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I've asked a similar question a few months ago, but I have a few more questions.

Background: I plan to chain multiple LED strips to one another (by soldering) to make one, long LED strip that will be hung up along the outline of my room. I do not currently know whether four LED strips will be enough to surround the entire room, but I purchased five just in case.

LED Strip

Power Supply - Not the exact item, but an identical one rated for 12 V and 25 A.

As you can see, the LED strip is rated at 12 V DC, and consumes 48 W per strip.

I had the opportunity to measure the current drawn from one strip at 12 V, and it reached almost 1 A.

Question: If I were to chain four or five of these strips together, would they be able to handle the amount of current drawn at 12 V? If not, would connecting wires to ground at each chain prevent too much current being drawn?

Note: I plan to supply each side of the long chain (four or five strips) with 12 V and not just one end.

Thank you!

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  • \$\begingroup\$ The LEDs on the middle are definitively going to see a lower voltage. I doubt the strip is going to overheat, but the middle ones will be dimmer than the ones closer to the power input. That said, it sometimes it's not perceptible. There is no way to tell without knowing a bunch of info (such as strip resistance per meter), so it's way easier to just test it out and see if its acceptable. \$\endgroup\$
    – Wesley Lee
    Jul 1, 2017 at 18:24
  • \$\begingroup\$ @WesleyLee I will connect more power lines to the middle strips if needed, but I just want to make sure that the whole strip won't burn out if it ends up drawing close to 5 A. \$\endgroup\$
    – Jacob G.
    Jul 1, 2017 at 18:26
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    \$\begingroup\$ There's something wrong between the specifications and your measurements. From \$ P = VI \$ you can calculate the expected current as \$ I = \frac {P}{V} = \frac {48}{12} = 4 \; A \$. You only measured 1 A. \$\endgroup\$
    – Transistor
    Jul 1, 2017 at 18:27
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    \$\begingroup\$ In my experience it just won't reach high currents simply because the voltage drop will make the LEDs draw less and less current. You should be safe to test and check periodically. \$\endgroup\$
    – Wesley Lee
    Jul 1, 2017 at 18:28
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    \$\begingroup\$ The "drawn" current is less than the advertised one because the advertised current does not take into account the resistance of the strip or the wire. \$\endgroup\$
    – Wesley Lee
    Jul 1, 2017 at 18:28

1 Answer 1

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Question: If I were to chain four or five of these strips together, would they be able to handle the amount of current drawn at 12 V? If not, would connecting wires to ground at each chain prevent too much current being drawn?

The issue will be the voltage drop along each strip. Too many strips and the next strip will be dimmer till it makes no sense any more. Powering from both ends will help, but if need be you will need to run extra wires to both the ground and the power side at some intermediate point.

BTW: You can calculate the power lost to wire heating in each segment by the following formula.

\$(I_{out} + (I_{in} - I_{out})/2) * V_{Drop}\$

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  • \$\begingroup\$ So I assume that not enough current will be drawn to burn out the LEDs? \$\endgroup\$
    – Jacob G.
    Jul 1, 2017 at 18:59
  • \$\begingroup\$ @JacobG. It wont burn out the leds... but the power/ground trace can if it's too high a drop. They are usually rated for max in series. \$\endgroup\$
    – Trevor_G
    Jul 1, 2017 at 19:01

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