Does anyone know about LED strip and amp draw?
I have a 5m strip and it says it draws about 900mA per meter. So for a 5m strip it should draw about 5A at 12v.
I've put it onto 12v and it only draws .8A
Am I measuring it wrong?
See photo:
Put meter in series with the positive wire. Which I have done countless times with other things. I'm just confused it saying about 5A when it draws .8A
Cheers
I have a 5m strip and it says it draws about 900mA per meter. So for a 5m strip it should draw about 5A at 12v.
I've put it onto 12v and it only draws .8A
Am I measuring it wrong?
See photo:
Put meter in series with the positive wire. Which I have done countless times with other things. I'm just confused it saying about 5A when it draws .8A
Cheers
Attachments
Maybe it is a good tip not to use them while being wound. They overheat quite fast that way. I think the specs are wrong. 5A so 60W of LED light seems an awful lot to me! Not being struck by any knowledge regarding these cheap devices I would assume the current should be 900 mA per 1, 2 or even 5 meters....
* with (erroneous) assumption of 5A that wound up bunch of LEDs would melt in very short time....
* with (erroneous) assumption of 5A that wound up bunch of LEDs would melt in very short time....
Last edited:
Well it says 60 LEDs per meter at 5 meters that's 300 LEDs.
5A divided by 300 LEDs is 16.66ma per LED, which seems reasonable.
800ma divided by 300 LEDs is 2.66ma per LED, which seems too low.
Something seems wrong.
If they are wired in groups of 3 LEDs in series then you would have
800ma divided by 100 groups of 3 LEDs for 8ma per LED, possible.
Bob
5A divided by 300 LEDs is 16.66ma per LED, which seems reasonable.
800ma divided by 300 LEDs is 2.66ma per LED, which seems too low.
Something seems wrong.
If they are wired in groups of 3 LEDs in series then you would have
800ma divided by 100 groups of 3 LEDs for 8ma per LED, possible.
Bob
I did notice on the package that it says it produces 20 to 40% less brightness than their
high output version using the same LEDs. This could be the difference between the 5A and
800ma.
The 5050smd LED package is rated at 3.4V 60ma max, If they did them three in series and
the 5M string drew 5A then the current in each LED would be 5A/100(3 LEDs in series)= 50 ma.
They would run hot with so little heat sinking.
high output version using the same LEDs. This could be the difference between the 5A and
800ma.
The 5050smd LED package is rated at 3.4V 60ma max, If they did them three in series and
the 5M string drew 5A then the current in each LED would be 5A/100(3 LEDs in series)= 50 ma.
They would run hot with so little heat sinking.
Last edited:
Most led strips have a common anode, and the colours are driven from the three cathodes (sinking).
Maybe your only measuring one of the three channels.
As Jean-Paul noticed rightfully already in #3: measure and lighten up unwound only!
Maybe your only measuring one of the three channels.
As Jean-Paul noticed rightfully already in #3: measure and lighten up unwound only!
Measuring diodes is different than measuring a straight load. With an ordinary diode, current flows in one direction. With LEDs, you're actually running the diodes backwards. When the current becomes too much for the diode to resist, it goes into breakdown. Then the LEDs emit light. So, one side of the supply is going different than the other as far as Amps are concerned, unless you use a good meter that samples.
And, LEDs actually pulse. LED power supplies are current limiting devices, which adds to the confusion. But if you just measure both sides of the supply in both directions, one of those four configurations will be correct. But that's only if you use a good meter that recognizes the signal. A good rule of thumb is for a given light output per watt, LEDs are 25x of incandescent.
With authentically spec'ed LEDs, 300mW is just blasting bright. I have a 200W LED light for photography. It has 2 arrays of 16x16 LEDs, but the arrays are only about 1 sq, in. ea.. It is so bright, if you use it up close, the camera doesn't know what to make of it, and so puts a colored cast over the frame. If you looked straight into it, you'd bee blind for an hour! I aim it up at the corner of the ceiling, and use the reflected light. One time I was using it in the living room at 2am, and someone called the cops to report alien activity at my house!
They actually investigated by knocking on my door, and asking me what I was doing!
And, LEDs actually pulse. LED power supplies are current limiting devices, which adds to the confusion. But if you just measure both sides of the supply in both directions, one of those four configurations will be correct. But that's only if you use a good meter that recognizes the signal. A good rule of thumb is for a given light output per watt, LEDs are 25x of incandescent.
With authentically spec'ed LEDs, 300mW is just blasting bright. I have a 200W LED light for photography. It has 2 arrays of 16x16 LEDs, but the arrays are only about 1 sq, in. ea.. It is so bright, if you use it up close, the camera doesn't know what to make of it, and so puts a colored cast over the frame. If you looked straight into it, you'd bee blind for an hour! I aim it up at the corner of the ceiling, and use the reflected light. One time I was using it in the living room at 2am, and someone called the cops to report alien activity at my house!
They actually investigated by knocking on my door, and asking me what I was doing!
Well, this is absolutely new for me. Are you sure to not confuse with zeners?
Best regards!
Cheap LED strips - they use inline resistors for current control as opposed to higher end lighting which will use active CC drivers. If you wire the strips in parallel the currents should add as expected (as long as your power supply supports that current output, of course).
Hal
Hal
You can put meter on ohms setting and touch the leads of one LED. The higher resistance direction will faintly light the LED. The other direction won't.
It surely won't, at least not with a single LED. With the red (positive) probe at the anode and the black one at the cathode, the LED will light and the meter shows a resistance in the hundreds of ohms (depending on the LED) range or the knee voltage when in diode check mode. With the probes reversed, an infinite resistance will be displayed and the LED remains dim.
LED arrays, for example LED strips, may behave somewhat different when probing a single LED without having it disconnected.
Best regards!
LED arrays, for example LED strips, may behave somewhat different when probing a single LED without having it disconnected.
Best regards!