Run LED lights direct from 12v or inverter.

Stone Mason
Stone Mason Registered Users Posts: 16
Just trying to solve an argument.

System
500w pv 12v
1000w inverter 240v
Outback controller

If you have a small off grid home and want to run LED lighting would it be better to run lighting directly off 12v or run lighting off inverter with 12v transformers for the lighting.

Argument is more losses from voltage drop on direct 12v or inverter and transformers?
:confused:

Factoring in there is a lot of time when only lighting will be used... cooking dinner etc.
Thanks

Comments

  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Run LED lights direct from 12v or inverter.

    How many lights will usually be on at one time? And what wattage?
    For instance, if only running 3 or 4 one watt LED's off a 1000 watt inverter, the inverter alone could be consuming 20 watts just sitting there idling, providing power just in case you might turn on a light. And when running the lights, will add it's running load to that of the lights. If you want to run the lights off AC, I definitely would use a far smaller, less energy hungry inverter - - - that is unless you're lighting up the Wal*Mart parking lot :p
    Better still, eliminate the drain of running an inverter altogether if you have only a few small wattage lights, get 12 volt LED lights, then the only drain would be when a light is actually on, and then only the wattage of the light. Using a step-down transformer from 220 VAC to whatever voltage you want for the lights would work too, and if the transformer is small, would add little extra load to the batteries compared to the 1000 watt inverter powering it. Unless you have power to spare, have extremely long runs from battery to lights that require high voltage to cut transmission losses, or have huge lights, go with 12 volt lights, only use them at night when the voltage isn't so high (charging batteries) and keep that 1000 watt inverter shut down unless it's really needed for big loads. Unless of course you have power to spare, which most of us don't.
    I have a Morningstar TS-300 running 24/7 anyway for certain items that need it, so run my LED lights off that (it's on anyway) and don't have to worry about voltage surges from battery EQ etc driving the LEDs too hard and shortening their life.
  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    Re: Run LED lights direct from 12v or inverter.

    I use these.

    Powered by the Load terminal of my charge controller, I placed my DMM in series with the 12V, 4W LED. When engaged, it measures 280 mA, or 3.4 Watts. It really does replace a 20 Watt MR16. The only bummer is the cost, but it's bright, compact, and low-power. I use 3 of them, mounted in a recycled track-light, and controlled by a standard light switch(To the moderators who will say this is a bad idea, this circuit has a 1A fast blow Fuse in-between SunSaver and switch. Polarity must be observed). If I should happen to leave the lights on, the SunSaver's LVD will disconnect at 11 volts.

    Just trying to solve an argument.

    System
    500w pv 12v
    1000w inverter 240v
    Outback controller

    If you have a small off grid home and want to run LED lighting would it be better to run lighting directly off 12v or run lighting off inverter with 12v transformers for the lighting.

    Argument is more losses from voltage drop on direct 12v or inverter and transformers?
    :confused:

    Factoring in there is a lot of time when only lighting will be used... cooking dinner etc.
    Thanks
  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    Re: Run LED lights direct from 12v or inverter.

    My outside lights & window candles are all run directly from the 12 volts.

    Unless they are in a cluster far from the battery, go KISS and do direct w/o inverter.

    For wire, my candles are on 18 AWG and the outside are on 10 AWG.
  • bsolar
    bsolar Solar Expert Posts: 103 ✭✭✭
    Re: Run LED lights direct from 12v or inverter.

    well a transformer will always be some dead weight and a draw, and the inverter will always pull some, although in the end if all your running is a couple of low watt led's its not going to be an issue on anything but the smallest system i would imagine ..

    the resistance from the wire in a 12v application would be a non-issue because its not adding to the draw but actually reducing the power consumption, and unless one needs to extract maximum performance and light from a led that would be the ideal situation is run them off 12v with nothing inbetween ..

    ..ive experimented with a couple of higher power led's in the 10-20w range and here is the info i can convey: typically a 20w screw in florescent will produce more light than the 20w led's (i have anyway) at max power so imo the florescents would be more efficient if one needs maximum light per watt used, however, if running a 12v led lighting setup right off the bank its real easy to fine tune the wattage and draw you want with a simple 2$ dimmer
    http://cgi.ebay.com/LED-Bulb-Dimmer-Adjustable-Brightness-Controller-DC-12V-/230638577490?pt=LH_DefaultDomain_0&hash=item35b3216752

    again though, wire size is a non-issue imo up to a point .. you wouldnt want to run a string of (10) 12v-20w LED's on a 22 gauge wire simply because you might melt it and set something on fire ..
  • System2
    System2 Posts: 6,290 admin
    Re: Run LED lights direct from 12v or inverter.

    A couple of weeks ago, I purchased 4 LED spotlights to replace the lights in my kitchen. Bought these at Home Led Light Accessories LED Controllers LED Power Supplies Depot, about $28 each. Unlike many LED lights I've looked at, these weren't the very white, almost blue lights. These are a very warm color.
  • oil pan 4
    oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    Re: Run LED lights direct from 12v or inverter.

