I have two led strips used for 2x27" monitor bias lighting. Each have their own USB cables for power. These two USB cables are plugged into a 2-port wall charger for a phone. I would like to use a 2x female to 1x male adapter to join the two USB cables into one, then plug it into a much smaller 1-port USB wall charger. The reason is due to my space constraints.

Will doing this impact its energy efficiency, ie using an adapter like this?

https://www.aliexpress.com/item/1005004340044483.html

  • UnlimitedRumination [he/him]@sh.itjust.worksEnglish
    1·
    8 months ago

    Watts in a resistive example like yours is Volts x Amps. I would have been able to much better answer this question a year ago so forgive me if I’m misremembering the specs but I’ll answer since nobody else has. Two things that suggest to me this might be a bad idea:

    • Charger is 40W, that’s probably usb PD (I don’t know anything about QC so maybe I’m wrong). PD supplies more than 15W (5V x 3A) by stepping up the voltage, not the amperage. While stepping up either would likely be bad or very bad for some part of your circuit, don’t worry about that though; without the powered device telling it to, PD won’t activate. It should max out at 15W… I think. It depends on the resistance on the CC lines and using a splitter could screw up the resistance that tells the power supply which USB version to support so it can go up to 3A (15W). Sorry, it’s been a while since I’ve worked with USB power. 2 strips of 11W will need more power than that. Basically my concern is you won’t get adequate power out of the charger for one reason or another.
    • Where are you getting the 11.52W/min number? Watts don’t have a time unit and that much precision sketches me out. Almost as if someone who isn’t adequately educated measured the power straight off a multimeter once and just wrote that on a product page. Is the LED strip from a reputable manufacturer?
    • ChaoticNeutralCzech@feddit.deEnglish
      1·
      8 months ago

      He meant watts per meter, not minute – the strips can be cut and rejoined. As for the 5 Ah, no clue.

      The circumference of a monitor is more than 1 m, so a charger of 3 A at least will be necessary for each. This is why I prefer higher-voltage strips where less current is required and higher resistance is tolerable. Anyway, the power is quite high and this could cause overheating problems.