rechargeable inspection lamp

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

  1. rsooty

    Thread Starter New Member

    Nov 9, 2013
    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


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

    AAC Fanatic!

    Oct 14, 2008
    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:

    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


    Sep 9, 2010
    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
    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
    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
    Post deleted.
    Last edited: Nov 9, 2013