First, an update on the MicroQuad project. The USB mystery remains unsolved, but for testing purposes we can just disregard the VCC connection as the ground connection on the USB cable is needed for reference, the VCC line is an optional power source. I posted to the SparkFun Electronics forum, lots of people chimed in to help me diagnose this problem. Most likely though, i was just doing something so subtly wrong I assumed it was impossible to make that error…guess we’ll never know.
While that mystery was building, I did complete a neat little charging box that integrates all four of my homebrew LiPo chargers into one unit, with a fan for cooling, and one power input. It was a REALLY tight squeeze in that tiny box, I practically cut away the entire casing of the little squirrel cage computer fan to get a nice press fit behind the center mounting post. Whoever decided to make the box close with a single screw right in the center wasn’t thinking about how annoying it is to design around! In addition to squeezing the fan in, I had to resolder all the status LEDs at right angles so the chargers could be spaced and mounted vertically for optimal airflow. The fan sucks in air through top vents and blows it out the vents between chargers, also promoting airflow around the batteries should they get too hot.