I am trying to power some LED strips with batteries.

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DeathAngell

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So here is everything summed up

I am trying to make a Christmas present for someone. They work at a roller skating rink. I want to put a small strip of green LEDs on each of their skates (on the bottom).

I have these lights picked out:
- http://www.getfpv.com/green-led-strip-w-adhesive-back-1m.html
These lights require 12vDC power.

So I found this battery pack:
- https://www.amazon.com/Genssi-Battery-Switch-Holder-Power/dp/B00PMDW7LK
This pack will produce 12v, enough to power the entire LED strip if I use 1.5v batteries. Here is the question:

I would want to cut off 2 small strips of 4LEDs off this strip so there can be ONE STRIP on each skate. How would I power both of these efficiently?
 
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Ironsounds

Ironsounds

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Hello...LED's are very low power and Low voltage devices... what I'm saying is one/two 1.5vdc batteries per skate could work all night... with a different product, it might require a solding iron to do this? B /
Here's some instructions... http://www.instructables.com/id/Intro-to-LED-Strips/

Wiring/cutting them parallel and you need less Voltage to operate them.
Wiring/cutting them series and you need More Voltage to operate them.
 
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DeathAngell

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Yes I am proficient in soldering but on the product page, it says 12v is required to power them. I would want it to last multiple nights off a single set of batteries...
 
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Ironsounds

Ironsounds

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Hello... Yes I'm learning about this too B )... "Up to 12vdc" meaning the max... there is brightness levels with voltage change...

ok... these are called "analog" models with 3 series and 3 parallel electrical paths per LED cell... and +12 Vdc max.

Do you wanna run wires down their legs?

There might be some lower voltage models out there is all I'm saying and maybe put a small 2-battery pack under the skate?


 
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DeathAngell

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Alright. If I am doing this right:
Each LED would require around 7mA to power it.

(400 mA for entire strip, take this number/60) because there are 60 LEDs in the entire strip. This would give me 6.6 repeating. Round this to 7mA.

So now we know it would take 7mA to power each LED.
If I only want to have 12 LEDs, I would take this number and multiply it by 12, which would give me 84 mA total to power all LEDs.

Each AA battery gives out around 1500 mAh, (1.5 A)

Take the 84 and divide it by 1000, end up with .084 amps.

Take the 1500mA and divide it by this number, to get (17,857), so roughly 18 hours of power from a single set of 8 batteries?
 
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Ironsounds

Ironsounds

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Hello... There might be some lower voltage models out there is all I'm saying and maybe put a small 2-battery pack under the skate?

Checking your math now.... But yes like I said they use like nothing... so wiring to a lower voltage packs could work with a different product.... or wired LED cell size.... for example 2x2 led cell would be better for a 9Vdc cell? and we are even more compact and could be mounted under each scate? B /
 
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DeathAngell

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Was my math correct though..?
 
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DeathAngell

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Yes but I would still like them to last as long as I possibly can. Hmm.. a 9v battery under each with a short wire running to the strip of 6 LEDs..?
 
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Ironsounds

Ironsounds

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Hello... Yes... GJ B ) ...that's at full voltage... and brightness... another thing could be added is resistor in series to control your brightness... and that would increase use even longer... that is one reason they are called analog LED's... you can very the voltage to them and make them dim or blink too B )

The digital models have all the kewl effects.
 
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DeathAngell

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Hmm.. how exactly would I fit a resistor into that without it making it look weird..? Also doing the math.. 1 9v battery on each side would provide around 6 hours of battery life. Even though the strip requires 12v for 60 LEDs, I would be using 6 LEDs with a 9v battery.
 
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Ironsounds

Ironsounds

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Hello... the resistors 1/2 watt are supper small too are soldered into the wire path somewhere or on the 9vdc battery case/connector... shirnk tube it... it's done all the time.

You need to get some parts on a bench now... and see what brightness you get with different voltages to the strip... typically they turn off/down lights in the skating rink.
 
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DeathAngell

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So 1/2 watt would be a 100 ohm resistor correct? How much longer would this make the lights last?

Also, if I went for the battery pack idea, what would be the best way to "split" the 12v so both sides could be powered?
 
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DeathAngell

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Yes... I would still need to buy these parts and get them to my house before testing anything. Just trying to figure out about how long the battery would last and stuff.
 
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DeathAngell

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Seems like a lot of work to do all this...

I think I will just keep it simple and go with the 12v battery pack, but how would I split it so a positive and negative lead could go down each leg to the skate?
 
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Ironsounds

Ironsounds

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Hello... http://glowhut.com/3528-led-strip-with-leads-plus-9-v-battery-connector/ $3+
it's already made for you... no solding needed? B ) you can chose your custom length too... and can get the battery and charger added for them at a low cost. Unless you wanna do the DIY route? B /

They have maybe digital controller types too below... with 9Vdc battery connectors. $6+

A remote control too for one model... Kewl stuff for a project like yours and that special person in your life B D
 
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DeathAngell

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So I would need 2 of these, one for each side, 6 inch each. So like $25 total. This site seems kinda shady tbh, would be nice if there was actually demonstrations of it working.

It doesn't say how long they would last but I guess the rechargeable battery would make that not so much of an issue.
 
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Ironsounds

Ironsounds

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Hello... for me it does... it's a easy click and at my door a few days later... B D
https://www.google.com/search?q=3528+SMD&rls=com.microsoft:en-US:IE-SearchBox&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjc3eLexebQAhUCLSYKHTA5CeUQ_AUICSgC&biw=1655&bih=871&dpr=1.16#imgrc=_

You can use that first image and chart on voltage and current characteristics with the color of the LED used... It's not linear for each color, and will change power calulations for the 3528 SMD LED.
 
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