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[moved] want to make charger and power supply for led strip

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Newbie level 3
Aug 16, 2015
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Ok, so I'm completely new to this forum. So please bear with me.
I also dont know if this is the correct secrion to post my question. So please move it or yell at me if i need to move it. ;-)

Ok, so lets this party started.

I need to build a 12volt to 12 volt battery charger, maintainer.
Think UPS system for a PC, but the size of a beer can or smaller if possible. Prefer as small as possible as my space to install is very tight.
All this thing needs to power is 90" of this strip, for 4-6 hours. Both constant and intermittent.
Need it to turn on the led's when the primary vehicle battery is disconnected from this device.

16.4 Feet 12V 300LED 5050 SMD IP65 Waterproof Flexible Lamp Light Strip (White)

Both the device and battery needs to beable to handle harsh environments, like under hood inside a engine bay.
Also needs to be simple, cheap and easy for me to build.

Big thanks to anyone of you guys that can help me with this project.

Get real.

approx. 90 " of a 5m reel at 50 LEDs/m will require a typical Car battery of 40Ah to power 2.3m or 160LEDs at ~120mA per string of 3 or 6.3A for 6 hours.

Cheap, simple but heavy.

What are the R values per string and how many per string of 3 LEDs?

R value is 390.
If 6 hours is not feasable, lets try for a max of 4 hours.
Was hoping to use a high output RC helicopter battery or a sealed battery like is used in kids power wheels toys.

There are car battery boosters which put out higher than 12V. A versatile unit might come with a plug for the cigarette lighter, as well as clips for connecting to battery terminals.

Pictured is a small one. Larger units are available at higher prices.


I need a 12 volt to 12 volt UPS.

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