Can someone help with Amp Load?

mnm99 · Jan 21, 2015

I thought I figured it out, but something doesn't make sense to me. What would be the load on the + lead set up with the following?

12.7V
25 feet of 22ga wire
.700ma each LED
24 leds, 3 in a string , parallel

I was getting 9.6v on the positive lead with a 3.6 Amp draw. Does that make sense? I know the voltage drop looks correct with that amp draw, but I thought I would get more of a draw. Do I check the + and - and add them up for the draw? Thanks

+ -
0-0-0
0-0-0
0-0-0
0-0-0
0-0-0
0-0-0
0-0-0
0-0-0

mercrazy · Jan 21, 2015

what kind of current control and power source?

Genes · Jan 21, 2015

If you are reading 9.6 volts, then the supply is not 12.7 volts; at least not under load. No, you do not sum the current measurements in the + and- leads, they should be exactly the same reading as it is exactly the same current. If you only have 9.6 volts under load then the voltage across each led is 3.2 volts. So the current may be much lower (not 700 ma ) depending on the type of led and the total current may only be 3.6 amps. You need to make sure your power source can supply 12.7 volts at around 6 amps. The 22 gauge wire is very small and the 25 feet contributes about .25 ohms to the system. So you are losing about 1 volt in the 25 feet of wire.

mnm99 · Jan 21, 2015

Genes said:
If you are reading 9.6 volts, then the supply is not 12.7 volts; at least not under load. No, you do not sum the current measurements in the + and- leads, they should be exactly the same reading as it is exactly the same current. If you only have 9.6 volts under load then the voltage across each led is 3.2 volts. So the current may be much lower (not 700 ma ) depending on the type of led and the total current may only be 3.6 amps. You need to make sure your power source can supply 12.7 volts at around 6 amps. The 22 gauge wire is very small and the 25 feet contributes about .25 ohms to the system. So you are losing about 1 volt in the 25 feet of wire.

I am seeing 9.7-10v on the lead at the LED with 12.7v coming off my car battery. The wire is 22ga twisted pair. The loss in voltage with the amp draw are correct per the calculator. I just though I should have more of a draw than 3.6A.

http://www.calculator.net/voltage-drop-calculator.html Put in the specs

Can someone help with Amp Load?

mnm99

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mercrazy

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Genes

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mnm99

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