7 x 120mm PC Fan (No LED) + 1 x LED Strip (Flashing) = 12V DC / 3.0 A Power Supply

[ScyberMhaster]

Good day!

The reason why I never attached the fans and LED strip to my computer's power supply, is that my UPS can't stand / hold the power draw and overloads when there are electricity cuts (720VA / 430W). So, I managed to make an alternative power source, however, I only have a 12V DC / 3.0 A Power Supply from my dead monitor. I cut the wires and managed to solder it up to the + and - of the fans and LED strip, in series. As I turn in on, yes the fans spinning, but the LED strip is not blinking or flashing, it is just steady. Am I lacking AMP on this load or voltage drop? Does the power supply can't provide adequate power to the fans and LED strip?

 

[dave9]

What do you mean by "in series"? Consider each fan one component and the LED strip the other component. Each component should be in parallel with the other components, nothing should be in series except the LEDs on the strip in series with other LEDs, if/as already manufactured for 12V operation.

Can you link to this LED strip? What is its current consumption rating? Can you do the same for the fans? We must know the current requirements of each in order to know if they are within the capability of the 3A PSU, but frankly if you run these continuously it is better to have a PSU with ample margin over the load it is powering, to promote long lifespan.

You should be able to use a multimeter to measure the power and ground connected to the LED strip and see if it is near 12V.

 

[KJ6EAD]

When calculating energy budgets, a mistake I often see people make is using the device maximum current rating from a label or manual instead of measuring actual current draw under typical conditions.

 

[ScyberMhaster]

What do you mean by "in series"? Consider each fan one component and the LED strip the other component. Each component should be in parallel with the other components, nothing should be in series except the LEDs on the strip in series with other LEDs, if/as already manufactured for 12V operation.

Can you link to this LED strip? What is its current consumption rating? Can you do the same for the fans? We must know the current requirements of each in order to know if they are within the capability of the 3A PSU, but frankly if you run these continuously it is better to have a PSU with ample margin over the load it is powering, to promote long lifespan.

You should be able to use a multimeter to measure the power and ground connected to the LED strip and see if it is near 12V.

My bad, yes, its parallel, kinda confused on that setup. Well, frankly, the fans and the LED strip do not have any indicators of wattage / amps. I just assume that it needs 12V DC, based on my experience.

 

[ScyberMhaster]

When calculating energy budgets, a mistake I often see people make is using the device maximum current rating from a label or manual instead of measuring actual current draw under typical conditions.

Well, I do not have any budget on purchasing high-end power supply to power these cheap stuff, that is why I use whats on my current resources.

 

[ScyberMhaster]

What do you mean by "in series"? Consider each fan one component and the LED strip the other component. Each component should be in parallel with the other components, nothing should be in series except the LEDs on the strip in series with other LEDs, if/as already manufactured for 12V operation.

Can you link to this LED strip? What is its current consumption rating? Can you do the same for the fans? We must know the current requirements of each in order to know if they are within the capability of the 3A PSU, but frankly if you run these continuously it is better to have a PSU with ample margin over the load it is powering, to promote long lifespan.

You should be able to use a multimeter to measure the power and ground connected to the LED strip and see if it is near 12V.

If ever that it cannot reach the required 12V (LED Strip / Fans), will it decrease the lifespan?

 

[dave9]

My bad, yes, its parallel, kinda confused on that setup. Well, frankly, the fans and the LED strip do not have any indicators of wattage / amps. I just assume that it needs 12V DC, based on my experience.

Try powering only one fan and measuring current consumption, then repeat measuring only the LED strip. Next calculate what the sum current of all things powered simultaneously would be. Next you can progressively add more things in parallel to see if the PSU can maintain high enough voltage.

Yes, overloading the PSU can decrease its lifespan, but without data, we can't know if there is an overload. It would be easy to pick 7 fans and an LED strip that consumes less than 3A, yet it would also be easy to pick combinations that do exceed 3A.

We don't even know if your dead monitor was due to a failure within it or if it appeared dead because the power supply failed. Having repaired several monitors myself, one of the most common failure modes is that the capacitors in the power supply fail. Repairing the power supply with new capacitors is all that was needed to fix the monitor in such cases.

 

[KJ6EAD]

Well, I do not have any budget on purchasing high-end power supply to power these cheap stuff, that is why I use whats on my current resources.

An energy budget has nothing to do with money. It's about matching the wattage requirements of all loads to the power supply capacity.