. I got a half dozen off of E-bay too!

[tinksdad]

I knew I came to the right place!! You guys had the answer.... maybe not the one I was looking for; but definitely the one I needed!!

From past experiences, I knew the inverter method was not going to work. It's amazing how quickly a blender mixing a few cocktails through an inverter will drain a battery. I had scrapped that idea from the get-go.

I just needed to reverse my thinking. I'm going to put a battery box on the tongue and get my 12V lighting needs taken care of so I can get up and campable. In the meantime, before I close everything up, I will run my wiring (with some spare circuits just in case) and add the 110 later down the road.

It means I won't be able to use the tongue box I had originally planned because all the components won't fit; but I have another use for that one in mind on a different project. (Some concrete anchors through the bottom, through the flooring and into the slab, along with the padlock adapters, in the back of my walk-in closet in the house and I will have a quite serviceable safe for my handguns and anything else I may feel the need to secure away.)

[wlooper89]

Sounds like a great plan! I certainly do admire everyone who is building the whole trailer, as I bought mine already built except for the electrical system. There is a photo or two in my album of the WFCO converter. It is designed to mount in a rectangular opening about 9" X 6". But I built a small frame for it to sit on the battery box inside my electrical compartment. It is generally not a good idea to put the battery in the same compartment with other electrical gear. To reduce that concern my battery box is vented to the outside, and I have put a vent in the back of the electrical compartment. The battery is a sealed AGM deep cycle type and not supposed to give off gas. When towing the only thing powered is the charge wire from the tow vehicle.

The lights from eBay look nice. Best wishes on your trailer building!

wlooper89