    At no more than an amp, running the LEDs off DC and 18 gauge wire will be fine.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Run LED lights direct from 12v or inverter.

    the issue I ran into was having to modify a 'transformer type' track lighting fixture to allow using 12v . solution was to remove the transformer, or use GU10 fixtures and swap out the gu10 pin holder for an MR16 holder. Otherwise it is simple, wire as though it will be 'regular' power (10 AWG wire?) and substitute 12v and appropriate 12v lights. I used MR16's also and there are lots of eBay suppliers to get you a bunch of cheap ones to start, then when you find the frequency (degrees Kalvin) you like buy a bunch.

    HTH
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • MasterJimmy
    MasterJimmy Registered Users Posts: 2
    Re: Run LED lights direct from 12v or inverter.

    Hello. i dont mean to hijack the thread but i am trying top build a tron identity dosc replica for a costume. i found this thread during a google search trying to find out how to do what i have in mind.

    for now im just going to go with building a few parallel circuits and running them on a 12v battery (really tiny one you find at radio shack) i have a 12v inverter ( radio shack 2760341) that outputs 160VAC max at 1W max. i got it for an LED strip that was not nearly bright enough. what i want to do is to wire in the inverter (which i have already successfully {and tested} spliced the battery holder into so it can either run a device on battery or from a wall wart) so i can either run around at a convention with the disc on battery, or when at home i can plug it in and put it on the display stand im building as a lamp or night light for my kid.

    how can i do this? worst case i just wire in a receptacle for a 12V wall wart, which i know is a hell of a lot easier. its just that i am trying to learn everything i can so doing the project this way is a good challenge.

    i had absolutely no experience designing circuits before i did this and did well. all i ask is give me good plain english explanantions or a source for the info i need such as the following site which helps me greatly doing what i have done so far

    http://www.evilmadscientist.com/2012/resistors-for-leds/
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Run LED lights direct from 12v or inverter.

    Welcome to the forum... That inverter you are looking at with the Radio Shack device is a really a high voltage AC supply for Electroluminescent material.

    http://en.wikipedia.org/wiki/Electroluminescent_wire
    http://en.wikipedia.org/wiki/Electroluminescence

    It will not really work well with LEDs (in general).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MasterJimmy
    MasterJimmy Registered Users Posts: 2
    Re: Run LED lights direct from 12v or inverter.

    It will not really work well with LEDs (in general).

    You cruel sadistic tyrant! crushing the hopes and dreams of a neophyte electrogeek. i **** in your general direction! seriously though: "crap. well it was a cool idea anyway. mostly i just didnt want to waste the parts. the LED strip is rated for 1000 hours which to me is a joke.

    so i guess i just go with cannibalizing the connector into the disc build and finding a 12V wall wart. thank you for the help though.im pretty sure of how it will work but just wanted to get a second opinion first, a wall wart outputs in DC if i remember correctly?

    so if that's the case my idea will work. just wanted to check if there would be any issues. i do have several projects planned for taking my house off the grid i will post on later and this forum seems tio be a great site to get ideas and advice.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Run LED lights direct from 12v or inverter.

    A wall wart is (usually) an AC Transformer and may, or may not, have a DC rectifier, a few filter capacitors, etc... You can get a good start by reading the markings on the unit.

    There are so many different ways to "derive" power these days (electronics are cheap, engineering/labor is cheap, and copper is expensive)--It is getting very difficult to make any assumptions without taking things apart and/or understanding the labels and how to use a meter/oscilloscope.

    LEDs are quite different when compared with Filament Bulbs and EL panels/wires...

    LEDs are Light Emitting Diodes--And when you want one to light up, you supply a DC voltage (proper polarity) across the diode junction (between a volt or two, to 5-6 volts or so for the very bright White LEDs). But, if you study diodes, the have have an current/voltage curve that is not linear... If you supply just a bit more voltage, the current goes way up (diode will overheat and die at some point).

    So, what you need is a "ballast"--This is a device to limit current flow through the Diode. In the simplest form, you use a resistor to limit the current through the LED... To a full analog or switching power supply that outputs a fixed current (vs a fixed voltage--like a battery).

    We can help with basic electric theory here--You need to know some--Basically enough to work on a boat/car's electrical system and do some basic house wiring. We really are not setup here to help with electricity 101 through electronics 800.

    If you have specific questions, we can usually handle those.

    Take care,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: Run LED lights direct from 12v or inverter.
    so i guess i just go with cannibalizing the connector into the disc build and finding a 12V wall wart. thank you for the help though.im pretty sure of how it will work but just wanted to get a second opinion first, a wall wart outputs in DC if i remember correctly?

    They're different voltages. An important think is to look at the power rating. Most of them provide very small power. It should be enough for your LED.