48 VDC to 5 VDC with converters and quicksplicers?

Discussion in 'Power Supplies' started by ThisPlay, Aug 9, 2017.

  1. ThisPlay

    ThisPlay New Elf

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    hi all,

    I plan to run a 48V line from my meanwell HEP-320-48A along my 30m 5V led stripe and I do power injection every 2m. (it needs to be 2m) I want to use DCDC converters to get the voltage down to 5V. 2m of my stripe need 36W and 7,1A.

    I found cheap converters on alibaba: 48 VDC to 5 VDC max 10A. Is 74% power draw enough to have these converters working within their specifications? They have no spec sheets on their site, I will have them send me one.

    In total I have to do 100m+, so my plan was to use T-Tap quick splicers to tap into my 48V line, go through the DC DC converter, and then power inject into the stripe. Would you recommend them or instead use a more conventional connection? will they even add to the total resistance of the powerline?

    All those connections will be put inside a electrical box. (Aufputzbox), since the installation is going to be setup permanently in an industrial production line. I plan to use shielded cables for the connections between the stripes.
    (I have max. 16meters led with max 15m connection in between) Of course I will be running a test setup along the planned lines before install.

    Any thoughts on that?

    Regards, Achim
     
  2. diyer

    diyer Full Time Elf Generous Elf

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    Hi Achim
    I'm just trying to fathom your logic here, a Meanwell HEP-320-48A is 48volt 320W = 6.7 amps maximum output. Why wouldn't you you use a higher wattage 5V supply?
     
    Last edited: Aug 9, 2017
  3. David_AVD

    David_AVD Good news, everyone!

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    He's trying to minimise the losses in the cabling. Higher voltage (on the feeder cable) = less current (for the same wattage) hence less voltage drop.
     
  4. videoman3857

    videoman3857 Full Time Elf

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    48 - 5 volt will generate a fair bit of heat at each buck converter. Make sure they are well ventilated
     
  5. David_AVD

    David_AVD Good news, everyone!

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    Maybe you're thinking of a linear regulator? The losses (and heat) with those can be huge.

    The losses in a reasonable buck converter are pretty low. How much exactly depends on the output wattage and the conversion efficiency.

    The efficiency can change a little with input-output differential, but also with load and other factors.
     
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  6. OP
    OP
    ThisPlay

    ThisPlay New Elf

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    1.png 542.jpg
    I ordered two of these for testing purposes. they will be mounted on the outside of the junciton box.
    72% load seems reasonable (2m ledstripe need 7.2A) - maybe they will work within their specifications?

    Any thoughts on the quick splicers? Yes / No?
    100pcs-Blue-T-Tap-Insulated-Quick-font-b-Splice-b-font-Wire-font-b-Terminal-b.jpg
     
  7. David_AVD

    David_AVD Good news, everyone!

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    You can use the DC-DC converter at a lower than their rated current with no issues.

    I've not used those splices, but the 48V side of the converter will be drawing less than 1 Amp so they should be fine.
     
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  8. videoman3857

    videoman3857 Full Time Elf

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    No idea about using these with your lights. May depend on the current draw. Not too sure how much contact they have with the wire supplying the power.
    On a different note, our work refrigeration mechanic used these so he could "tap" into a power supply that had little slack and room to get to.
    In theory all would work fine. In practice, the push on wire terminal, over time ,would come adrift from the connector. This I believe was from the bouncing and movement of the vehicle. A slight modification to the terminal fixed the issue.
    I think the only way you will find out is to experiment and learn like the rest of us. - or stumble across someone who already has.
     
  9. videoman3857

    videoman3857 Full Time Elf

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    Learning every day David, learning every day.
    I haven't seen the converters pictured. The specs listed are pretty impressive to some one like me - (still learning)
    The casing design has heat dissipating fins on it. Which is good. The faster the heat - no matter how much or little, is removed from the electronics the better.
     
  10. multicast

    multicast Senior Elf Generous Elf

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    To a point.. Most *should* work pretty much ok across their full range. ( for any resonable design ).. There are some DC/DC converter that wont' work well across a variable load.. This is sometimes done with things that present constant loads.. Sequenced LED's hardly are constant. A 70% load seems resonable, but remember thats the 'full' load.. not a 'constant' load.

    Without knowing exactly what these are, i'd suggest that you get one try it and and check, before you commit to buying a stack of them.
     

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