Author Topic: Power Supply Questions  (Read 3492 times)

Offline Gary

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Power Supply Questions
« on: July 18, 2015, 11:48:08 PM »
Okay, so I have my Falcon F16 V1 controllers in my grubby little hands, along with power supplies from HolidayCoro.

This is the power supply:
http://www.holidaycoro.com/350w-Dual-Output-Power-Supply-p/49.htm

The side of the unit states:
Input 100-120VAC 6.0A
Output +12V 29.1A

I have a spreadsheet with pixel counts, power requirements (based on HolidayCoro's estimate of 0.384 watts per pixel), and with future goals in consideration, one of my outlets would be pulling 1300 watts, which is about 11 Amps--well within the power draw of a 15 A breaker.

But looking closer at the situation now, the 1300 watt figure is on 12V, and not 120V. How do I calculate the watts (or amps) on 120V given that I'll be pulling 1300W on 12V? Would it be about 1300 x 5 since 29 Amps is about 5 times 6 Amps? That's 6500W--yikes!

Also, what gauge cable is it recommended that I use between the power supply and controller? According to http://www.solar-wind.co.uk/cable-sizing-DC-cables.html, 12V 30A at about 1 foot requires 12 gauge when 1% loss is OK, but 19 gauge is OK with 5% loss. What is considered an acceptable loss? 18 gauge cables are a dime a dozen since you can harvest them from standard computer power cables--I suppose it would be okay to double up an 18-gauge cable for both the +12V and -12V?

Offline gadgetsmith

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Re: Power Supply Questions
« Reply #1 on: July 19, 2015, 05:10:07 AM »
Watts is power. It is calculated by multiplying amps x volts. 1300 watts will draw approx 108amps at 12v on the output side of the power supply, and on the input side it will be 10.8amps at 120v.  This also ignores any loss in the power supply, so really 10.8 amps with a 90% efficiecny would be closer to 12amps.  You can also assume that unless you plan on running all pixels at full white, you'll never actually reach this theoretical power draw.

Running some numbers, you've calculated 1300watts, which at 0.384 watts/pixel, tells me you're planning to have nearly 3400 pixels. Is this correct?  That is a lot of pixels, an average of 213 pixels per output on an f-16 controller (16 outputs). You're going to need some sort of power injection/distributed power system, so in that case not all power will be going thru the f-16.   If it were, that would be 82watts, or 6.8 amps per output channel, which I don't think the f-16 (or any other controller for that matter) can handle.

Do you have more info on what props you're going to be making with these pixels?

Edit:  I see you mentioned controller(s), as in more than one!  Determining wire size to each side of the controller from the power supply will depend on how many pixels you plan to use per controller, but my guess is that you should be fine with a short run of 12 gauge wire.
« Last Edit: July 19, 2015, 05:16:58 AM by gadgetsmith »

Offline Gerry

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Re: Power Supply Questions
« Reply #2 on: July 19, 2015, 05:46:52 AM »
Hello Gary,

The calculations seem quite high on the 12v side.

As gadgetsmith said, what sort of items ie strip or string and what length are you planning to connect the controller to , for each output?
For example, 10 metres of my neon flex draws 50 watts and 1 amp.


Gerry

Offline Gary

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Re: Power Supply Questions
« Reply #3 on: July 19, 2015, 09:13:04 AM »
Watts is power. It is calculated by multiplying amps x volts. 1300 watts will draw approx 108amps at 12v on the output side of the power supply, and on the input side it will be 10.8amps at 120v.  This also ignores any loss in the power supply, so really 10.8 amps with a 90% efficiecny would be closer to 12amps.  You can also assume that unless you plan on running all pixels at full white, you'll never actually reach this theoretical power draw.

Running some numbers, you've calculated 1300watts, which at 0.384 watts/pixel, tells me you're planning to have nearly 3400 pixels. Is this correct?  That is a lot of pixels, an average of 213 pixels per output on an f-16 controller (16 outputs). You're going to need some sort of power injection/distributed power system, so in that case not all power will be going thru the f-16.   If it were, that would be 82watts, or 6.8 amps per output channel, which I don't think the f-16 (or any other controller for that matter) can handle.

Do you have more info on what props you're going to be making with these pixels?

Edit:  I see you mentioned controller(s), as in more than one!  Determining wire size to each side of the controller from the power supply will depend on how many pixels you plan to use per controller, but my guess is that you should be fine with a short run of 12 gauge wire.


So, the 12V-to-120V amp math is done by simply dividing by 10? Using an on-line watt-volt-amp calculator last night, I was getting something over 10,000 watts, which works out to a lot of amps. Perhaps it was a long day and I was just tired.

12 Amps is well within the draw of a 15 Amp breaker, but since I plan on having Air Conditioning installed in a few momths, perhaps I will ask them to also add an extra 20A GFI outlet since they're already running the power lines outside.

