how many amps will a 12v fifty node smart pixels rgb string draw

[k6ccc]

The rule of thumb and / or the published specs are a good starting point, however the real test is to power up a string at 100% full white and measure the current.  Remember that all these strings come from China, and they don't have a stellar reputation for correct specs.  Measure the actual strings and you will KNOW the current rather than THINK you know.

Last year, I rebuilt my 12 x 50 pixel tree into a 24 x 100 pixel tree.  I also moved from 5 volt to 12 volt pixels (only because I got a good deal on them from another forum member).  The original 5 volt pixels were real close to 60 mA per pixel at full white.  Powered up one of the new strings and was quite surprised to find that they were also almost exactly 60 mA per pixels.  I had not expected that and it meant I had to buy several more power supplies AND drop the pixels to 50% in the controllers.  I still managed to blow one pixel fuse midway through my 2018 show season.  I lucked out in that it was string #1 and even I didn't notice it for over a week.  By the time that I did, the end of the show was only a few days away so it was not worth hauling out the big ladder to replace it.  For 2019, I am adding the power injection that I had planned for in 2018, but ran out of time.

 

 

[jerry72]

On 4/27/2019 at 9:36 PM, uncledan said:

I've tested actual current draw on over 30,000 12v nodes.  NONE of them were 60ma(.06 amps).  That's a very safe number if someone doesn't have the capabilities to actually test them.  I find it nice to actually test items in my display and not just go off of what a vendor tells me.  

I have found that as well, however, better safe then sorry. But i am like many, i run my stuff at around 70% so i try and figure that in as well.

[jerry72]

On 4/29/2019 at 9:51 AM, DevMike said:

That's the rule of thumb for 5V pixels ONLY, not 12V.  

 

At 12 V they probably shouldn't be (but again, this depends on MFG).  At 12V the rule of thumb says they should be drawing somewhere around .034 each (100 * .034 = 3.4A +/-)

 

AGAIN - you can NOT consider voltage and/or amperage separately.  They go HAND IN HAND.  This is electricity and it is UNFORGIVING.  Please take the time to properly learn the math.  It really isn't hard.

 

Let's take the time and show a real world example.  Take a look at this strip:

https://www.alibaba.com/product-detail/High-Quality-Price-Red-Smd-5050_60798926705.html?spm=a2700.7724857.normalList.90.321d5951DMrwYV

So we have to do a little reading between the lines since this is China.  From what I can make out, this particular strip can be mfg as 12V, 24V or 48V, and is 12 pixels/m (60 pixels total) and draws 72w.

Q1:  Can a PixCon16 safely run this entire strip at 12V without injection?

Q2:  How about 24V?

Q3:  48V?

So the first thing you better notice is that this is 60 pixels, NOT 50 or 100.  Right there the rules-of-thumb need to be thrown out.  But you say 'Hey, 60 is less than 100 so at 12V I'm good."  Nope.  Read the answers below....

A1 - 12V? No way Jose!  The specs say 72w.  At 12V that is 6A (72/12 = 6).    6 > 4.  Board go BOOM.

A2 - 24V? Sure will.  At 24V this strip draws 3A (72/24 = 3).  Board is happy.

A3 - 48V? No way Jose!  WHAT?! I hear you..  You are saying 72/48 = 1.5A!  That's fine!  Now go read the PixCon16 specifications.  It is ONLY rated to 30V.  While the Amperage is good, the voltage will make board go BOOM! (page 30).

So what did we learn here? 

• Just because we have less than 100 pixels does NOT mean we can run this strip on a pixel controller at 12V!  This strip of 60 pixels consumes 6A 50% more than the board rating.  The 'rule of thumb' is completely shattered.  You MUST consult with the mfg before real world applications.
• You need to consider BOTH amperage AND voltage together.  At 24V this strip and the controller work just fine together.  At 12 things go boom.  At 48 we are below the amperage rating....
• BUT!  You can't just forget about Voltage!  At 48V this strip comes in at 1.5A which is well below the rating of 4A.  HOWEVER the voltage of 48 is well ABOVE what the board is designed to handle.

 

Is the rule of thumb worthless then?  Nope.  It is a VERY valuable tool.  It WILL handle 95% of situations.  But be sure you use that tool correctly.  It will work great for back of the envelope ESTIMATES - most pixel controllers are good for 4A per port, most will run 5v or 12v and most pixel strings you find fall into the 18w/50@5V or 35w/100@12V. 

But that does not mean:

• Your pixels don't draw MORE amps than the rule
• Your pixels don't run at something other than 5V or 12V
• Your pixel controller supports the amperage OR voltage or POWER consumed.

TL;DR:  Before applying power and destroying your pixels, your controller, or possibly the house they are attached to you need to do the REAL math.  The real math comes from the values in the specifications from the mfg of both the pixels AND the pixel controller.  Or purchase everything from us, do it the way we tell you, and don't worry about it

Not sure what pixles you are using that are 6 amps with only 60 pixels int he string. I recently just tested 15 new strings,, 100 pixels each, my max draw on all white at 100% was just over 5 amps. And that included the controller. My dumb nodes were just under 6 amps at 100% for a string of 100.

[TheDucks]

I was going to suggest the 24V, which halves the current (to ~3A). The caveat is the entire BANK is 24V (the other could be run at 5, 12 or 24. Just be veeeery careful, the plugs are the same and a 5 or 12V string will not forgive.

[LOR Staff]

19 hours ago, jerry72 said:

Not sure what pixles you are using that are 6 amps with only 60 pixels int he string.

The link is in my post.

The point is:  Do not assume that just because something has been that way in the past that it is that way in the future.  A rule of thumb is good for back of the envelope estimates BUT before you go plugging anything in, CHECK THE ACTUAL SPECS.

[jerry72]

9 hours ago, DevMike said:

The link is in my post.

The point is:  Do not assume that just because something has been that way in the past that it is that way in the future.  A rule of thumb is good for back of the envelope estimates BUT before you go plugging anything in, CHECK THE ACTUAL SPECS.

I didnt see where you wrote strip, my bad. I have no experience with those. I got several rolls of rgb but have no done an actual measurement on them yet, and wont until i get a new amp meter. Hey heres a fun fact, dont leave you volt and amp meter outside when it rains.