Aquarium Lighting Beam: Power Supply for 4x 10W COB LEDs - 12V, 900mA, Stabilized & 40W Options

Question

I am planning the construction of an aquarium lighting beam based on four LEDs, each of which has the following parameters: I am looking for a power supply for them. On the auction site I found one for PLN 15: And now the questions: 1. Is such a power supply suitable? Is the fact that it has an...

krzysiek_krm · Accepted Answer

Hello, In a parallel connection it is identical tension at the terminals of each load. The current flowing through each load is due to its equivalent resistance (generally impedance), it is due to Ohm's law. Current in series connection every load is identical, because where would it disappear or from where it would suddenly appear. Maybe I was too jargon. The power supply may be a regulator voltage then it holds the voltage and the current is whatever, within real limits, of course, it can be a regulator current , then it holds the current and the voltage is whatever, also within real limits. Sure, we're just not talking about powering the motherboard, but the LED. The diode is not lit because we will give some tension but because it flows defined by it electricity . The voltage-current characteristic of the diode in the working area has a very low dynamic resistance, small changes in voltage correspond to very large changes in the current, it is enough to slightly increase the supply voltage of the diode and the current can increase significantly above the allowable. Therefore, power supplies for LEDs have the nature of a current source, they keep the current (what is needed) and the voltage is what comes out. Sure, as I mentioned, we do not power the computer, but the diodes. Let's assume that we supply parallel connected diodes, in your case one has a nominal voltage of 9 V and the other 12 V. If you set the power supply to 9 V, the 9 V LED will be lit and the 12 V LED will be dark, if you set 12 V, the 12 LED will light. V, but in the 9V diode, due to the very low dynamic resistance, a current of say 100A will start flowing and the diode will fly into the air. LEDs have a native operating voltage of 3 V, the higher voltages are due to the fact that manufacturers for technical reasons connect them in series in several or a dozen. Connect your LEDs in series. Apply special power supply for LEDs, which is a regulator current , in your case 900 mA and can regulate this current with an output voltage equal to the voltage of four LEDs connected in series, such power supplies have a rather wide range of this output voltage. Adopt a dimmable power supply. best regards

krzysiek_krm · Answer

Hello,
the driving force behind the LEDs is the flow of electricity.
You should therefore connect them in series, getting a voltage from 36 V to 48 V, according to the catalog data. In series connection, a current of 900 mA will flow through them, also according to the data.
The whole thing should be supplied with current 900 mA LED power supply that can get an output voltage of 36 V to 48 V, for some safety, say 30 V to 54 V.
Such a power supply works as a current source, in your case with a capacity of 900 mA, the voltage at its output will be determined by the voltage drop across the diodes connected in series, in short, the power supply determines the output current, and the LEDs determine the output voltage.
Parallel connection of diodes is not recommended. They have a certain production voltage spread, in your case from 9 V to 12 V, so in practice the diode with the lowest voltage that it determines at the output will be lit, the diodes with a higher voltage will shine weakly or not at all. With so much power, it makes no sense to use equalizing resistors.

best regards

Lockheed · Answer

I learn strange things. Until now, I thought that:

1. Parallel connection will provide equal current to each of the elements, while the series center elements will have less current than the outer ones.
2. Each power supply is current... Are there any other electricity?
3. Since the receivers operate on 12V, they require such a current, and that connecting a higher one will burn them, because the power supply determines the voltage it sends, and the receivers decide how many Amps they will take from it.
4. The A value given by the power supply is irrelevant as long as it is equal to or higher than the sum A of the receivers. I am not an electrician, but I know computer science and hardware well and that's where it works.

Could you briefly comment on these points?

By the way, I will also ask if
- are the 36V or 12V diodes "better" in some way than the other?
- if I wanted to use a dimmer (simulating dawn and dusk, or simply the possibility of reducing the amount of generated light), will installing a voltage limiter between the socket and the power supply will work, or must it be somewhere behind the power supply?

Lockheed · Answer

Thanks for the detailed explanation.

Due to higher temperatures and complications with the power supply, I wonder if the 2835 LED strip would be a better choice. When cutting 3 meters of such tape into 4 strips, connect them in series (because the same principle applies here as with COB diodes) or in parallel ( because they work differently)?
I am asking because I read somewhere that with long tapes the diodes inside may glow dimly.

krzysiek_krm · Answer

There may be a tape.
The strip has a slightly different design, it consists of a large number of "small" diodes, each of them through a series resistor that sets the current of that particular diode, connected to a common power rail, for example 12 V.
So the pieces of tape should be joined parallel to a common power supply which is a regulator voltage , for example 12 V.
The diodes in the tape usually glow less at the end due to the voltage drop across the power rails, which are usually rather thin traces.
If you want to dim, between the power supply voltage 12 V and with the tape, turn on the LED brightness regulator 12 V, operating on the PWM principle, modulating the LED supply voltage.

Lockheed · Answer

And what about the electricity consumption / cost of these two solutions? LED strip - 3 meters: COB diodes - 4 pieces: Will one of these solutions be noticeably more energy efficient than the other?

krzysiek_krm · Answer

At comparable brightness, energy consumption will be greater for the ribbon.
First, there are resistors on which some energy is lost, i.e. converted into heat.
Secondly, usually the luminous efficiency of "small" LEDs used in the tape is lower, although it depends on the luminous efficiency of these 10 W LEDs, if they are from a reputable manufacturer, they have high efficiency, if "noname" - hard to say.
However, the energy problem is, in my opinion, not very important. Suppose the difference is 10 W, if you keep shining it will be 240 Wh a day, which is 7200 Wh = 7.2 kWh a month, that's about 4 zlotys, or less if you have a reduced tariff.

Lockheed · Answer

It really makes no difference.

For 10 W COBs, Current: 9 - 12V; 900ma, you advised me 900ma 30V to 54V power supply.
However, I have a problem with finding one that would meet these parameters.

Which power supply should I choose for up to four 30-36V COBs; 300mA? Will it be 120-144V? This is probably a dangerous voltage.

Aquarium Lighting Beam: Power Supply for 4x 10W COB LEDs - 12V, 900mA, Stabilized & 40W Options

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