Transformer requirement for LED lights

[Aquacrazed]

Hi, I am trying to figure out the transformer I need to hook up 2 LED strips (3 watts each) and 1 LED bar (16 watts). So that's a total of 22 watts of LED's. I have a 13.5V transformer (see picture) that came with my LED bar and I am planning on connecting everything to this through my dual ramp timer (http://current-usa.com/accessories/dual-ramp-timer/). Any advice?

Thanks!

https://flic.kr/p/WP4J69

https://farm5.staticflickr.com/4300/35975867706_3dcecdc691_o.jpg (https://flic.kr/p/WP4J69)

[mike31154]

Too small to run both. If I see the photo correctly it has 1000 ma output. That's 1 amp. Multiply the 1 amp by voltage (12) and max power = roughly 12 watts about half of what you're trying to run. Ohm's law.

[Aquacrazed]

Too small to run both. If I see the photo correctly it has 1000 ma output. That's 1 amp. Multiply the 1 amp by voltage (12) and max power = roughly 12 watts about half of what you're trying to run. Ohm's law.

Thanks for the reply Mike. The output is 1500 ma and 13.5v. So according your calculation (1.5 x 13.5) that would be a max power of 20.25 watts. Is that right? But that's still a bit shy of the 22 watts needed. My dual ramp timer support 24v, so should I get a 24v transformer?

I'm pretty new to this stuff and I'm wondering how these 2 strips and the bar will handle the power if I get a 24v. For example one LED strip only needs 3 watts, if I hook it up to a 24v transformer would it burn out or does it only draw just the required 3 watts?

[calo247]

Thanks for the reply Mike. The output is 1500 ma and 13.5v. So according your calculation (1.5 x 13.5) that would be a max power of 20.25 watts. Is that right? But that's still a bit shy of the 22 watts needed. My dual ramp timer support 24v, so should I get a 24v transformer?

I'm pretty new to this stuff and I'm wondering how these 2 strips and the bar will handle the power if I get a 24v. For example one LED strip only needs 3 watts, if I hook it up to a 24v transformer would it burn out or does it only draw just the required 3 watts?


you will need to get a transformer with the same output voltage as the LED's

[Aquacrazed]

Bump?

[mike31154]

Never advisable to overload a power supply, fire hazard. If the LED bar came with the 13.5 volt power supply, running it with a 24 volt supply could also cook it. Not enough info on your lights to provide more advice. Check data plate on lights for voltage rating. Get a larger 13.5 volt supply.

[mike31154]

Any of your lights on the list of those compatible with the timer you linked to?

[scoobs]

yeah I can't dim my leds, so that timer would be useless for my setup.

[Aquacrazed]

There is no data panel in the LED bar (stock light I got with the tank kit, Fluval Evo 13.5) or the strips. For the LED bar the only info is in the transformer (above picture - 13.5v, 1500ma). For the strips, the box simply says 3 watts but also says I can connect 3 of them to a 12v power supply using a splitter.

The 2 LED strips are compatible with the dual ramp timer. The LED bar is not on the list. They only list Current USA products on the list.

What power supply would you recommend?

[sobe]

The fluval evo 13.5 kit came with a 16w stock light. So your two 3W might not be the stock light.

The current usa ramp timer has list of compatible led bars. Depending on your unit it might not dim. As it's dependent on the driver used in the LED unit.

Do you have pictures of your led bars, including their connecors? We can possibly identify which manufacturer it is from.

[Aquacrazed]

The 3 watt lights (actinics) are Current USA lights, I have 2 of them that I will be connecting through a splitter.

[calo247]

you will need a 13.5v power supply if that is what came with the bar. your other leds state they can run off a 12v supply so i would get a 12v supply, it will be well above the cut-off voltage for the bar and should run it fine. just get a big enough supply to power all of it, just add up the wattage of all the leds you need to run and double it (power supplies run most efficiently around 50-60% load)

be very careful with dimming leds. it is critical you have a driver that can handle dimming, most cheap ones can not

[Aquacrazed]

you will need a 13.5v power supply if that is what came with the bar. your other leds state they can run off a 12v supply so i would get a 12v supply, it will be well above the cut-off voltage for the bar and should run it fine. just get a big enough supply to power all of it, just add up the wattage of all the leds you need to run and double it (power supplies run most efficiently around 50-60% load)

be very careful with dimming leds. it is critical you have a driver that can handle dimming, most cheap ones can not

Thanks for the info calo247. So the total wattage I need is 20.25 and 19.5v. If I get a 24v power supply, would this be ok?

