This is my first ever 21700 p42a battery pack build! Now all thats left is connecting everything!
Rate my welds/presentation 
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Show us your pull test
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Agreed!
@Rhythm, appearances are verrrry often misleading when it comes to spot welds. Multiple pull tests, that leave shards of nickel still connected to the cell, are needed to confirm the integrity of the welds.
Not saying thatās convenient here, just whatās needed IMO to judge your welds properly.
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Oh no! Cāest dommage!
And what a silly thing to say as the OP went through the trouble of posting about this stuff and Iām not the only one to respond. 
FTFY
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Third pic down it appears to show nickel welded to positive without fish paper rings surrounding the positive terminals . Or is there white fish paper rings? Is that a thing?
Anyway Iām a rookie when it comes to battery builds so hoping someone else will chime in on that. Other than that, your work looks very neat.
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I dont have any spare nickel strips to do a pull testš
I dont have the spare nickel for a pull test 
Ah crapā¦i forgot the fish paper rings. Bruh. I really gotta redo all this shit? i very obviously have shitty luck when it comes to ordering nickel strips
I feel for yaā, I really do.
Bright sideā¦It does give you a chance to do the pull tests though. 
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DAMN YOU 
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Are they REALLY necessary tho? 
my 18650 pack did not have them and i went almost a year on it (lasted so short cause i accidentally left my board on and it discharged the battery WAY below a recoverable level)
White fishpaper rings do exist. I bought some from Liion wholesale. I didnt like them.
When protecting cells with blue masking tape which was applied suoer lightly during assembly, ithe rings stuck aggressively to the tape, peeling off layers, messily.
I had to remove a bunch of welds which I thought looked ok, but i had some sharp corners overlapping positive. When i went to use some flush side cut pliers, welds lifted, then i rolled off all my welds, many far too easily, some were ok.
The white fishpaper rings were easiky removed at that point and replaced with regular green fish/barley paper
Rhythm, You are not going to get the answer you want here.
I believe most will also protect the shoulders of the cells with a second layer of fishpaper, under where the nickel is folded over.
Without the rings, you are relying only on the plastic wrapper to prevent a direct short on that shoulder, and when soldering the series connections, that will melt, and your nickel can weld itself to the shoulder in direct short, and you freak out looking for your metal bucket and sand, while fishpaper rings dance around in your skull as you breathe toxic fumes.
When removing nickel, you are supposed to roll it off carefully, in order to not deform the cans, potentially compromising the interior spot weld.
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This puts things in a better perspective! Extremely well written response and i appreciate it! Looks like im ripping the nickel off and putting new ones on
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Itās not that much work once you get started 
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I have bad adhd so staying focused on spot welding is a PAIN even tho its only 10P groups in feels like 100 
@Battery_Mooch soā¦pulled all the tabs off and safe to say im glad i did. A lot of the welds look good BUT a few were barely welded on like you see here. Not too many but still, 2-3 is too many
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I probably just didnt press decent enough on those that didnāt stick. I know youre supposed to apply slight pressure. Not too much not too little
Just a side noteā¦
Necessary? Thatās a judgement call for each of us. Itās certainly on the list of ābest practicesā for pack assembly to reduce risk though.
We have to remember that our personal experiences, or those of anyone, are irrelevant here. The risk exists whether weāve had a fire or not. Think about drivingā¦just because weāve never had a crash doesnāt mean we donāt need air bags. 
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Very valid point! Def glad i ripped these off tho considering a few spots didnt weld properly. Even tho majority looked good there shouldnt be ANY that have a bad weld
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Thanks for the update!
A total PITA to have to rebuild the pack but a helpful experience in the end. It would be great to be able to judge welds āfrom the topā but it really is so much harder to do well than we think. Glad you had a chance to do the weld tests!
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