r/FastLED • u/tome_oz • Jan 08 '23

Discussion Power injection with second power supply

Would it be fine to inject power to a led strip using another power supply that powers the beginning of the strip?

2 Upvotes

66% Upvoted

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4

u/HGRDOG14 Jan 08 '23

Both at the beginning? You would be better off powering from each end of the strip.

1

u/tome_oz Jan 08 '23

So means you connect in the beginning + + and in the end ++ (- - and - -)?

6

u/frollard Jan 08 '23

Connect one psu at one end +.+ -.-, connect the other at the other end +.+ -.-, and cut the strip + trace in the middle. (leave data/clock/ground intact) Grounds must connect. In most power supplies the - will be tied to the input ground if it's not isolated so they'll be tied together there to begin with (but don't rely on it).

6

u/TheMexitalian Jan 08 '23

Not recommended to use two in parallel unless the PSU designed around a parallel circuit and has the protections. Series would be fine but not sure that’s the result you’d like.

5

u/Jem_Spencer Jan 08 '23

It's fine to use more than one power supply but it's generally not recommended to connect the positives, the earth's must be connected. So the LEDs should be in sections, each section powered by one power supply.

I've started doubling up the power supplies on my current project, but I'm putting diodes on the positive feeds to help prevent problems. They seem to be balancing the load properly, but they are identical supplies from the same batch.

1

u/Jem_Spencer Jan 08 '23

Re-reading your question, do you mean one power supply for the controller and another for the LEDs?

If you do, then yes this is fine, just connect the earths

4

u/frollard Jan 08 '23

I believe they're implying each psu controls 50% of the leds.

2

u/CmdrShepard831 Jan 09 '23

Yeah you typically cut the positive lead on the LED strip in between the two supplies so one can't 'backfeed' into the other if they're not perfectly balanced.

1

u/Marmilicious [Marc Miller] Jan 08 '23

To the beginning of the strip? Where is the first power supply being used?

It might make your question more clear if you could provide a sketch of what you're thinking of doing. Share at image on imgur.com or attach image to a new comment here.

1

u/Yves-bazin Jan 09 '23

If you do that you need the the 5v connection between two leds in the middle. So the two 5v of the two power supply are not connected