Experiments in wearable electronic art.

Power: solved

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Current Parallel

Full brightness at 4.18V

Hooray! I did the third test I mentioned in the last post – I hooked up two batteries in parallel, instead of in series, and with no regulator. The two fully-charged batteries were delivering 4.18V. It turns out that’s enough to drive all 50 MinMs to full brightness. And (apparently) due to the slightly lower voltage, the current draw is lower too, ranging from 0.28A to 1.14A over the full brightness range.

This is really great news. For one thing, I don’t need an energy-wasting, heat-generating voltage regulator at all. And for another, I can stack all four batteries in parallel. This has the advantage that if I have a battery failure in the field, I just have less juice – I don’t have to take two batteries offline because of a single failure (as I would in a series-parallel setup).

I have one 1300mAh LiPoly battery, and I just ordered another one. I will put those two in series and run the Arduino Mega off that, and use the four big 2700mAh batteries in parallel to run the LED buss. This weekend I’ll do a test to see how long those four batteries can run the LEDs at full brightness before the voltage drops below 3.8V — that’s where the LEDs will start acting wonky.

Here’s the current-versus-brightness-value graph for the parallel setup.

Current Draw Chart Parallel

Current draw at 4.18V

Author: regenesis

Seattle New Media artist.

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