What does stronger mean? – Stronger would mean that it can handle a higher output power.
Okay, but what parameters are we considering?
And it’s crucial whether our consumer requires current-regulated or voltage-regulated power supply.
LED strip room lighting – fantasy
Voltage-regulated power supplies
The common understanding generally revolves around fixed voltage power supplies, even though the term voltage-regulated might be more accurate, but many people have never heard this expression. Examples include a 5 Volt, 12 Volt, or 24 Volt adapter, or even a laptop charger. If it is 12 Volts, then it always has a 12 Volt output, and if, for example, it is 60 Watts, that is, 60 Volt-Amperes, it can be loaded up to 60 Watts, meaning the output current depends on the power of the connected consumer. In this case, the output current can be between 0 and 5 Amps. If we connect a 30 Watt consumer, the output current will be 2.5 Amps.
Power supplies providing higher output current
If in the case of such a voltage-regulated power supply, a stronger supply means choosing one with higher Amperes, i.e., instead of a 5 Amp 60 Watt supply, we choose a 6 Amp 72 Watt, or even a 10 Amp 120 Watt supply – there is no obstacle, we are making a good decision. In this regard, we need to consider two things:
- Some power supplies are designed, as stated by the manufacturer, to operate at a maximum load of 80% continuously, while others can operate at 100% load continuously. If the manufacturer does not provide such information, we must assume that it can only operate continuously at a maximum load of 80%. So, from a physical standpoint, we do not cause any harm by choosing a power supply with a higher Amperage. However, a higher power supply is more expensive, so we might easily make the mistake of unnecessarily purchasing a more expensive power supply.
- The other mistake is that our consumption may increase. Here, we are not talking about a significant increase in consumption, but rather that the efficiency of a power supply can be lower the smaller its load is. Naturally, the more reliable the quality of the power supply we choose, the smaller this effect will be. If we operate a 40 Watt consumer with a 60 Watt power supply – it is possible that the total consumption will be 46 Watts, but if we operate it with a 100 Watt power supply, then it will be 50 Watts. (These are just example numbers.) Our consumer will still consume 40 Watts, so if it is a LED strip, it will light up the same in both cases, but while operating with a 60 Watt adapter, the adapter’s own consumption will be 6 Watts, and with a 100 Watt adapter, it will be 10 Watts. And this is not necessarily because the efficiency of the 100 Watt power supply is worse (let’s assume that the technical construction is the same), but simply because the 60 Watt power supply is operating at 66%, while the 100 Watt power supply is only operating at 40%. Of course, we can say that what difference does the 4 Watt difference make – this is true, but now we can better understand why there are so many performance sizes.
So an oversized power supply is not only more expensive to purchase but can also consume more power continuously. One might say, this is true, but at least it heats up less. Okay, but let’s also consider that a careful manufacturer has taken the heating factor into account during design.
Since we are talking about higher current power supplies, it’s worth mentioning what happens if we use a power supply with lower current than necessary?
Generally, today’s power supplies are equipped with overcurrent protection. This value can vary by type, sometimes it’s 10-20%, and in some cases, it can be as much as 50%. This means that there are some 60 Watt (5 Ampere) power supplies that can still operate under a 90 Watt load, meaning 7.5 Amperes of current, and the overcurrent protection does not shut it down. This absolutely does not mean that we can safely overload power supplies continuously. This will undoubtedly lead to premature failure. Moreover, power supplies are also equipped with over-temperature protection. So, even if the overcurrent protection does not shut it down, the over-temperature protection will. Who would want to operate a device that keeps turning itself on and off? Additionally, even if we operate it in an overloaded state and it seems to ‘handle it well’ – the product will definitely have a shorter lifespan. Do not abuse the fact that power supplies can operate above their rated maximum load!
Power supplies providing higher voltage
Now, this is a dead idea. It’s not the power supply that will fail first, but the connected consumer. If you run a 12 Volt LED strip with a 24 Volt power supply, you might enjoy the bright light for a short while – “wow, it’s shining so brightly!” – then suddenly, the whole thing will burn out. The LED strip will draw the same current, but with twice the voltage, the consumption will be doubled. The result is double heat production, and if it wasn’t designed for that, it won’t be able to handle the heat. A short circuit might also occur, which means even more current. Sure, you could say that a modern power supply also has short-circuit protection, but even if the power supply survives, we still lose our consumer. It’s even more foolish to think that if you have a 60 Watt LED strip (and it’s 12 Volts), you can buy a 24 Volt adapter that is also 60 Watts. This is the doubly dead idea. This 60 Watt LED strip will draw 5 Amperes of current, whether it receives 12 Volts or 24 Volts. But if it receives 24 Volts, its consumption will immediately become 120 Watts instead of 60 Watts – and it’s definitely not designed for that. Moreover, our 60 Watt 24 Volt power supply can only deliver 2.5 Amperes, so at a 5 Ampere current demand, the overcurrent protection will definitely shut down the electronics. And then we can be thankful that our LED strip didn’t burn out.
Since we’ve discussed LEDs and the aforementioned lower current power supply, it’s worth considering what happens if we want to operate a consumer with a lower voltage power supply.
Sticking with the LED strip example, a 24 Volt LED strip won’t light up with 12 Volts, perhaps the red will if it’s an RGB strip. Similarly, a 12 Volt strip won’t work with 5 Volts. In some constructions, there might be a faint light. Those who attempt such experiments usually say they expected that the 24 Volt strip wouldn’t shine as brightly with 12 Volts, but they would have expected at least half the brightness. Well, no, diodes have a forward voltage threshold (a LED is also a diode), and below that, it won’t work at all, not even a little bit. So it strongly depends on the construction how much it will light up – generally, not at all, because in general, you can say that the forward voltage of LEDs is around 2/3 of their operating voltage. Conversely, they are typically operated at about 1.5 times their forward voltage. Of course, this isn’t always the case, but it might apply to LED strips. Clearly, a high-power, large heatsinked LED can be overdriven more, but you won’t be buying such power supplies for those. In the case of RGB strips, you might find that the red still lights up because it is slightly overdriven compared to the green and blue LEDs to ensure the light output is close to the other two colors since red LEDs have poorer efficiency.
