0

Powering multiple, full-bright 144/m neopixel strips
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Powering multiple, full-bright 144/m neopixel strips

by Triene on Tue Apr 10, 2018 3:51 pm

Hello all, and thanks in advance for any advice.

I've been researching this topic for a while now, but I really know very little about power, so I've only made some progress. Hope you can help.

I'm doing a project where about 2.5m of 144/m Neopixel strips need to, among other things, be full-brightness white for periods of time (not all day every day, but on/off for different amounts of time over the day). I realize this will be a significant power draw and need to supply the power safely. They could be at as little as 95% brightness, but no less than that, or it won't be bright enough for the application.

I've done the calculations and found that this amounts to about 360 pixels, which need over 20 amps to shine that brightly.

What I haven't been able to determine is:

    1. Should I use multiple power supplies, or one? If multiple, should I put one on each end of the strip and simply cut the 5V connection on the light strip in the middle somewhere? Will using two supplies change the amps that the supplies can use?

    2. Should I get a 5V, 30A power supply? Will this be correct and sufficient?

    3. Are there other components I need to consider? I saw in the Uber guide that they recommend adding a large capacitor (1000 µF, 6.3V or higher) across the + and -. Is this type of capacitor still recommended, and will it be sufficient? I don't fully understand how they work (I mean, I understand the idea, but I can't put practical numbers to it), so I wouldn't know how to pick out a new one if I needed one.

    4. How should I consider wire gages? In other neopixel projects, I used I think 22ga split wire. Will I need a lower gage wire, and how can I calculate this?

I feel like the answers to these questions are out there floating around, but I can't seem to figure out what they are on my own, so I apologize if any of this seems redundant to you. I'd really appreciate the advice, including if there's something I didn't mention here that you think I should consider!

Triene
 
Posts: 7
Joined: Fri Mar 09, 2018 12:29 pm

Re: Powering multiple, full-bright 144/m neopixel strips

by adafruit_support_bill on Tue Apr 10, 2018 4:08 pm

1) Either way will work. If you use multiple supplies to power different sections, you should cut the 5v connection between the different sections. In any case, you will need to run multiple power feeds. I'd recommend one per meter at least.
2) A single 30A supply should be sufficient. But you will still need to feed power at multiple points on the strip as noted above.
3) A large cap on the power supply will protect against power supply startup surges. The exact value is not critical. We recommend 100uF/63v or higher. And, for safety, it is wise to fuse each power feed using a fuse appropriate for the wire gauge.
4) That depends somewhat on the length of the runs and how you divide up the power feeds. There are charts of recommended wire gauges. https://www.powerstream.com/Wire_Size.htm

adafruit_support_bill
 
Posts: 67862
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering multiple, full-bright 144/m neopixel strips

by Triene on Wed Apr 11, 2018 9:29 am

adafruit_support_bill wrote:2) A single 30A supply should be sufficient. But you will still need to feed power at multiple points on the strip as noted above.


I appreciate all of the answers! That really clarifies a lot for me.

Regarding your point about #2, how would this work exactly? You simply have multiple power cables coming from the power supply, and then attach them at different points as already described?

Is there anything inherently better or worse about that vs. using two totally separate supplies? I'd really prefer to use a single supply if possible, but I want to be safe above all else.

Thanks again. Hopefully this topic is helping others with similar questions.

Triene
 
Posts: 7
Joined: Fri Mar 09, 2018 12:29 pm

Re: Powering multiple, full-bright 144/m neopixel strips

by adafruit_support_bill on Wed Apr 11, 2018 9:46 am

You would have multiple cables from the main supply feeding power to points along the strip.

From a safety perspective, one argument for multiple supplies is that a short circuit involving 5A is less dangerous than one involving 20A.
But you can achieve a similar thing using 20A supply with 4 feed lines individually fused for 5A each.

adafruit_support_bill
 
Posts: 67862
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering multiple, full-bright 144/m neopixel strips

by Triene on Wed Apr 11, 2018 10:29 am

adafruit_support_bill wrote:You would have multiple cables from the main supply feeding power to points along the strip.

From a safety perspective, one argument for multiple supplies is that a short circuit involving 5A is less dangerous than one involving 20A.
But you can achieve a similar thing using 20A supply with 4 feed lines individually fused for 5A each.


Okay, understood. Thanks again for the help and clarifications.

Triene
 
Posts: 7
Joined: Fri Mar 09, 2018 12:29 pm

Please be positive and constructive with your questions and comments.