I suspect the solder flowed to close to were it was flexing and stiffening it all up and putting the flex in one very small. space as it flexed repeatedly in this small area it started braking the strands. Increasing resistance increasing heat and work hardening the copper. This ends up been a self perpetual cycle that escalated untill catistrofick fault you end up with there. This is what I think most likely happened from working on large factry mechinary that vibrates and seen similar results with stranded copper.
I think your better of with the copper braid over the silicon wire just make sure thereās more space between the stiff soldered area. (I prefer the pre tinned stuff personally as I fined it easya and quicker to get the solder contained were I want it for a better more controlled concetion)
Disclaimer this is my opinion Iām sure otheres will have different or contradiction ones i recommend reading them all and making your own mined up to what you think is best.
I ordered the 30Q with the Tags from nkon.nl every row of my holder has 8 batteries and there is a total of 6 rows (8x6 = 48 cells = 12s4p). I connected 4 of them in parallel and then connected to the next pair of 4. So it means each row has 2 parallel pairs. For connecting the parallel pairs I used a thicker wire because the tag only would not have a desirable amp rating by itself.
So I just soldered the parallel pairs together with the tags. If you have a soldering iron that can get hot enough and you sand the tags a bit then it will hold up quite well.
Just donāt want to invest in a spotwelder that I only use once every 2 years.
The case and everything is printed on my 3D Printer (Material PLA)
To improve shock absorption the cells have acrylic and hotglue between the cells.
There is fishpaper between the ppacks but only where terminals touch in the picture below there is fish paper where itās red but not where itās blue.
but itĀ“s the place where the battery flex.
because of this flex the packs can rub on ech other and damage the thin plastic cover around the cells.
as you for sure know the main part of the outer cell is the negative pole. so if two packs damage there isolation next to each other over time you short your packs.
@Andy87 Thanks for pointing that it i will definitely take that into consideration for future builds and possibly add some fish paper there on this one. however there is kapton tape over the positive cap and there are 2 layers of shrink wrap one over each of the parallel packs that fold inward a bit and covers most of the positive cap and one over the 2 parallel packs that are next to each other so the chances of it shorting that way are very slim.
@deucesdown I get that but the main problem would be the positve cap touching the cell body which is negitive but if the positive cap is covered it cant short on the negitive cell body.
If you have a connection from positive on one to negative on the next group in series, and the wrap wears between those groups, the cell bodies contact and essentially short positive of the first through the negative (body) of the next which is the negative of the first. Itād be like shorting positive to negative on the first group directly, just via the cell bodies.
Issue still remains I believe because the cells that are stacked āfurtherā into the series donāt actually have 0V on the GND side they have all the voltage from packs before them.
@Andy87@deucesdown@wafflejock There is a very slight chance this will happen but just to be safe i will add fishpaper in this area on this pack and in future packs!
