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LED Christmas lights for backup
I guess there are now LED Christmas lights for outdoor displays.
Questions.. Wind the strand up into a ball and tape up into a lamp/reflector? These LEDs are 12vdc with a 120v capacitor/reducer? Could you hookup a 12v car battery to a cluster of these lights? Thanks for any input and enjoy your Sunday afernoon I'm up to the garden to mulch the winter carrot bed. |
Re: LED Christmas lights for backup
No response...Ah well, sometimes my brainstorms turn into just braindrizzles! HA!
Might just pick up a few LED strands in after Christmas sales and see what I can do with them. Good luck |
Re: LED Christmas lights for backup
I dunno about the battery. We just got some LED outdoor lights and put em up last night. They are suprisingly bright for mini LED's. Your idea isnt half bad at all, imo.
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Re: LED Christmas lights for backup
LEDs are diodes, which means that they are current-sensitive devices, not voltage. If you just hook up 12 VDC to them, you'll cook 'em; you need a ballast resistor, because the resistance of an operating LED is very low (like, single-digit ohms).
You'd need to measure how much current the entire string of lights draws, and then slap a resistor into the circuit such that the appropriate current is delivered at 12 V with the bulk of the voltage drop being across that resistor. |
Re: LED Christmas lights for backup
Thanks AGbar, I've a friend with the proper testing gear...
The resistor...OTS @ Radioshack or do you have a good online source? My level of electronic knowledge amounts to correctly putting batteries into a flashlight..HA! |
Re: LED Christmas lights for backup
Quote:
OTS will be fine (if radio shack still carries the part!) Only concern is to make sure the resistor can handle the power you're trying to run through it: don't put a watt through a 1/4 watt resistor! But on the other hand, if you only need 1 watt and get yourself a 10 watt resistor, you'll be just fine. I = V/R P = IV = (I^2)*R P = power (watts) I = current (amps) V = voltage (volts) (AKA "tension" in the UK) R = resistance (ohms) EDIT: if RadioShack doesn't have what you need, try someplace like www.DigiKey.com. Remember, though, that resistors are very, very cheap; you might need to order a dozen or so before they ship, and you'll still pay more in shipping than for the parts. Still, it'll only be a few bucks all told at the worst. EDIT AGAIN: And the current you want to measure is on the 12 V side of the lights. You don't care about how much current is coming out of the wall at 120 VAC. You want to know how much is running through the lights at 12 VDC. (just to be clear) |
Re: LED Christmas lights for backup
Or you could just go to harbor freight tools and buy 2 led flashlights for 4 bucks.
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Re: LED Christmas lights for backup
http://michaelbluejay.com/batteries/...as-lights.html
<table border="0" cellpadding="4"><tbody><tr><td style="font-family: Verdana; font-style: normal; font-variant: normal; font-weight: normal; font-size: 11px; line-height: 140%; font-size-adjust: none; font-stretch: normal;">Most Christmas lights have to be plugged into the wall to get power. But if you could run them off batteries you could put them anywhere an outlet isn't available -- such as on a bicycle. The kind of electricity you get from the wall is called AC, and the kind you get from batteries is called DC. You have three options for running Christmas lights off DC (batteries):
When I first wrote this page some years ago, LED Xmas lights were rare, and there certainly weren't any wired to run off batteries, so I was sharing two big secrets: one, that you want LED's for the longer battery life, and two, how to rewire them to run off batteries. But now you can buy an off-the-shelf solution without having to rewire anything, as listed in the yellow box on the left: lights, battery, and charger. The only thing extra I added was some connectors on the ends of the wires to allow me to easily "plug" the battery to the lights or to the charger. This is a 2200mAh battery and I get 31 hours of runtime (!) with this combo. So those three off-the-shelf products are the easiest solution. There are others, though. Here are all your options:
How much runtime you'll get from your batteries Calculating electrical use is easy. The formula is very simple: Usually we'll abbreviate. (e.g., 2.5V = 2.5 volts, 25W = 25 watts).Volts x Amps = Watts You don't even have to know what volts, amps, or watts are, as long as you know the formula. When you use a watt of electricity for an hour, that's a watt-hour, or Wh. An amp of electricity for an hour is an amp-hour, or Ah. Batteries store such a tiny amount of electricity that they're usually rated in milliamp-hours instead of amp-hours (mAh). 1800mAh is the same as 1.8Ah. A typical 50-bulb strand of (NON-LED) Christmas lights uses 25 watts. So each bulb uses about half a watt. (Remember that, we'll use it later.) Now we need to see how much electricity is stored in a battery. A typical rechargeable AA battery (NiMH) puts out 1.2V and is rated at 2200mAh. Remembering that V x A = W, we see that a single battery has a capacity of 1.2V x 2.2Ah = 2.64Wh. But the lights use 25 watts. So you'd need ten batteries to power your lights for just one hour. Ouch. You have four options for getting more runtime out of your batteries:
