AA batteries are surprisingly potent little things, and a set of four can comfortably run about a meter of LPD8806 LED strip or one strand of 25 12mm pixels for a couple hours or more. You can go beyond this to create larger projects, with some forethought…
- A fully-lit 1 meter strip can demand close to 2 Amps, but the batteries and diode are only rated for a continuous output of about 1 Amp. You can push beyond this for brief intervals, but it can’t be sustained. Design your software so that the LEDs seldom or never exceed this level, using the 60 mA rule of thumb.
- Voltage diminishes slightly along the length of a strand. And when voltage drops too far, the LEDs will show dim and muddy colors. When using long runs of LEDs, we recommend adding an extra power tap every meter or 25 pixels to reduce this voltage drop.
- Remember that “off” pixels still need a tiny bit of current for the driver chips…about 50 mA per strand or meter…and another 25 mA for the microcontroller. Factor this into your battery calculations and software design. Large setups may be using hundreds of milliamps that are never seen, but continuously pass through that diode with its 1 Amp ceiling.
- C or D cells have more capacity for extra run time (up to 12,000 mAh with top-of-the-line NiMH D cells). We don't stock battery holders for these, but suitable ones can be found at Radio Shack and elsewhere. The 1N4001 diode is still rated for 1 Amp continuous output though…so for a larger project with many LEDs simultaneously lit, you might need to swap this out for a beefier diode such as a 1N5400, good for up to 3 Amps. This may get hot, so don’t leave it exposed to curious fingers.
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