Another few hours of work this weekend saw the Staff cut loose from it’s moorings for the first time.
One of the biggest challenges on this project is power. The LED strips are 55 tricolor (very bright!) LEDs driven by WS2811 controllers. The strips are powered at 5v. Doing some quick load testing on the initial strip (and some online research) showed that each LED has a maximum draw of 60mA, so a 55 LED strip can draw a max of 3.3A @ 5v, and 6 strips can draw something like 20A @ 5v if the entire thing is at full brightness. That’s a heck of a lot of current. Compared to that, the Arduino wouldn’t be drawing dink.
I had to balance battery capacity with weight (this thing is meant to be carried in one hand after all). I considered using D cells, but they’re just too heavy. I ended up with 8 NiMH C batteries ( http://www.amazon.com/gp/product/B001AX1UQO/ ) from Tenergy. These are ranked at 5000 mAh @ 1.5v. I ganged them in groups of 4, connected in parallel. This gave me 5Ah per group, or 10Ah total. With a draw of 20A, at full power, it works out to only half an hour of uptime. Now, there’s a lot of loss in this as well, so realistically, at full power (255,255,255 values on all the LEDs) I expect to get only about 15-20 minutes of use.
In general use, I don’t plan on using this in BLAZING WHITE MODE for more than a few seconds at any given time, but ongoing running will run the batteries down. The other night I ran the staff using a ‘randomized’ pattern for a good 15 minutes on those batteries without any ill effects, and saw no problems (Check out the video here: http://youtu.be/LNbIwpk5vdA )