I should have mentioned that the power draw isn't from one light controller, but rather from one outlet/breaker. Yes, the plan is to eventually have 3400 pixels on it. The plan is to have anywhere between 108 and 84 pixels per string, in order to avoid power injection; some will merely be thrown onto bushes, some on a megatree, some arches, and some mini trees.

Offline kaos_engr

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Re: Power Supply Questions
« Reply #4 on: September 11, 2015, 09:01:56 AM »
Okay, so I have my Falcon F16 V1 controllers in my grubby little hands, along with power supplies from HolidayCoro.

This is the power supply:
http://www.holidaycoro.com/350w-Dual-Output-Power-Supply-p/49.htm

The side of the unit states:
Input 100-120VAC 6.0A
Output +12V 29.1A

I have a spreadsheet with pixel counts, power requirements (based on HolidayCoro's estimate of 0.384 watts per pixel), and with future goals in consideration, one of my outlets would be pulling 1300 watts, which is about 11 Amps--well within the power draw of a 15 A breaker.

But looking closer at the situation now, the 1300 watt figure is on 12V, and not 120V. How do I calculate the watts (or amps) on 120V given that I'll be pulling 1300W on 12V? Would it be about 1300 x 5 since 29 Amps is about 5 times 6 Amps? That's 6500W--yikes!

Also, what gauge cable is it recommended that I use between the power supply and controller? According to http://www.solar-wind.co.uk/cable-sizing-DC-cables.html, 12V 30A at about 1 foot requires 12 gauge when 1% loss is OK, but 19 gauge is OK with 5% loss. What is considered an acceptable loss? 18 gauge cables are a dime a dozen since you can harvest them from standard computer power cables--I suppose it would be okay to double up an 18-gauge cable for both the +12V and -12V?

The power supply you show provides 350 W max. output (12V * 29.1A = 349.2Watts) using 120VAC * 6.0A = 720Watts in; thus, it's not even 50% efficient.   Efficiency % = (Power out)/(Power In) * 100 = 349.2/720 * 100 = 48.5% efficient.

Using four (4) of these power supplies, the input AC circuit needs to provide:

    120VAC * 24A = 2880Watts

to obtain the DC output:

    12VDC * 116.4A = 1396.8Watts)

Thus, two (2) 15Amp 120VAC circuits should be used to provide the required input supply for you design.
 
Kaos Engineer

Offline jnealand

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Re: Power Supply Questions
« Reply #5 on: October 01, 2015, 12:16:46 PM »
Piggybacking on this thread.  I have a pixel tree with 18 strands of 61 TM1804 nodes plus a 100 TM1804 node RGB star.  On a thread somewhere I found that typical nodes draw about .06a each.  So

18 x 61 x .06 = 65.88a at 12v
1 x 100 x .06 = 6a at 12v

I had the 18 strands hooked up for testing last week using a single 30a power supply which was plugged into a Kill a Watt.  Using the hardware test I was drawing 2.8 - 3.9 amps depending on the color the cycle was in.  The fan on the PS was humming like a helicopter.  I still need to add the star to the mix.  While it appears to be within an acceptable range I plan to add a second PS to the F16 I am not an electrician so just asking other more knowledgable folks to verify my thinking.

A second question is what is an acceptable wire to use for the PS to F16.  I am using 12ga household wire but would like something more flexible.  Would 14ga stranded speaker wire be ok?
Jim Nealand
Kennesaw, GA all Falcon controllers, all 12v Master Remote Multisync with Pi and BBB P10 and P5

Offline Jeffl

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Re: Power Supply Questions
« Reply #6 on: October 01, 2015, 12:28:29 PM »
I tested the nodes (DIYLEDExpress) I have with a multimeter the other day and they tested at a little over half what the HolidayCoro specs said (same node type).  I'm assuming the nodes are very similar so I would check them with a multimeter if you want to be sure.  Of course using the higher numbers will be safe as well.

Offline txag2008

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Re: Power Supply Questions
« Reply #7 on: October 01, 2015, 03:18:14 PM »
Quote
Piggybacking on this thread.  I have a pixel tree with 18 strands of 61 TM1804 nodes plus a 100 TM1804 node RGB star.  On a thread somewhere I found that typical nodes draw about .06a each.  So

18 x 61 x .06 = 65.88a at 12v
1 x 100 x .06 = 6a at 12v

I think that information is pretty far off.  You wouldn't be using a single 30A PS if you had 70A+ worth of lights.

The typical TM1804 node draw is .3W (.025A).  The correct calculation should be below.
18 x 61 x .3 = 329.4w @ 12v = 27.45A
1 x 100 x .3 = 30w @ 12v = 2.5A

 

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