29 Aug Making progress on the practice pack
We’re finally starting to crank out real hardware for the next car – no more of doing just CAD work all day! The first major subsystem on the build list is the practice battery pack. It will allow us to get some early miles on the car without committing to cycling a high capacity, high cost battery pack.
Good batteries are expensive, so we used crummy ones instead. These are the victim Fake123 cells, already assembled into bricks:
Cylindrical cells are usually connected together with spot welds through a nickel tab. In our case, we wanted additional mechanical support and electrical conductivity beyond just the nickel. To that end, Italix has produced some nice tin plated lightweight aluminum plates. Here’s Nathan soldering the nickel to the plates:
Next we clean the cells to prepare them for welding:
…which Nathan also gets to do! Go Nathan go! MK and I also welded bricks, but I like to perpetuate the myth that Nathan builds solar cars all by himself
The end product bricks are held together by screws threaded into little PEM inserts. Battery monitoring PCBs fit nicely on to the flanges bent into the collector plates, also held down through PEMs. Here you can see what the battery “sausages” are starting to look like:
Matt and I also wound inductors for the third revision MPPT, but that project will get its own blog post when it’s further along.