Rounded nickel strip controversy

Apparently there is some controversy surrounding rounded edges on nickel strips used to weld P-groups together. Some are saying that it’s an imperative, that you must. Other say it doesn’t matter. I’ve seen videos of people talking about how important it is, and i’ve seen discussion about it even recently.

Lets bring it out into the open and end it once and for all because the vast majority of people on forums and facebook aren’t building packs for people and probably don’t know what they’re talking about, they’re just relaying information they heard or saw somewhere.

I’m going to start off by saying that you don’t have to round your nickel edges. its not a requirement. Sure, it looks nice, but its not at all necessary. As long as you don’t put corners of it beyond the edge of the cell it doesn’t matter. And use fisch paper insulator rings on the positive terminals and you’re golden. Just make sure the nickel is flat, as in not bent up ready to poke something, and not protruding beyond the cell.

I’m not saying “don’t do it”, i’m more saying don’t waste your time thinking its a safety issue and that the pack will somehow explode if you don’t, but if you feel better doing it, by all means do it.

I’m going to go a step further and say almost nobody does it anyway. I’ve torn down i don’t know how many factory packs and i’ve never seen rounded nickel strip in any of them.

there, I said it. Let the drama begin!


Do you recommend nipping the corners off just to be sure?

Perhaps clarify your question, seems he answered it before you asked or I missed your meaning


Not everyone makes a sacrifice to Lord Skatan to ensure safety and longevity with their batteries, I for one rounded out my corners due to my lower status level in the church of skatan.

Can never be to careful with that type of stuff


i do it anyway just so people don’t lose their minds.

but only on the positive end, and using nickel belt, it’s just two corners that need cutting if you cut it along the belt part:

also, meant to share this, but if you’re cutting a shit load of nickel, paper cutters are really useful. i use one of these:


That cutter is exactly what i use. Exacto is the brand i have, and that shit cuts nickel like a boss.

who are these people and why are they losing their minds? If they’re that OCD, why aren’t the complaining about your cell-holder bridge strip alignment on cells that aren’t using holders?

Just send them to me so i can slap them. I enjoy slapping people, so i’ll throw you $5
for every slap i can get in.


i do it. kinda satisfying to cut and at least something that can be done. don’t know why people don’t use button top cells more with the terminals spaced a bit further @thisguyhere why don’t you get some balanced strip and surly people would be more likely to buy them

I dont make mine all perfect and pretty but I do snip the nickel that hangs off the button only on the positive side. Just in case like how you may cross your fingers to make that bad thing not happen but in reality it dosnt do anything but make you feel warm and fuzzy inside.


I mean, if you do it it’s one less thing that can cause a failure.


This is the important point.
Especially if you use a nickel folding method to connect two p groups the corners either need to be rounded or finish on the positive terminal or on on the fishpaper ring. If the corners end inbetween the terminal and the outer ring there is a risk that slightly bend corners get pushed between the positive terminal and the negative cell body due to vibration between the p groups which can result in a short.

what am i looking at here? is there like a slot in the nickel for other nickel to go through?


oh i think you’re referring to the half circle cutouts on the outer series strips, right?

ok so check this out. I used a hole punch to make that half circle then a small hammer to flatten the nickel out again because it warps when you cut it. Always keep the nickel flat.

but the semi-circle cutout is actually there to allow me to step weld the bridge pieces instead of parallel welding them. Step weld are much, much stronger welds and while the nickel welds amazingly to the cells at all times, it often doesn’t do so great on nickel to nickel, either due to the thickeness of the nickel or who knows why, really. I’m not a metallurgist or a chemist, so i can’t really answer that. But step welding like this uses less heat and makes better welds.

I started step welding my east-west series connections to put an end to broken series welds.

I later found though that i didn’t have to cut the semi-circles if i didn’t move the negative probe more than half way across the nickel, so more recently all the weld dots are on the inside half of the nickel instead. It triggered my OCD at first but it makes building quicker and has zero effect on performance or anything else really.

that’s why there is a single weld dot on each side of the strip. That’s where the positive weld probe was.


got ya.

that’s a shit load of work.

do you build all of your packs like this? like, for the completes? must take FOREVER.

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yeah the semicircle thing got old real quick, so i stopped doing it when i realized i didn’t need to.

my sunstone is capable of popping 50 welds per second, so no, its more like pop pop pop pop pop done. The only reason i slow down is because the probes get warm.

I use 25mm width on my “double stacks” so no biggie. No nickel lattice there, just 6 cells welded with one peice of nickel on each side, then three 10mm width strips to bridge two in series side to side.

I can build probably four packs in a Saturday to completion, but i don’t do it like that.

Usually i have cut-n-weld days where all i do is dump out cells, glue them together, cut my nickel, and pop pop pop. Then i shelve them and finish the pack when i’m doing the board.

so I might do three evolve packs and two bioboards packs in one day, shelve them, then do the rest of the evolve mod when i get the board and do the rest of the bioboard pack when i get the board, etc. I do the same with mine. As soon as cells arrive, i’m usually gluing and cutting within a day. There’s half built packs all over my shop right now waiting for boards.


Agree… Not necessary to have rounded corners lol.

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i like the look of it, and since it doesnt rly hurt, why not.

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The reason battery builders here promote trimmed corners is for idiot proof redundancy. If you drill in to new builders that they need to keep corners away from the edges of the positive end over and over again they might actually listen.

I’m all for letting people fail and learn but it’s bad for all of us when that one super idiotic new builder who can’t be bothered to learn properly sees this thread and assumes his nuclear bomb is going to be ok because experienced builders said he didn’t need to worry.

You should do what makes you comfortable chaps but I wouldn’t suggest promoting removing any safety features in a hobby pack. People are reaaaally fucking stupid.


I remember one case last year where a board burned down. The pictures of the battery in the build thread looked not bad at all. No balance wires who crossed or could cut and short out, solid welds, fishpaper on the right place, but no cut and slightly bend corners on a folded nickel pack. With folded I mean this technique

If the vibration caused the corners to bend more and cause a short or not nobody can say for sure. Maybe something totally different was the cause, but for me personally I’d rather cut the corners on the positive terminal than might to risk it to happen.
I‘m not saying it’s necessary for every pack layout, but to say it’s not necessary at all is wrong as well in my opinion. Safety first, especially when building batteries. One board in flames out of hundred is still one too much…


Okay I almost understand but need a little push for my feeble brain. Can you make a pencil drawing or something? I also am annoyed by inconsistent and generally weak nickel to nickel welds.

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