Presumably ultrasonically welded: the wire is pressed to the bus bar and vibrated rapidly to friction-weld it in place. The cell wires are similarly welded to the cells and to the bus plates; no one solders or electrically welds wires like this in production applications.... Turns out the wires were coming loose from the bus bars.
It looks to me like the connections were made with some sort of spot-welding process.
I looked at the wires under 80x magnification and they look like they have been hit with some sort of tiny, futuristic panini press Any thoughts as to why these connections would fail like this? It seems like the fact that they have been stored outside their sealed, moisture controlled enclosure for 10 months could be the root cause of the corrosion... Do you know what material is used to make the cell level fuses? Those connections do not show any signs of being a problem, but they also look like they could be made of the same material as the bus bars. I wonder if simply getting condensation on the copper-aluminum junction was enough to wreck them, and if that is the case, why they didnt just use aluminum wires...Presumably ultrasonically welded: the wire is pressed to the bus bar and vibrated rapidly to friction-weld it in place. The cell wires are similarly welded to the cells and to the bus plates; no one solders or electrically welds wires like this in production applications.
Great progress! Assuming you have checked and the cell voltages and the bms agree. If so, why not turn on the balancing function on all the other cells so as to lower everything but the deviant module? It may take a while, since the balancing current is pretty low, but it should work over time and you can play with the BMS functionality and learn how fast things will change. Just an idea.Okay, string 2 is wired.
I hit a few snags, but it went a lot faster than the first one. I applied power to my BMS, and against all odds, the wiring was all correct!
I outlined in red the deviant module. I will have to consider my options for how to charge the strings up independently to get them balanced. It will probably just be a matter of reducing the size of the BMS and swapping around the harnesses...
Anyhow, this feels like a big milestone.
Goal #1 Mount batteries
Goal #3 Check voltages with BMS
Goal #2 wire main contactors to my power switch (which will mean routing some conduit and setting up my HV Box) - is up next