Current-regulated power supplies
If you haven’t dealt with electrical things before, but you know that there are different power supplies that provide various voltages and deliver just as much current as the connected device requires, and it’s enough to know that the power supply should be capable of delivering at least as much power as the device needs – and everyone will be happy. Now, you might just learn from me that there are power supplies with a completely opposite logic, and if you understand the essence of it – it might make your brain spin for a moment. But don’t worry! At least if your LED panel’s power supply fails, you won’t be left wondering what voltage power supply to buy, because you’ll be puzzled when you see that the faulty power supply’s output ranges from 42 to 50 Volts. What? – They can’t even decide how much!
So, the essence of a current-regulated power supply (more elegantly called a LED driver in the case of LEDs) is that the output current does not change. For example, it could be 350mA, or perhaps 950mA. This is just like the voltage-regulated power supplies detailed above, where the 12 Volt always remains 12, the 24 Volt always remains 24, and the current adapts to the power requirements of the load. In the case of a current-regulated power supply, the current level does not change, and the voltage adjusts to the load’s power requirements. This solution requires more careful application. While voltage-regulated power supplies usually do not have a defined minimum current draw requirement below which they won’t operate, meaning that a 5 Amp voltage-regulated power supply can be connected to any load drawing between 0 and 5 Amps as long as the voltage matches. In the case of current-regulated power supplies, there is always a lower and an upper limit for the output voltage. For example, if a 950mA LED driver indicates 42-50 Volts, it means it will not deliver a voltage higher than 50 Volts or lower than 42 Volts. In other words, you can connect a load with a power rating between 39.9 and 47.5 Watts to it, provided the load requires a 950mA current-regulated drive. If you have a 45 Watt LED panel that is 950mA current-regulated, then 45/0.95 = 47 Volts is its voltage requirement. So, the right choice when buying a new current-regulated power supply for your old LED lamp is to ensure that the voltage range on the power supply includes 47.36 Volts and, of course, has a 950mA current drive. Any other solution is wrong.
Power supply providing higher current:
It causes unstable operation because the power supply’s output current does not adjust to the lower current requirement of the light source, leading to voltage fluctuations or ripple. This can disrupt the operation of the load. Heat generation increases because the power supply continues to generate maximum current, wasting unnecessary energy. If the power supply delivers too much current, the current flowing through the LEDs exceeds the saturation current. This increased current leads to overheating in the LEDs. Overheating damages the LEDs’ structure, shortening their lifespan, and can lead to their eventual failure.
Additionally, if the current exceeds the saturation current, the voltage demand can become so high that the power supply cannot handle it, resulting in a shutdown due to overload in the best case. However, if it stays below the limit, continuous higher power can damage the power supply’s components.
Let’s also mention when you try to use a current-regulated power supply that provides less current than intended. You will cause an overcurrent in the power supply since the LED light source’s demand exceeds the supply’s current limit. This leads to overheating, damage to the power supply, and even the destruction of the load. The LEDs will not receive enough current, which increases the voltage across the LEDs as they try to maintain power. But this voltage increase will compensate for the drop in current.
Even if the power output remains the same, if the voltage increases, the heating will intensify instead of the luminous flux, due to the non-linear voltage-current characteristic inherent to diodes, including LEDs. This leads to reduced brightness of the LEDs with overheating, which shortens their lifespan and can lead to their eventual failure.
Power supply providing higher voltage:
LED panels driven by a current-regulated power supply are designed for specific voltage ranges. If the power supply provides too high a voltage, the LEDs will not turn on. In some cases, the LEDs may flicker or emit a weak light before they fail. If the power supply provides only slightly higher voltage than the LED panel requires, the LEDs may receive too much energy, leading to overheating. As the voltage increases, the current increases more slowly (non-linear voltage-current characteristic), and at some point, it reaches saturation. At that point, the current will no longer increase with the excessively high voltage. The LEDs will receive too much energy, which can cause overheating. Overheating can reduce the brightness of the LEDs and shorten their lifespan.
Current-regulated power supply is sensitive to changes in the load’s current and voltage requirements. Demand exceeding the power supply’s maximum output can lead to overload, damage, and instability, while lower demand than the power supply’s capacity can cause operational issues and reduced efficiency. Proper operation and the avoidance of damage can only be ensured by matching the power supply and the load.
This article was born because one of my customers thought it natural to buy a 950mA current-regulated power supply that operates in the 42 to 50 Volt voltage range. Unaware of the essence of current-regulated drives, he intended it as a replacement for his failed LED panel power supply.
However, the LED panel was designed for 600mA drive. He knew it was 36 Watts, which clearly implies that the panel has a 60 Volt voltage requirement. He expected that since this power supply only provides 50 Volts, there would be no problem if it didn’t shine as brightly since the voltage is 17% lower, and this reduced brightness would be sufficient.
Fortunately, the power supply did not turn on at all, so the LED panel was spared from being destroyed by 58% higher Amperage. The likely reason is not only that the power supply would have needed 17% more voltage than its operating range, but also that due to the non-linear voltage-current characteristic of LEDs, the LED would have already entered a saturation range at that current, significantly exceeding the designed 60 Volt operating voltage. Thus, the LED panel was luckily saved from destruction.