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Old 09-08-06, 09:02 AM   #1
explody pup
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Question for the electrically inclinded - portable power

So for reasons that will remain unspecified, I need to be able to power a 100 foot strand of christmas lights and for it to be completely portable.

I was thinking maybe a 6-volt lantern battery. But I have no idea how long that would power the christmas lights or how I'd hook the lights up to the battery.

Thats where you geniuses and your sweet, juicy brains come in. How can I make this happen? Portability (and cost) is key, so I dunno if I'd be able to do a power inverter. Think about the size of a hip pack, for reference.

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Old 09-08-06, 09:05 AM   #2
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Dinky 12v motorcycle battery and a cheapo converter (wimpy ones aren't that pricey.) 100 feet of tiny lights isn't gonna take much juice.

I'm dying to hear you specify the reason.
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Old 09-08-06, 09:06 AM   #3
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That said, if you knew the wiring scheme and wattage for the strand if lights you're going to use, you might be able to power it without the inverter. 12vdc will light bulbs, of course.
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Old 09-08-06, 09:31 AM   #4
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Quote:
Originally Posted by SaabFan
Dinky 12v motorcycle battery and a cheapo converter (wimpy ones aren't that pricey.) 100 feet of tiny lights isn't gonna take much juice.

I'm dying to hear you specify the reason.
How big are these batteries and what kind of converter should I look for?
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Old 09-08-06, 09:38 AM   #5
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A motorcycle battery is probably roughly the size of two 6v lantern batteries.

Seriously though, I'd ditch the converter and go with connecting the lights right to the battery. Pick a motorcycle battery or lantern battery depending on how much runtime you want. Depending on how the lights are wired and what resistance (wattage) the bulbs are, it'll either pop em all or work out nicely.
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Old 09-08-06, 09:47 AM   #6
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Quote:
Originally Posted by SaabFan
A motorcycle battery is probably roughly the size of two 6v lantern batteries.

Seriously though, I'd ditch the converter and go with connecting the lights right to the battery. Pick a motorcycle battery or lantern battery depending on how much runtime you want. Depending on how the lights are wired and what resistance (wattage) the bulbs are, it'll either pop em all or work out nicely.
I just need it to last 4-5 hours. I'm guessing the lantern battery will do the trick. I'll have to check the wattage on the lights, though most I've check out online are ~5 volts.
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Old 09-08-06, 10:06 AM   #7
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SaabFan has the right answer.
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Old 09-08-06, 10:08 AM   #8
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20Ah 12V gel cell (emergency starter unit from a box-mart or auto store) ... cheap, comes w/recharger, etc. ... you can use an inverter if the draw isn't too high on the string of lights...
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Old 09-08-06, 10:26 AM   #9
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I doubt that DC from a 6 or 12 volt battery is going to work directly. You have to consider the voltage drop of 200 feet (100 feet to the end and back) of 18 or maybe 16 guage wire + the bulbs. Thats a lot of voltage drop. I would connect a small inverter, the type that plugs in a lighter outlet, to a battery so you're running the lights on 110v.

SB
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Old 09-08-06, 10:37 AM   #10
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Quote:
Originally Posted by SoonerBent
I doubt that DC from a 6 or 12 volt battery is going to work directly. You have to consider the voltage drop of 200 feet (100 feet to the end and back) of 18 or maybe 16 guage wire + the bulbs. Thats a lot of voltage drop. I would connect a small inverter, the type that plugs in a lighter outlet, to a battery so you're running the lights on 110v.

SB



A little 50W inverter or less would do the trick!
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Old 09-08-06, 10:51 AM   #11
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Hmmmmm... this is looking to get more expensive than I thought. I'd be better off spending this money on beer.
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Old 09-08-06, 03:43 PM   #12
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A 12v car battery should do it.
Figure out the current draw each bulb requires, add them up. Your battery will have an Ampere HOur rating to help you determine how long it will power the bulbs for.
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Old 09-08-06, 05:31 PM   #13
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Do you have an ohm meter? With the ohms of the complete string and that of a single bulb and the total number of bulbs I could tell you all of what you need.
At least give me the bulb count and is the plug just a plain little plug or is it a transformer(heavy cube)?

Or 19 6-volt batteries connected in series would give you 114 volts, OR 9 12-volt lead acid motorcycle batts, OR 12 9-volt jobs


If the bulbs in the string are in series(Pull one out, do the rest go out? If yes, it's in series.) which is likely, you can tap into the string in the middle and use only 60 volts(1/2), cut those in half again for 30v(1/4) or use 1/3 for 40v
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Old 09-08-06, 05:45 PM   #14
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1) First off, what is the wiring-schematic on the Christmas lights? They typically use several parallel-series circuits to divide the 120v wall-voltage down to provide each bulb with just the right current. So the only way you're gonna drive off-the-shelf lights is with 120v, so a 12v battery and inverter is needed. Easiest solution as far as time and effort goes. Also costliest as well.

2) Now, you can also use a gel-cell/motorcycle battery straight-up with 12v bulbs. But you'll have to wire them up yourself, all in parallel with a single wire. Nice thing about this arrangement is that if a single bulb fails, it doesn't take out several others or the entire line with it... Most elegant and simple solution, but will take a lot of time.

Last edited by DannoXYZ; 09-08-06 at 07:44 PM.
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Old 09-08-06, 06:04 PM   #15
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http://michaelbluejay.com/electricit...as-lights.html
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Old 09-08-06, 06:23 PM   #16
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If it's a one time deal, and you've got a professional photography store with a rental department near by. See what they'd charge to rent a portable power block. Hensel, Dynalite, lotsa others make kits that would power those lights 8-10 hours easy and are made for complete portability.
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Old 09-08-06, 07:34 PM   #17
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$8.67 LED lights

Additional Information:
Color is Blue & Clear
Number of Bulbs: 150
15 ft.
Drop is 21 in.
30 Drops at 7, 4, 6 and 3 in.
Spacing Between Drops is 6 in.
White Wire
2.5 Volts
170mA
Connect Up to 3 Sets
Comes with Gutter Clips Included
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Old 09-08-06, 07:46 PM   #18
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Here's a cheap 150-watt inverter. You'll need a gel-cell or motorcycle-battery as you'll be sucking about 10-amps. Should be able to drive a string of 120v Christmas lights easily...
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Old 09-08-06, 08:08 PM   #19
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An electronic hobbist magazine "Nuts and Volts" has an ad in their free sample electronic issue for really cheap sets of low voltage, mutli-colored, flashing patterns LED Christmas lights. Just dig for the ad. Should run for hours off of a 12 volts (2-3 lb) battery.
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