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continuously for one hour, or 1.3 Amps for 2 hours, and so forth. In reality, it’s not quite linear like that; most batteries

have disproportionally shorter run times with a heavy load. Also, most batteries won’t take kindly to being

discharged in an hour — this can even be dangerous! Select a battery sufficiently large that it will take at least a

couple hours to run down. It’s both safer for you and better for the longevity of the battery.

I need to power LOTS of NeoPixels and don’t have a power supply that large. Can I use several smaller ones?

Maybe. There are benefits to using a single supply, and large power supplies are discussed below. “Non-optimal”

doesn’t necessarily mean “pessimal” though, and we wouldn’t discourage anyone from using what resources they

have.

If you go this route, the key is to have all of the ground pins among the strips connected in common, but the +5V

from each power supply should be connected only to one length of NeoPixels — those should

not

all be joined.

Every power supply is a little different — not

precisely

5 Volts — and this keeps some from back-feeding into others.

Giant Power Supplies

Adafruit offers 5V DC power supplies up to 10 Amps. This is usually sufficient for a couple hundred NeoPixels or more.

For

really

large installations, you’ll need to look elsewhere.

One possibility is to repurpose an ATX computer power supply. The nice beefy server types often provide up to 30

Amps. Some minor modifications are needed…Google around for “ATX power supply hack.” Note that the ATX 5V rail

can be very unstable if there's no load on the 12V rail!

Even larger (and scarier, and much more expensive) are laboratory power supplies with ratings into the

hundreds

Amps. Sometimes this is what’s needed for architectural scale projects and large stage productions. And occasionally

we get requests for help…

Please note that projects of this scale are potentially very dangerous, and the problems of power distribution are

fundamentally different than hobby-scale projects. As much as we enjoy helping our customers in the forums, they are

for

product technical support

and not full-on

engineering services.

If you’re developing a project of this scope, hire a

professional electrician with experience in high-power, low-voltage systems such as photovoltaics or large RVs and

boats. This is no charade.

Distributing Power

The longer a wire is, the more resistance it has. The more resistance, the more voltage drops along its length. If voltage

drops too far, the color of NeoPixels can be affected.

Consider a full 4 meter reel of NeoPixels. With 5V applied at one end of the strip, for those pixels closest to this end,

power traverses only a few inches of copper. But at the far end of the strip, power traverses

8 meters

of copper — 4

meters out on the +5V line, 4 meters back on the ground line. Those furthest pixels will be tinted brown due to the

voltage drop (blue and green LEDs require higher voltage than red).

Pro Tip: NeoPixels don’t care what end they receive power from. Though data moves in only one direction, electricity

can go

either way.

You can connect power at the head, the tail, in the middle, or ideally distribute it to several points.

For best color consistency, aim for 1 meter or less distance from any pixel to a power connection. With larger NeoPixel

setups, think of power distribution as branches of a tree rather than one continuous line.