rechargeable inspection lamp

Discussion in 'The Projects Forum' started by rsooty, Nov 9, 2013.

  1. rsooty

    Thread Starter New Member

    Nov 9, 2013
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    Hi all. I'm relatively new to electronics so looking for some advice on a rechargeable inspection lamp I want to make. I have ordered 5 1w high power LED's and 20mm heatsinks and will design around these.
    I need help to decide on a battery and how to recharge it.
    The LEDs are 1.2w 130lm 350ma 3-3.2v. I need about 3hours useage from a charge minimum.
    All input welcome.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    If you require 350ma for 3 hours then you will need in excess of 1000mAh battery.
     
  3. John P

    AAC Fanatic!

    Oct 14, 2008
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    Better to think in terms of Watt-hrs when there's a switching converter involved, as there undoubtedly will be. So it seems to me as if it's 15 W-h, 5 LEDs at 1W each, times 3 hours of operation.

    This online listing:
    http://www.allaboutbatteries.com/Energy-tables.html

    says that a NiCd, NiMH or LI AA cell has 1.2, 2.5 or 3.1 W-H capacity respectively. Or maybe it makes more sense to use just a couple of larger batteries; 2 NiMH D cells would give you more than you need.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    My preference would be 4 AAs you can find in any Walmart or hardware store, along with the appropriate charger. These typically have a capacity of 2000mAh or more.

    You'll need a plan for limiting the current to the LEDs. The low-tech approach would be a current limiting resistor on each LED. A more efficient approach would be a DC-DC converter meant for driving LEDs. You can find these on e-bay and they're not expensive.
     
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    That's a good choice. The AA NiMh come in 2000 - 2500 mA-hr rating and they are pretty cheap in two or four packs. They sell them everywhere because the small cameras always used to use them.
     
  6. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Youcould also use a rechargeable single Li cell which has a usable voltage range from 4.2 V (peak full charge) down to about 2.7V end of discharge cycle. They would be smaller and lighter than NI-MH but more complicated to recharge and voltage profile is not as constant as Ni types.
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Post deleted.
     
    Last edited: Nov 9, 2013
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