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Can I run different voltage LEDs off a 9V battery? Answered

I have a small project that uses a 3 light LED list that runs off of 3 AAA (4.5V) batteries, but I also want to power a 12V LED string (for cars about 24" long) and I am uncertain the mA draw for either. This is for a follow-up to fine tune my son's 2014 Halloween costume.

I run the 12V string off of 10 LR-44 batteries and get about 3 hours use out of these, so I know the mAh draw is relatively small. I'd like to extend the use of the 24" string. The 3 LED light goes for days on the AAA's. 

Because both lights are used for the same application, I wanted to see if I could join them together in a single power source and power off of 1-9V or 2-9V (in serial for a total of 18V) batteries. I think my preference would be the 18V with an in-line resistor, but I do not know which resistor to use.

Is this the correct approach?

What are other alternatives?

Discussions

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Wired_Mist

4 years ago

It really depends on how much current your light strips are using. Without a doubt I sugest you use a 5v regulator for the lower power LED's. For 12v, I'm not sure about how much heat a resistor would create; I can see it getting toasty ! Try to find a 12v regulator with sufficient amperage at your local electronics store. My favourite is the 5Amp LM1084 only downside, it needs some extra circuitry to function. As per the battery, Personaly, I would use a small 12v sealed battery(Rechargeable, Bonus!). If it needs to be portable and you value lightweight over battery life your 2x 9V idea could work.

You will get a better answer if you could provide the current consumption, or the rating in watts would also help

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HaydnAWired_Mist

Answer 3 years ago

Does anyone have any suggestions about how you would find things like current consumption of an LED array? I too am trying to find out how to power a series of LEDs (in my case it is a series of 24 blinking Pet Collar LEDs (e.g.

http://www.amazon.com/HomeFusion-Collar-Flashing-Flasher-Visibility/dp/B00L59NG3S) but there is no details anywhere about how much current it draws or what resisters are in them or anything. The original poster says specifically; "I am uncertain the mA draw for either". Many products, just don't have that information. So if it is important, how do you find out what it is?

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mpilchfamily

4 years ago

A 9V battery is about the worst power source you can use. They don't hold much power. You would be better off with a battery pack of 6 AAA batteries. You'll need at least a 12V power source to run the LEDs. A voltage regulator may be needed to drop the voltage to a more reasonable level for the 3 LED light.

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icengmpilchfamily

Answer 4 years ago

There are worst batteries in the amount of Power, but notin convenienceandsize ! .....Plus you can get a 9 volt Lithium at half the weight, 5 X the Power and unfortunately nine times the cost.

I get over Four hours from 9V driving that six dollar 12volt 15 blue LED strip in my ible and it is really really bright at night and that is with a series diode in that is bypassed to flash the eyes. https://www.instructables.com/id/STYRO-ROBOT-HEAD-L...

Then there are small people like my grand son may Not want drag 6 individual AAA batteries around.

Finally I'm tired of everyone mocking the 9 volt.....

It is just a matter of preference which battery best suits the purpose intended.

Consider the energy is related to weight 68g not counting a 10g holder for six AAA and only 36g for you know what......

BTW that weight information was just gleaned from an electronic scale, powered by ..... you guessed it, A 9 volt battery for over three years !

.

............. Thanks for letting me vent :-)

200px-9V_innards_3_different_cells.jpg200px-6_most_common_battery_types-1.jpg9V-15LED.JPG9V-A.JPG
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iceng

4 years ago

I suspect the 12 volt string has its own resistors and can run off 9 volts like this

But we need the current flow that feeds the 3 LED on 4.5 volts in order to size a resistor for the 9 volt battery..

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icengiceng

Answer 4 years ago

Here is the image

HEAD.bmp