About the driver, my Current USA dimmer supports the LED strips but I'm not sure about my Fluval LED bar. How would I know if it needs a driver? I've run it (just the Fluval LED bar since it came with it's power supply) through my dimmer a few days now and seems to be working fine so far.

[calo247]

wattages you add, you dont add the voltages together, a 24v supply will not work, you need a supply with the same voltage as your leds, and if they are different then you cant run them together off the same supply.

what is the voltage requirment of the strips? how did you get 19.5V?

from what i can gather (correct me if i am wrong) you are trying to run

- 1 led bar that came with a power supply rated at 13.5V
- 2 led strips that are rated at 12v

[calo247]

the drivers are in the led strips, you cannot change them, they either support dimming or they dont, if you cant determine if the bar is dimmable on its own i personally would not trust putting a dimmer on it.

[Aquacrazed]

wattages you add, you dont add the voltages together, a 24v supply will not work, you need a supply with the same voltage as your leds, and if they are different then you cant run them together off the same supply.

what is the voltage requirment of the strips? how did you get 19.5V?

from what i can gather (correct me if i am wrong) you are trying to run

- 1 led bar that came with a power supply rated at 13.5V
- 2 led strips that are rated at 12v

The strips (rated at 3 watts each, don't know the voltage, has 4 lights per strip) can be connected (both) to a 12v power supply.

Sorry I miscalculated the vottage, 19.5v is wrong.

Here's what I know:

Fluval LED bar: 13.5v 1500ma
Current USA LED strips: 3 watts each (6 watts total). They say 1 - 3 of these strips can be connected to a 12v power supply through a splitter.

[calo247]

okay, then the led strips are rated at 12v, they would be connected in parallel.

your going to need a 12v power supply rated at at least 26.25 watts (2.2A at 12V)

[mike31154]

I just had a look at the instructions for the Dual Ramp Timer. At the top of page 4 under the fixture compatibility heading it includes "Most 12-24VDC LED fixtures not exceeding 120 watts (@24V) with a compatible DC barrel jack connector"

This means all of the LEDs you intend to hook up to it should work fine, the Timer will modulate the output accordingly. Both input & output for the Timer are listed as 12-24VDC. Provided the power supply you hook up to the Timer has sufficient wattage to run your lights it can be anywhere from 12-24 volts. At the moment your LED wattage adds up to roughly 20, so go shopping for any 12-24 volt power supply that can provide at least 30 watts. It's always better to have a little more headroom rather than run a power supply at its maximum rated output and the price difference isn't that much. An oversized power supply will run much cooler.

[calo247]

no you can not just run any 12-24v supply, a 24v supply WILL fry the leds, the dimmer module has no idea what the led max voltage is... the dimmer is intended to be used with a light that comes with the appropriate power supply, and cut the voltage with 100% being running the lights at their normal undimmed output.

if you have a 24v supply on the input 100% will be 24v output and will fry the 12v rated leds. please do not get a power supply rated at more than 12v

trust me, i am an electrician

[Aquacrazed]

I just had a look at the instructions for the Dual Ramp Timer. At the top of page 4 under the fixture compatibility heading it includes "Most 12-24VDC LED fixtures not exceeding 120 watts (@24V) with a compatible DC barrel jack connector"

This means all of the LEDs you intend to hook up to it should work fine, the Timer will modulate the output accordingly. Both input & output for the Timer are listed as 12-24VDC. Provided the power supply you hook up to the Timer has sufficient wattage to run your lights it can be anywhere from 12-24 volts. At the moment your LED wattage adds up to roughly 20, so go shopping for any 12-24 volt power supply that can provide at least 30 watts. It's always better to have a little more headroom rather than run a power supply at its maximum rated output and the price difference isn't that much. An oversized power supply will run much cooler.

Thank you Mike!

