What should I do with cells?

Hello, I dont know if this is the right submenue but it Will do. So I have a dilemma that I am stuck with in my build. I have to ammount if cells for two packs of 8s3p one is 30q cells and the other one he2

The thing is that they are brand new cells and I tried solder the pack since I don’t have acces to a spotwelder. It worked I think but not good.

Keep in mind I have never put the pack in a build the have half finished solder points on apx half the pack and the rest is untuched. So thing is that I find it difficult and do not know what to do since I cannot do anything with the packs so here are alternatives and I want to check intreates

1 Find someone to help spotweld and fix the packs

2 sell the packs at its current good state( brand new) and buy lipo instead

3 try to solder the whole thing.

I’m just sick of it taking such long time so what you guys think? If you have a bid pm or something

The 30q pack is identical

It looks like your soldering iron is not powerful enough. Id suggest desoldering and finding someone with a spotwelder, those solder joints dont look good.


Agreed, doesn’t look like the solder flowed proper at all.

Ouch… Yes - iron is not hot enough. Unfortunately when you “cook” a cell to get the solder to flow you can damage them… So i’d be careful and monitor for any damaged cells when you get it finished.

I also suggest a bit of flux - stuff helps a ton!

Where are you located? Maybe someone can lend you a spot welder, or a better soldering iron that can do it quickly w/ plenty of watts to avoid damaging cells?

I’d tear it apart and start over. you can test the resistance of the cells if you want to confirm none are damaged.



Im from sweden

Get some rosin solder and flux and a 100watt or higher soldering iron and u will be golden


I vaguely recall someone who had done some calculations on heat damage for 18650 cells and to greatly simplify… i think you need to have your solder done in just 2-3 seconds or you are risking damaging the cell. Maybe they’ll chime in, but hopefully this gives you an idea of how quickly you need to move on each cell.


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that’s about right.

its tricky to solder packs, it takes flux and a hot iron and some quickness. Itsd way riskier than tacking them, but decent spot welders are hard to find.

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so what do you suggest me to do?

Solder can be about as expensive if u need to buy an better iron what’s ur budget on thisp

This is the spot welder i got and its from the same guy i got mine from. I went back through my ebay history to find it for you.

It’s been a real champ.



are you also attempting to mix these two packs into a single pack?

haha I was just talking to you about this one. If anyone has any idea what the correlation between the two digit number and the “set current” knob is, please let me know. Hard to find information on it…

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I forgot to take the picture, but mine is defeinitely set to 40.2 and the current knob is on 10 because i use 15 mil nickel strips and that’s about the most these things can handle. Even then i have to manually add pressure in addition to the spring pressure sometimes to get a solid weld.

The pressure knob on top is pretty crap too… Like it turns forever, how do you know when you reach max pressure?? I’m surprised there’s no quality standard product available on the market.

that knob is useless. Sometimes i tell new people visiting the shop that i need them to turn it while i’m welding a pack or the pack won’t weld correctly, so they turn it while i’m tacking something useless and inside i’m laughing.

I have made a pad on top of the two probe arms with a piece of gauze and some blue tape that allows me to press down on the arms with my finger tip (and not burn it) while holding one side of the pack with the rest of my hand, so i can get a quick three tacks in (for the six spots per cell i do) rather quickly and i know that they took and won’t tear off at the first impact on the box.

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In retrospect I should’ve picked up one of those hand held welders instead.

you mean the 709A with the wand? not enough juice. it just won’t weld that 15 mill with the wand. It needs to be modified with that arduino and lead acid battery mod. I have a 709A in the drawer waiting to mod so i can have a decent wanded welder.

I realize now that these things are meant for making vapes and rc car batteries and shit where the strips are thin and tiny and don’t have to carry 44 volts at up to a 100 amps before blowing a fuse or tripping a BMS without wicking up like toilet paper on a stove.

ah I see, guess i’ll figure it out once I receive my .15 nickel from supower.