wiki/ news/ 2013-05-29 - Battery pack shenanigans, FC cart

Battery Shenanigans

Several months ago, we blew one of the battery pack's internal fuses (there's one 20A fuse per battery) when we plugged the battery pack into an Agilent power supply that was off. Yes, Agilent supplies dead short when their off. We're sure there's some good reason for this, but @#$!!$(@$ that sucks.

Tonight we (Nathan and Andrew) removed the battery pack in order to replace the fuse, and ran into, uh, problems. First of all, the each of the cells in the Lithium Ion Polymer battery pack had swelled so much that we couldn't actually remove the pack from the 3D printed enclosure. We had to saw (carefully!) through the corner to pop the case open and let the cells out. When we removed the cells, they were so puffy that you could press down on the top/bottom of them and feel some kind of gas internal to the polymer bag. Not great. The interwebs says that it's some kind of oxygen generation from charging or discharging too quickly, and that you might fix this by better charge management, but that you really shouldn't use the batteries. Well, heck.

So we removed the batteries, and took out the battery boards in each battery. Turns out we blew one fuse, but baked the rest to the point that they needed to be replaced as well.

New FC Cart

Nathan came up with the brilliant idea of a "Flight Computer Card", where we had the FC setup and ready to go, including wheeling it around. Here's our attempt: