I do this on the side, buy bulk low cycle lithium ion cells, spot weld them together into banks, and make larger packs.
What is the biggest safety problem seen with these?
My packs are 64P, right now 4s but hopefully 7s soon.
My main safety features are per-cell 5A fuses, 100A fuse on each bank under the battery wrap (not removable without cutting the wrap), and keeping the cells and nickel strips under a layer of kapton tape, followed by an ABS plate I designed and printed, then all the wiring, taped to the ABS with kapton tape. Which is then inside of the battery wrap. I use a lower current circuit breaker on the whole circuit.
My layman research suggests that loose wires are the main reason for fires, so all wires are taped down, and the nickel strips are protected from stress. A cell shorting out should blow the 5A fuse. And if I’m careless and bump the two terminals to a conductor while moving it, there’s always a 100A limit. I also only use low-cycled matched cells and currently am charging to 4V and discharging to 3V.
Any other things I can do to make it safer?
We’re used to viruses that have narrow cell types they can infect. Rhinoviruses can infect mucus membranes in the head and maybe throat. Influenza can infect the same plus lung tissue.
These coronaviruses can infect so many cell types. Because it’s spread via the air, it almost always infects mucus membranes of the head first, then moves to lungs (or maybe it infects lungs first in some people). So we think of it as a respiratory virus at first.
Now we know it can infect tissues of the gut, fat, T cells, and the testes. There was a wave of orchitis/epididymitis that was discovered to be coronavirus caused. I’m not sure if it’s considered COVID, I think COVID is the respiratory disease caused by coronavirus, but not sure about other diseases. Similar to how the varicella virus causes two diseases: chicken pox and shingles.