I dreamed of the moment I’ll finish my own batteries like you guys, and there is still a lot to learn, but hey, it’s also a lot of fun to build your own battery
firstly, I had quite a successful endeavor with my setup which had to be a little upgraded. the story as follows:
I’ve been riding some 3s lipos in the past on my first AT before it got ass-cracked
so, few months after that I had to do assemble my kweld and some other pieces to do my first fob
well, apart from the hot-glue holding the batteries, I’d say not that bat!
but then I had to get rid of the lipos. I just had a bad feeling about having them swollen like that while staying in dorms, where a fire would not be pleasant at all. so the batteries slowly deceased in the sink for a few days. great present in the bathroom for other roommates. the afternoon after I put them in the water I just received a message on messenger “Andrew?” and the picture attached
incredible how long it takes for them to self-discharge in saltwater. seems that they either have quite more energy stored than my brain would naturally perceive, or the process of breaking molecules of water into oxygen and hydrogen is not particularly energy demanding and takes a long time. and also, the green blue copper salts
here some of the sad story:
so, new battery, I tried car battery with some really jacked up connection, just 10awg wire, and some wood clamps.
too bad idea, too much resistance, too long welding time, too fucked-up everything. welds would not stick and I had dented the cell tops and bottoms. these were for times of 60-90ms on the kweld, with about 800-1000Amps of current in. that was something about 70J. that was really stupid. now I’m just worried that the cells might be internally damaged.
but then I changed few things
8AWG stock wire to 35mm^2 wire (about 2AWG) and things were changing.
I had to find an electrician in Prague just by calling numbers, and the guy I called gave me a number to another guy, I called him and he said he knows a guy who has the tool and does this job
after this, I finally had a decent connection. however, the shitty amalgam from definitely not copper just evaporated after at an impulse of current.
so I had to change the output wires back to the stock k-weld 8Awg with the propper copper electrodes
but after that and some electrode isolation with zip-tided tissue after some finger burns, I finally had some welds I’m happy with
it is a triple stack, I designed for roughly 100A of discharge. I’m sure I might be far away from that, but I have peace in mind with this margin of error or possible high safety factor. also, what do you think of the single-layer connecting ends? I see it as a balancing piece, as none to low current should be flowing through there, most of it would de flowing though the triple stack. next time I’d go for a different setup, where there is more space between the parallel groups than two cells - that would require fewer layers.
I might say something about the pack itself - 12S6P from P42A molicells. I was especially keen to have this orientation to get the benefit of having the positive and negative on the same side of the “box”.
well, this was the result
then some fishpaper
and balance strips and some cable management love
some more kapton tape and in the box she goes
I’ll be really glad to hear some feedback, on which parts you think are well designed and also what could be improved. I’ll also write a build thread about what this will be powering!