WS2812 leds, best method for power distribution

Not sure the best forum for this, but I want to run 450 WS2812 leds (30 led per meter strips) in a single strip, so total length 15m.

So max current is going to be 27A.

I read that ideally you should have a power connection every meter but this isn't going to be really possible.

I don't know what voltage drop there is on a flexi strip, so not sure how far is reasonable between power connections.

I'm not sure if having power distribution is best done with DC 5V and one big PSU (a PC PSU will do 5V at 35A for a twenty quid) or several smaller PSU's distributed with mains running out to them. (A much more expensive option).

If I go with a single PC switchmode, I would have some long cable runs, so I need to know how much voltage drop is noticeable. Worst case approx 8.5m

The leds are going to be arranged in a rectangle 2.2mx5.3m so if the psu is a meter away from one corner, the furthest corner will be 8.5m away.

I guess brightness differences can be tuned out in software or I could make all the power feeds 8.5m long to get even voltage drops.

Any suggestions?

The strips are not designed for really high currents, so you definitely need to have the power connected at multiple places. The chips work on 3.5V to 5.3V, so voltage drop of your power distribution is not so big a deal unless you are using really small wires.

Can you arrange the PSU to be as centrally located as possible?

I measure 0.17ohms per meter on the strips I have, but as the current drops along the length, it's not so easy to measure the drop...

I think I'll just have to buy a few meters and do some tests to see if the drop in intensity over a few meters is noticeable.

richardtheboffin: I read that ideally you should have a power connection every meter but this isn't going to be really possible.

Of course it is, and that's exactly how you do it.

You run a piece of power cable along with the strip, arguably the same sort of power cable that is used to wire your house, though this would have unnecessarily heavy insulation, and you cross connect this each metre, to the strip.

In fact, the sort of "monster cable" used for loudspeaker connections would be a better choice - even heavier conductors but not quite as heavy insulation.

Paul__B: Of course it is, and that's exactly how you do it.

You run a piece of power cable along with the strip, arguably the same sort of power cable that is used to wire your house, though this would have unnecessarily heavy insulation, and you cross connect this each metre, to the strip.

In fact, the sort of "monster cable" used for loudspeaker connections would be a better choice - even heavier conductors but not quite as heavy insulation.

I guess 1mm mains cable at 0.02ohms per meter will ok. 15 runs of it will be quite a big bundle! Speaker cable might be more manageable.

Actually you mean run 2.5mm mains or speaker cable in parallel with the led strip, joining every meter, rather than having a run back to the PSU every couple of meters. So there will only be one (or two if I make a ring) cable running back to the PSU. It just has to carry 27A at 5V without dropping too much, but only the bit at the PSU will have the full 27A going through it.

A ring would half the drop on the cable.

2.5mm is .0075 ohms per meter so the drop should be fairly minimal.

That makes more sense!

Now you are getting it! Not (necessarily) separate runs but joined at each metre, and a ring would be good.

I would go for at least 2.5 mm2.

Yes I had the wrong end of the stick there for a bit!

I have ordered 15m of leds, so I'll have a look into the best platform for controlling them. I have a spare Teensy and a few RPi's which should do it.

Thanks for the input!