LED upgrade

journal > 2015 > LED upgrade

Upgrade battery powered dome lamp from incandescent bulb to LED to get a brighter light with better battery life

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battery-powered dome lamp
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1 Watt White LED (made in Taiwan) 3-4 V 350mA A000
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LED and 4.5V bulb
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LED installed

Using 4 (used) NiMH AA batteries fully recharged provides the LED with 3.6 V at 686 mA, which is over its rating.

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current increases rapidly with voltage
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rewired for three AA cells

With 3 Ni-MH cells in series, the circuit draws 3.14 V and 243 mA, so very close to the ideal 1W rating.

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NiMH cell current drop off
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LED lamp installed
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basement stairway illuminated
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bright stairs
  before after
cells 4 AA 3 AA
chemistry alkaline NiMH
capacity 1800 mAh (x4) 2850 mAh (x3)
voltage 1.5 V (x4) = 6V 1.2 V (x3) = 3.6V
resistance 0.15 Ohms (x4) 0.02 Ohms (x3)
rechargeable no yes
Technology incandescent LED
voltage rating 4.8 V 3-4 V
Keyword: project
Dates: 2015:09:12 - 2015:10:23