Now that we know that we need to either use LED's, few lights, or lots of battery power, let's pick a power source for our lights. Choosing batteries You can use standard household batteries (AA, AAA, etc.), or you can buy a battery pack, like the one listed on the top of this page. The advantage of a big battery pack is that there's only one thing to charge. A single 12V pack takes the place of ten individual household batteries. It's a lot easier to charge the one pack than ten separate batteries. On the other hand, if your lightset requires only 2 or 4 batteries, then it's cheaper to just use those batteries than to buy a big pack. Each rechargeable battery (AA, AAA, etc.) puts out 1.2V. If you need 6.0V, then that's five batteries (5 x 1.2V = 6.0V). NON-rechargeable batteries put out more voltage (1.5V), but I don't recommend them because it's wasteful to use disposable batteries. It's certainly possible to do, but if you choose to do so then you're on your own. The numbers that follow assume you're using rechargeables. To wire up batteries to your lightset, you just need a battery holder from Radio Shack, which costs like $1 or something. If you need an odd number of batteries, like 5, then get a 4-battery holder and a 1-battery holder and tie the wires together. Connect opposite colors together (red +black). The number of batteries you'll use depends on how much voltage you need:
Rewiring Christmas lights to run off batteries Here's where you get to play mad scientist. Many devices run off only AC or DC, but lights aren't picky and will run off either. The trick is just to rewire the strand so the bulbs get the proper voltage. Remember, you really really really should use LED lights or the batteries just won't last very long. Even so, we'll use standard (non-LED) bulbs in our example below because they're the most common. A wall outlet supplies about 120V, so if there are 50 lights in the strand, each bulb gets 2.4V. The bulbs actually want 2.5V, so supplying them only 2.4V makes them just a tiny bit dimmer, but not much, and the reduced voltage makes them last longer anyway. In our example below we'll supply 9.6V to our strand with batteries, which will power four bulbs (4 x 2.5V = 10V). Before you start screaming that four bulbs isn't enough, don't worry, in a minute I'll show you how to wire several sets of four together. Most Xmas bulbs are 2.5V but some are different, and they could be more or less. Usually the voltage is printed on the box the lights came in or on a label on the strand. If they're LED lights then every color has a different voltage; white LED's are generally ~3.5V. If you can't find the voltage, check with the manufacturer. Also, don't assume that if a 50-bulb strand has 2.5V bulbs that a 100-bulb strand must have 1.25V bulbs; it's more likely that the 100-bulb strand is just two 50-bulb strands wired together. Anyway, here's how to wire four 2.5V lights together: <center>http://michaelbluejay.com/batteries/images/xmas1.gif</center> But what if you want to power more than four measley lights? Easy, just create several sets of four lights and hook them all together. You can have as many sets of four as you like, though the more lights you have the quicker the batteries will run out. Here's how to wire three sets of four bulbs together. <center>http://michaelbluejay.com/batteries/images/xmas2.gif</center> Here's what it looks like with actual lights: </td> <td valign="top" width="170"> <center><script language="JavaScript" type="text/javascript"><!-- google_ad_client = "pub-7948311637472652"; google_ad_width = 160; google_ad_height = 600; google_ad_format = "160x600_as"; google_ad_channel ="4620551521"; //--></script> <script language="JavaScript" type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"></script><script src="http://pagead2.googlesyndication.com/pagead/expansion_embed.js"></script><script src="http://googleads.g.doubleclick.net/pagead/test_domain.js"></script><script>google_protectAndRun("ads_core.goog le_render_ad", google_handleError, google_render_ad);</script><ins style="border: medium none ; margin: 0pt; padding: 0pt; display: inline-table; height: 600px; position: relative; visibility: visible; width: 160px;"><ins style="border: medium none ; margin: 0pt; padding: 0pt; display: block; height: 600px; position: relative; visibility: visible; width: 160px;"><iframe allowtransparency="true" hspace="0" id="google_ads_frame1" marginheight="0" marginwidth="0" name="google_ads_frame" src="http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-7948311637472652&format=160x600_as&output=html&h=6 00&w=160&lmt=1260211781&channel=4620551521&flash=1 0.0.32&url=http%3A%2F%2Fmichaelbluejay.com%2Fbatte ries%2Fdc-christmas-lights.html&dt=1260211782071&correlator=1260211782 075&frm=0&ga_vid=2020881856.1260211782&ga_sid=1260 211782&ga_hid=1742798718&ga_fc=0&u_tz=-360&u_his=2&u_java=1&u_h=1050&u_w=1680&u_ah=1020&u _aw=1680&u_cd=32&u_nplug=17&u_nmime=93&biw=1663&bi h=867&ref=http%3A%2F%2Fwww.google.com%2Fsearch%3Fq %3D12volt%2Bled%2Bchristmas%2Blights%26ie%3Dutf-8%26oe%3Dutf-8%26aq%3Dt%26rls%3Dorg.mozilla%3Aen-US%3Aofficial%26client%3Dfirefox-a&fu=0&ifi=1&dtd=81&xpc=CfhlGC9VuV&p=http%3A//michaelbluejay.com" style="left: 0pt; position: absolute; top: 0pt;" vspace="0" frameborder="0" height="600" scrolling="no" width="160"></iframe></ins></ins> <table bgcolor="#000066" border="0" cellpadding="4" cellspacing="1" height="240" width="120"> <tbody><tr bgcolor="#ffffff"> <td style="font-family: Arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 12px; line-height: normal; font-size-adjust: none; font-stretch: normal;" onmouseover="this.style.backgroundColor='yellow'" onmouseout="this.style.backgroundColor='white'" onclick="window.location='http://airfare.michaelbluejay.com/'" valign="top"> <center>http://michaelbluejay.com/promo/plane.gif How to find the Cheapest Airfare Everything you wanna know. 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Might save your life. (Visit now...) </center> </td> </tr> </tbody></table> </center> </td> </tr> </tbody></table> <table border="0"> <tbody><tr> <td> STEP 1: Make three sets of four bulbs eachI tied up the slack so the lights would be more compact. There's nothing special between each bulb, just a continuous wire. http://michaelbluejay.com/batteries/images/xmas-a.jpg STEP 2: Connect all the "heads" together. That is, make sure the beginning of each set is connected by a wire. Normally you'd wrap the power wire around the other wires, but I made the wire separate here so it's easier to see how the wiring works. http://michaelbluejay.com/batteries/images/xmas-b.jpg STEP 3: Connect all the "tails" together. That is, make sure the end of each set is connected by a wire. Normally the return wire is also wrapped around the other wires. I made it separate so it's easy to see how it's wired. Note the battery pack is actually eight batteries even though only four are visible (the other four are on the bottom; it's two batteries deep). http://michaelbluejay.com/batteries/images/xmas-c.jpg <table style="font-family: Arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 13px; line-height: 17px; font-size-adjust: none; font-stretch: normal;" border="0" width="600"> <tbody><tr> <td height="1"> This set would last almost two hours on a set of eight AA 1.2V NiMH batteries with 1800mAH capacity each (like the kind Radio Shack sells). Remember that each bulb uses half a watt-hour per hour. So 12 bulbs use 6wH per hour. Our batteries store (8 batteries x 1.2V x 1800mAh = ) 17,280mWh, or 17 wH. Therefore our 17 wH battery pack will power this 6-watt strand for almost three hours. So there you have it, three ways to get Christmas lights to run off batteries! You might also like How Christmas Lights Work from HowStuffWorks.com. I'd like to give extra-special thanks to my good friend Jerry Chamkis (inventor of the Kosmophone) for teaching me about electronics so I could know how to do this kind of stuff myself. 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Re: LED Christmas lights for backup
Quote:
PFFT! Where's the fun in that! :biggrin: |
Re: LED Christmas lights for backup
Pull a string of Xmas lights through an equal length of dryer duct. Pile it in the corner. Makes a great mood light. Of course, the mood is like "WTF?"
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Re: LED Christmas lights for backup
Thanks again Agbar and Techguy, That's some good info, I've considered an inverter for this and other projects.
Looks like I'm set for a cheap and SAFE alternate light system (we have plenty of kerosene lamps,wicks,mantles and properly stored kerosene, but there is always that "flame factor"). Have a good week folks. |
Re: LED Christmas lights for backup
QWAK,I have been experimenting with using LED christmas lights as lighting out in the green house bath for about 3 years now. :yes:
Some run on 110 v ac others are battery and have solar chargers. :23_30_104: Generly I would sy they are MOOD LIGHTING -- not very brite but enough so you can get around and not trip over stuff. It is amasing how CHEEP LED have become -- just about 8 or 9 years ago I payed $30.00 for a 2 LED flash light --- this year I bought a 200 LED flash light for $50.00 and it is extreamly brite and runs on 6 AA batteries!:23_30_104: I can see buying some left over LED lights at 75% off after christmas:yes: to play with but for actual USE as emergency back up I think it is worth buying somthing designed to do what you want and need it to do rather than trying to jerry rig somthing! :thinkey: BTW: I bought some 24 led camping lights that look like a flying saucer that run on 4 AA batteries -- I bought 12 $5.00 each and figure I can run them off a 6 volt battery solar charged and use speaker wire to supply each with power with two simple solder joints on each. Voltage drop on a 12' run should be minimal and each to have its own feeder line so all are run in parralel. :thinkey: the DUCK :15_1_70v: |
Re: LED Christmas lights for backup
All -
They are also making some pretty slick LED ropelights these days. In many ways tougher, easier to handle, more weather resistant. Oddly enough, other than Very Large Boats, in which we use mucho yards, Casinos use a ton of them, for the reason that They have this insane half-life of like 100,000 hours. scyth |
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