12v LEDs on 120 volt system

hemmjo · January 2015

I started this thread in another place but did not get much response.

I am installing another system, similar to the staff one listed below, in the Dominican Republic for the mission I work with. http://villagemountainmission.org/. This one for the kitchen and property caretaker's small home.

The panels, controls, battery bank and inverter will be in the kitchen, supplying power for lighting there and to the caretakers home about 100 feet away. We are running 10ga wire between the two to supply about 7 amps of 120VAC to the home.

We have some 12v LED area lights, about 2 watts each. They run direct from the batteries where possible. We will have about than 6 in this building. I need a 120vac to 12vdc adapter, I find a lot of them online, but many have poor user ratings.

I don't need much more than 12 watts.

Someone there suggested a wall wart type of supply. I have a few of them from old things, but they are 6-8 watts. I can use multiple adapters, that would require extending the 120 power beyond the planned location to provide power for the lighting. Maybe that is a good idea.

My concern is idle time current draw. Maybe use multiple small worts and turn them off and on instead of using the switch on the LED?

Any other options to consider?

Thanks,

John

706jim · January 2015

Re: 12v LEDs on 120 volt system

I've been through the "run it direct from the battery to save inverter current" logic before. My inverter will tick along at 35ma and runs about 350ma when it senses any load enough to turn itself on. This is about 8 watts using a 24 volt input. Inverter efficiency at this low output is only about 50% and improves to as much as 94% as the load increases to about half of inverter capacity. So, wanting to be the absolutely MOST efficient, I ran a 12 volt supply into my place.

In your case, I think you should use the wall warts simply out of cost and availability and just let the inverter run. How much power will it take overnight just idling?

In my situation, I used to tap 12 volts from a 24 volt battery bank and used this only to charge cell phones.

However, I've since installed a 120VAC to 12 volt DC power supply for these low power loads and it works well. This unit comes from Lee Valley Tools (never cheap there) and is rated at 30 watts. There are others available with outputs of 15 and 60 watts as well.

While I can appreciate that you are using what you have on hand, my recommendation would be to run 120 volts into the auxiliary building and forget about 12 volt stuff as much as possible. Those LED's will work ok, but anything else is subject to tremendous line loss at 12 volts, regardless of wire size.

westbranch · January 2015

Re: 12v LEDs on 120 volt system

I picked this link as it has some good pictures of a GU10 bulb.. GU10 it is similar to an MR16 track light bulb but runs on 110VAC

http://www.gu10.net/ note the locking base

hth

hemmjo · January 2015

Re: 12v LEDs on 120 volt system

Thanks for the input. I have decided to go with 120v led bulbs. I found this bulbs, http://www.amazon.com/gp/product/B00HNIBA0Q/ref=ox_sc_act_title_5?ie=UTF8&psc=1&smid=A3T95V05QKJ0CN. They are cheaper than the 12v LED's brighter 3 watts instead of 2. This will also eliminate the need for a to different wiring systems, 12 VDC and 120 VAC, to the total cost will be lower, which is always good.

John

Alaska Man · January 2015

Re: 12v LEDs on 120 volt system

I use a few of those............. FYI if you have an over the air Antenna for your T.V. viewing SOME LED bulbs will mess with the signal. Not sure why, but I can't have certain bulbs on when using it.

Then again my Antenna is so sensitive that if a truck goes by and steps on the Jake break the signal will also cut out. That usually happens right when Tom Brady throws to Gronkowski in the end zone................. NOOOOOOOOOOOOOOOOOOOOOO!!!

BB. · January 2015

Re: 12v LEDs on 120 volt system

Many electronic ballasts (CFL, LED, etc.) are quite radio frequency "noisy" (cheap to build, not much filtering). Also, CFL are "arc lamps" and LEDs are diodes (which can be electrically noisy too).

Add that digital TV is pretty much 100% OK, or if there is enough noise/weak signal, you get near zero reception.

-Bill

hemmjo · January 2015

Re: 12v LEDs on 120 volt system

So.... you are saying these bulbs may cause RF interference? We have no TV or radio at this location. Our only electronics are cell and a small directional WiFi antenna focused on the cell tower across the valley.

Amazing how complex seemingly simple decisions become!!

Thanks for the input,

John

BB. · January 2015

Re: 12v LEDs on 120 volt system

Yes, they can. Usually moving the bulb away from the receiver/antenna will do it... But even 8 feet may not be enough with some brands/weak reception areas.

-Bill

Alaska Man · January 2015

Re: 12v LEDs on 120 volt system

Yeah, my antenna is on top of the roof about 25' from the lamp in question, but I also have a gain adjustment/signal booster gizmo downstairs to help with reception. We are located right on the edge of the signal. Another 500 yds down the road and no signal. Other LEDs don't interfere at all. I hate to say you will just have to see what works for you at $8 a bulb, but........

Still the 12V LED I was thinking of before we went all 120V were anywhere from $30 - $55 a bulb.

BB. · January 2015

Re: 12v LEDs on 120 volt system

Yea--For CFL and LED, and other expensive bulbs, I always suggest getting one first and try it in your application before you get a bulk pack. The change between manufactures, and sometimes, even from year to year (cost reductions).

-Bill

12v LEDs on 120 volt system

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