Power usage of LED light using AC adapter

In summary: LED light to use an AC-DC adapter to power it instead of 3 AAA alkaline batteries. The adapter gets moderately warm after running for a while. The LED does not put out as much light as the 25-watt R14 miniflood light that he was using, but it's enough to illuminate a computer keyboard in a semi-dark room.
  • #1
daddybruce56
1
0
I have a question about how much power I’m using to run a LED light that I modified to
run off an AC-DC adapter instead of 3 AAA alkaline batteries. The light is a Sylvania Lighting Dot It Black Led Swivel, which uses about 1/4 of a watt (4.5 V X 54.7mA) on batteries. The light would dim unacceptably after about 20 hours of use. So as to not burn through lots of batteries I did this modification (I know I could have purchased rechargeable batteries but since I hang on to old AC-DC adapters for this very reason, it was a no cost project. It works great – always max brightness.

Here are the specs on the adapter:

INPUT: AC 120V 60HZ 8W
OUTPUT: DC 4.5V 600mA
Class 2 Power Supply for use with audio products without antenna connections. Masugarbagea Electric CO. LTD. Made in China. It has a polarized two-prong plug. I have no idea how old it is, what it was originally used for or, what the exactly is the internal circuitry. It gets moderately warm after running a while with nothing connected.

Measured 6.1VDC unloaded output of the adapter (Measured same with adapter connected to light – LED OFF, at the battery terminals where adapter wires are soldered. Measured 5.25V DC at terminals with light ON. I also measured the current -- about 55mA DC approximately the same as the battery amount above, which comes from www.ledmuseum.org’s[/URL] review of the “puck”, style Dot-It.

Is the 8W AC standby or max? (Is that the power it uses just plugged in with no load or what it uses with the DC load drawing the full 600mA?) Can I take the actual DC load (55mA) divided by the max DC load (600mA) and multiply that by 8W to get .73W that gives me ~=1W used total? Am I assuming anything that is wrong? Also, is the 5.25V DC a problem?

Any way it comes out it is still less power than the 25-watt R14 miniflood light I was using. The LED does not put out as much light as the miniflood but it‘s enough to illuminate a computer keyboard in semi-dark room, which is what I wanted.

Thanks, daddybruce56
 
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  • #2
The 8W is the total input power when it is putting out the rated load (2.7W). The VA (volt-amps) will be more.

Bob S
 

Related to Power usage of LED light using AC adapter

1. How does the power usage of LED lights compare to traditional incandescent lights?

LED lights use significantly less power than traditional incandescent lights. On average, LED lights use 75-80% less energy than incandescent lights, making them a more energy-efficient choice.

2. Does the power usage of LED lights vary depending on the color or brightness?

Yes, the power usage of LED lights can vary depending on the color and brightness. Generally, brighter and cooler-colored LED lights will use more power than dimmer and warmer-colored LED lights.

3. Can LED lights be used with any type of AC adapter?

No, LED lights require a specific type of AC adapter that is compatible with their low voltage and constant current needs. Using the wrong AC adapter can cause damage to the LED lights or decrease their lifespan.

4. How do I calculate the power usage of LED lights with an AC adapter?

To calculate the power usage of LED lights, you will need to know the wattage of the LED lights and the voltage and current output of the AC adapter. Multiply the voltage and current to get the wattage, and then compare it to the wattage of the LED lights to determine the power usage.

5. Can using an AC adapter with LED lights save me money on my electricity bill?

Yes, using LED lights with an AC adapter can save you money on your electricity bill. As mentioned earlier, LED lights are more energy-efficient and use less power than traditional incandescent lights, resulting in lower electricity costs over time.

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