[Aquacrazed]

no you can not just run any 12-24v supply, a 24v supply WILL fry the leds, the dimmer module has no idea what the led max voltage is... the dimmer is intended to be used with a light that comes with the appropriate power supply, and cut the voltage with 100% being running the lights at their normal undimmed output.

if you have a 24v supply on the input 100% will be 24v output and will fry the 12v rated leds. please do not get a power supply rated at more than 12v

trust me, i am an electrician

Thanks! I will get a 12v power supply rated for at least 30 watts

[mike31154]

no you can not just run any 12-24v supply, a 24v supply WILL fry the leds, the dimmer module has no idea what the led max voltage is... the dimmer is intended to be used with a light that comes with the appropriate power supply, and cut the voltage with 100% being running the lights at their normal undimmed output.

if you have a 24v supply on the input 100% will be 24v output and will fry the 12v rated leds. please do not get a power supply rated at more than 12v

trust me, i am an electrician

So am I. The dimmer/timer will limit the output current to the LEDs regardless if the input voltage is 12 or 24 volts. But you don't have to trust me, get a 12 volt supply & be happy. Wonder how your LED bar hasn't fried with the 13.5 volt supply. If you have a notebook computer it most likely has a 24 volt supply with sufficient power, give that try.

[calo247]

So am I. The dimmer/timer will limit the output current to the LEDs regardless if the input voltage is 12 or 24 volts. But you don't have to trust me, get a 12 volt supply & be happy. Wonder how your LED bar hasn't fried with the 13.5 volt supply. If you have a notebook computer it most likely has a 24 volt supply with sufficient power, give that try.

there is multiple problems with this statement, first the timer doesn't really "limit" output current (as its a PWM based dimmer), the leds just draw what they need (this is why i can plug my phone into the same outlet as a fridge can use lol). and then you talk about voltage, which is completely different than current... it matters what the input voltage is there is no way that dimmer has any voltage regulation in it to reduce it to what the leds require, the only way to do this on a DC circuit is to expel it as heat, you can not use a transformer to do it, and i do not see it being able to do that with out a heatsink of some sort (even if this was the case it would be impossible for the dimmer to just determine what the leds are rated for, there for there would be some sort of way of setting the output voltage).

but what i just said does not even really matter because it says on the product page it is a PWM based dimmer so they do not use voltage reduction to get the dimming effect.

ya the 13.5v supply wont fry the strip, but i am sure a 24v one would, plug anything into double the rated voltage and let me know how that goes.

[calo247]

you could also use a switching supply to cut DC voltage but that introduces it own set of problems and would still require the output voltage to be set

[Aquacrazed]

12v it is :) I ordered this one: https://www.amazon.ca/gp/product/B01FFY9CDQ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

12v 5A

[mike31154]

That should work fine. With respect to how the Dual Ramp Timer works, none of us have the internal circuitry so we can only guess at how it really functions. If you look at page 1 of the instructions, the diagram shows "12-24VDC Transformer" for both hook up configurations. There are no warnings or cautions regarding using one voltage over the other. There are plenty of DC to DC voltage converter circuits that can reduce a given voltage without the use of large heat sinks or heavy transformer coils, particularly for low power applications such as this. Could be as simple as a zener voltage regulator diode, or more complex. In any case, getting the 12 volt supply is your best bet. You can use it on your LEDs without the Dual Ramp Timer if you wish.

[calo247]

That should work fine. With respect to how the Dual Ramp Timer works, none of us have the internal circuitry so we can only guess at how it really functions. If you look at page 1 of the instructions, the diagram shows "12-24VDC Transformer" for both hook up configurations. There are no warnings or cautions regarding using one voltage over the other. There are plenty of DC to DC voltage converter circuits that can reduce a given voltage without the use of large heat sinks or heavy transformer coils, particularly for low power applications such as this. Could be as simple as a zener voltage regulator diode, or more complex. In any case, getting the 12 volt supply is your best bet. You can use it on your LEDs without the Dual Ramp Timer if you wish.

there are no warnings because they give you the list of compatible lights and they intend for you to use the power supply that is included with those lights.

if you ever find a transformer that works on DC you should notify the world, you would be a very rich man

there is no such thing as a zener voltage regulator diode, in order to get a voltage drop out of a zener diode you need to introduce a current limiting resistor (ie. heat) before it, and you would need to have so many of them as they have a very tight tolerance, so you would need differently rated one for each level of dimming you wanted.

in terms of the circuit we are not really guessing, it says its pwm based, which makes sense as it is really the most efficient


hopefully the adapter comes with the same size barrel connector, it would suck to have to lop it off

[Aquacrazed]

Ok so I got the 12v 5A adaptor and my Fluval light bar is not as bright now. It is a fair bit brighter with the 13.5V 1500ma power supply it came with.

[mike31154]

Are you running the light through the timer/dimmer or straight off the power supply?

