Brain dump.... when connecting power sources in parallel you should fuse each power source individually. That way if something goes horribly wrong the malfunctioning unit can pop it's own fuse.

Telsa car batteries consist of 7700 individual 18650 or 2170 cells. Each one is connected to it's peers with a 5 amp fuse. If one cell malfunctions it will pop it's own fuse and the rest of the pack continues to operate.

None of the chinese manufacturers are fusing individual LFP 280 or 314 cells. They just strap them together and hope for the best.