Although both cases of adjacent batteries are negative for each cell, if you electrically connect two of them, you're effectively shorting one of the cells if the positive of one is connected to the negative of the next. Hence my concern. I found some scrap T-slot extrusion at my hackerspace, which I think are about the right lengths to make a frame around a bank of cells, so I think I've got the external compression solved. I don't plan to used these cells at more than about 1/2 C rate, so maybe heating won't be a problem. Just saw some thermal images of cells showing most heating was interior, and seemed like the larger flat sides would be the best place to remove heat. So perhaps over-engineering as usual, LoL.High C-rate is mostly creating larger heat then slow charge.
For compression, the thin aluminium walls casing (not CalB) is NOT intended for home use.
It is intended to have structural strength improvement form manufacturers
That's us now... Manufacturer.
Adding a di-electric sheet is always smart. Anti-static plastic would work great.
Casing won't make a short it's negative, if conductive at all.
It won't hurt. The thin blue plastic is not really high capacity protection.
(280Ah is in my book high capacity)
Not so important.
The compression is there to prevent delamination.
Delamination does 2 things:
- reduce battery capacity
- increase risk of instant selfdischarge: all contained current converted to heat.
It's not as safe as it was before bloating.
Slightly bloat, like about one mm., Not a problem.
Large bloat like over 3mm....
Best is to mimic the factory original construction with the materials at hand.
Instant selfdischarge will reach temperatures way over 500c, (but under 660C) infection the neighbor cells, and perhaps enough heat to self combust the plywood.
Or (di-electric) grease, what usually starts to ignite at 350-450C