redilast said:
Also just curious about how long it takes to assemble one battery pack module? Including the time to weld the cells together and attach the BMS, wiring, potting. Like labor time, not epoxy curing time.
That's a question I should probably have a more exact answer to by now. It used to be quite long but I think we've got things dialed in to less than an hour each at this stage, though since a lot of the steps are done in batches at different times rather than seeing a single pack go from start to finish it's hard to say exactly. We had the cell tabbing into the base 10s x 1p packs done by an LG subcontractor so it's BMS, wiring, programming, light pipe bonding, fiberwrapping, potting, demolding, and testing.
Here are a few pics of the current process. There's a bit of origami at first with woven fiberglass cloth to surround all sides of the pack but also not result in loose glass strands that can prevent a seal in the mold plates
We went from hand mixing and vacuum degassing the resin to running a pneumatic powered dispenser with static mix tube and shaved off a fair bit of time and mess with that
Ideally the two plates of the mold pop off without taking chunks of text with them. We found it works best to remove the side plates when the resin is cool, then put it in the oven to soften the resin again before pressing it out of the aluminum center piece so that corners don't chip and flake off.
Since we are doing batches of 5 at a time it gives a good sampling number to make a single change in the process and then see how that affects the finished result in a statistically meaningful way. Just figuring out the optimum type and quantity of mold release to have the sides remove from the mold easily but without looking too glossy involved like a dozen iterations, just compare the difference on the left and the right
Also, for those wondering why the alignment button holes are twice as dense than the buttons themselves, it's so that the packs can be stacked on top of each other with a stagger so that there are more options for fitting them inside the triangular frame cavity of a bike
Cool. Any idea on the price point?
They are listed on our web store site or those interested in that, but I'd like to keep this discussion as a technology and development thread