https://m.aliexpress.com/s/item/32814189809.html?spm=a2g0n.search-cache.0.0.2e3aa29b6tGUot#autostay
I’m not too good with this stuff but I thought it 2as kind of cool.
They are individually tabbed…no use for us
Oh, I thought that meant you could just solder the tabs together.
You could but I doubt they’re pure nickel and you still need to connect in series,those tabs won’t handle series connections.
Also I would never trust welds that look like this Horribly skinny too
Mine look like this
@Sapphirinia if you bring me cells I’ll spotweld them in whatever configuration you want while you wait (30-45min)
4 Likes
Hm I was gonna keep quiet but others might be curious.
Is that 10mm 0.2mm pure nickel, 2 layers? Is it enough to handle the current?
On a 3P I find single layer more than enough, on 4+ I double up Also I feel it makes a difference having the series nickel covering the length of both P, vs just nickel between the last and first cell
I’ll be doing a write-up of the all the 30q packs I’m making after I’m done with them
This is so confusing, I’m trying to figure out how much conductor I want in my packs.
from 18650 spot welding -how to- ULTIMATE REPOSITORY | Endless Sphere DIY EV Forum
Resistance is a function of volume, so cross section times length. .2mm * 10mm = 2mm^2. On the chart (being lazy), .3mm * 7mm is closest to 2mm^2, which is: <10A optimal ~15A acceptable
20A poor/hot
Your photo shows 1 series connection between parallel groups, so that connection carries the full amperage of the pack. I know I pull 60A out of my pack quite often, though only a few seconds at a time.
The table above also looks very conservative to me.
I feel like I need to build a proper DC load and test this for myself…
That chart always looked very conservative to me lol Simplest real-world way I’ve found to see if your series connection isnt enough is if you’re getting more sag then expected under load, though not “scientific” you can spot it
Another thing that’s always bugged me about that chart…what about length? Does that assume 1mm? As well as weld spots, 6 will carry better than 2
1 Like
I have a FLIR so I can get approximate temps, but I don’t have a way to generate the load in a controlled fashion…
A 2000watt 36V to AC inverter would do the trick