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parallel led array

Discussion in 'LEDs and Optoelectronics' started by lightman, Nov 6, 2015.

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  1. lightman

    lightman

    57
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    Nov 6, 2015
    hi fellas this is my first post i am wishing to build an IR Illuminator for ghost hunting i want to make it from 3 5w high power ir led and wire it in a parallel led array so each led gets same power i worked out if i run them of a 3.7 volt battery i would need to add a 2.7 ohm resistor to each led so not to over power the led thing is i am only getting around one and half hours continuous use so what would i need to do to run same set up of two 3.7 battery's any help please fellas ?
     
  2. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Sounds like you know what you are doing... you scared me when you said parallel LEDs, but you are actually using a resistor on each one. Thanks! That gets missed by a LOT of people.
    As far as running with two batteries, simply connect the two batteries in parallel and your light should last twice as long!

    *Special Note : When you connect two unbalanced batteries in Parallel, you run the risk of causing current to flow between batteries. Never connect a fully charged battery in parallel with a used battery!
    The battery with the higher voltage will actually cause current to flow backwards through the battery with a lower voltage. So either connect them when they are both freshly charged, or when they are dead. You can always use a multi-meter to confirm the voltage is the same prior to connecting them.
     
  3. lightman

    lightman

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    Nov 6, 2015
    hi thank you for your help the new battery holder olds two battery's not sure I understand wire the two battery's in parallel do you have a pic sorry for being so dum
     
  4. lightman

    lightman

    57
    1
    Nov 6, 2015
    its ok I see what you mean two single battery holders + soldered + - soldered to - with just a single wire from both battery's + and - is that right ?
     
    Gryd3 likes this.
  5. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    A solution for that problem is using Schottky diodes like this:
    The diode will drop about 0.3V(typ.),should be fine with a 3.7V bat. and IR led.
    BAT-BALANCE.JPG
     
    Gryd3 likes this.
  6. dorke

    dorke

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    Jun 20, 2015
    GHOST HUNTING ???
    Do post a pic if you catch one...:eek:

    Anyways,
    as per my post above a good choice would be this diode:
    PMEG3050EP
    If you have the Battery and LEDs datasheets post them here.
     
  7. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Absolutely, but dorke posted a safer solution that wont require you having to balance your batteries before hand
     
  8. lightman

    lightman

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    Nov 6, 2015
    hi led data
    Emitted Color : Infrared IR 850nm 5w
    Viewing Angle: 135 degrees
    DC Forward Voltage (VF): 1.4V
    DC Forward Current (IF): 1400mA
    Maximum Pulse Voltage: 1.7V
    Maximum Pulse Current: 2000mA
    battery data GTL 18650 3.7v Li-ion Rechargeable Battery 5300mAh
     
  9. lightman

    lightman

    57
    1
    Nov 6, 2015
    would I need a diode on each + wire and what size would I need to get thank you so much for your time and help
     
  10. lightman

    lightman

    57
    1
    Nov 6, 2015
    it will not let me open your diode link can you get them on ebay many thanks
     
  11. dorke

    dorke

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    Jun 20, 2015
    yes, you need 2 diodes on each + wire, as shown in the #5
    the diode is PMEG3050EP here is it's data sheet:
    http://www.nxp.com/documents/data_sheet/PMEG3050EP.pdf

    So,
    you are running your LEDs at about 0.85A each for a total of about 2.5A.

    Your battery isn't very promising...
    see here(test of a GTL 2600mAh):

    http://www.candlepowerforums.com/vb/showthread.php?255943-GTL-18650-Battery-Test-Updated


    And,please watch the following video!
    https://www.youtube.com/watch?v=mbaSAyqhzxc
     
  12. dorke

    dorke

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    665
    Jun 20, 2015
  13. lightman

    lightman

    57
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    Nov 6, 2015
    seems that make of battery are not very good were can I buy the diode I need please many thanks for your time and help
     
  14. lightman

    lightman

    57
    1
    Nov 6, 2015
    your a star I will get two to try thank you so much for your help
     
  15. Colin Mitchell

    Colin Mitchell

    1,417
    313
    Aug 31, 2014
    Basically you cannot drive high power LEDs from a 3.7v battery and include a diode and current-limiting resistor.

    You do not have enough head-room - any ghost buster will tell you that.
     
  16. lightman

    lightman

    57
    1
    Nov 6, 2015
    that's cool Colin I will forget the diode :)
     
  17. lightman

    lightman

    57
    1
    Nov 6, 2015
  18. dorke

    dorke

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    665
    Jun 20, 2015
    Colin,
    Where does your bullshit come from...? :mad:
    Please,check yourself before you post,
     
  19. lightman

    lightman

    57
    1
    Nov 6, 2015
    so was colin wrong dorky?
     
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