[Aquacrazed]

The dimmer doesn't seem to have any effect, it simply seems to just pass the current. So weather I connect it through the dimmer or not, the brightness is more when I connect it with the 13.5v power supply.

[mike31154]

Since the voltage vs current relationship for a diode or LED is nonlinear, the fact that your LED runs brighter with the 13.5 volt vs 12 volt supply makes sense. What doesn't make sense is that the "dimmer doesn't seem to have any effect". Not sure I'm fully understanding that part of your statement.

Depending on the load connected to a power supply, especially a smaller one loaded to near max, it will drop to a lower voltage level. That is, if you were to measure the voltage output of your 13.5 volt supply while it is under close to maximum load, I suspect you would read less than the rated 13.5 volts.

Here is a graphic of the voltage vs current curve of a LED or diode.

http://www.amperor.com/products/led/images/led_i_v_curve.jpg

As you can see as the voltage nears the rated/maximum forward voltage of about 3 volts for the diode, the current rises sharply. This is why using a power supply of the correct voltage is so important, or you risk cooking your diode. However, something as simple as resistor in a circuit running a LED can keep the current at a safe level by dropping the voltage available to run the LED to its rated value. This is not efficient since the resistor wastes power & creates heat in doing so. This is why PWM (pulse width modulation) is commonly used to dim and control the current to LEDs, it is more efficient. That doesn't mean you can't also include components such as resistors and zener diodes in conjunction with PWM circuitry to help sense & control both voltage and current in designing your hardware. Often tradeoffs are made in efficiency vs simplicity of design in most of these components. This is why I was suggesting that it may be possible to use a 24 volt supply feeding your dimmer to safely run your 12 volt LEDs. Again, that may not be an experiment you wish to carry out. If I'm wrong, you could cook your lights.

[Aquacrazed]

I see, I think I will contact Fluval and ask them if a 24v power supply will work with this LED bar. I contacted Current USA, they say a 24v power supply will work for their LED strips.

[calo247]

you hit the nail on the head with the current graph, that is a pretty steep curve, do the strips use the Cree XR-E leds?

[calo247]

are these the strips you have?

http://current-usa.com/aquarium-led-lights/truelumen-pro-led-strips/truelumen-pro-led-striplights/

if so it is really weird it came with a 13.5v supply when on their site it says it is powered by a 24v one, it even lists a part number for one.

you did mention before that the box said it could be hooked up to a 12v supply, was this a typo?

[Aquacrazed]

LED strips: http://current-usa.com/aquarium-led-lights/truelumen-pro-led-strips/truelumen-led-strips/
They don't come with a power supply, they say they can ben connected to a 12 - 24v

The 13.5v power supply came with the Fluval LED bar (it's the light that comes with the Fluval Evo 13.5 kit)

[calo247]

i cant see where it says it can be connected to a 24v supply, only talks about a 12v one, and supply in the parts list is a 12v one. maybe the person you talked to got confused on what strip you had maybe?

[mike31154]

Error, delete.

[Aquacrazed]

i cant see where it says it can be connected to a 24v supply, only talks about a 12v one, and supply in the parts list is a 12v one. maybe the person you talked to got confused on what strip you had maybe?

I got a reply from Current USA:

The 24v transformer compatible with the Truelumen actinc strips can be found below:

https://www.amazon.com/TrueLumen-24-Volt-60-Watt-Pro-LED/dp/B004QE69WY/ref=sr_1_1?ie=UTF8&qid=1500649882&sr=8-1&keywords=current+usa+24v+60w

[Aquacrazed]

Also just today I got a reply from Fluval:

We do not recommend you use a higher powered power supply as it will damage the unit and void your warranty.

[Aquacrazed]

I was looking on Amazon and noticed they have a used single ramp timer (https://www.amazon.ca/gp/product/B00FDV1AFA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) for $20. I decided to buy it and then use my Fluval LED bar though it and then use the dual ramp timer for my Current USA LED strips (actinics).

Thanks for all the help guys.

[calo247]

I got a reply from Current USA:

The 24v transformer compatible with the Truelumen actinc strips can be found below:

https://www.amazon.com/TrueLumen-24-Volt-60-Watt-Pro-LED/dp/B004QE69WY/ref=sr_1_1?ie=UTF8&qid=1500649882&sr=8-1&keywords=current+usa+24v+60w

that says its for the truelumen PRO not the normal truelumen light, but i guess it does not matter now that you ordered the other timer.