It is near that time when I start welding some samples to send to Mooch to test the resistance of spot welded strips and try and answer some questions we have.
Nelvick donated 15 cells to the cause, and 6 of those are in front of me, and ready to go.
I am still deciding on what to weld, to answer the questions we have.
I am personally interested in seeing whether the flux changes the resistance of the spotwelded strip.
It tins the copper in immediate proximity to the weld, and when a lot of power is used, more than is really required for adequate strength tear off tests, the flux can tin the whole area between welds and surrounding area.
I theorize this fills the small airgap between cell and strip that forms between and adjacent to the welds, and thus reduces resistance between cell and strip.
I am thinking I can weld two strips, one pair of welds on each strip, with tabs opposed to each other on the same side of cell. One strip uses flux, the other does not. I got the settings and technique pretty dialed in on the 0.2mm copper under 0.1mm stainless.
Raw dogging copper, no sandwich, no flux, means I need to reestablish the welder settings before making a sample where the result can be relied upon to be comparable.
I am willing to do this but not start off sample making with the raw dogging of copper.
I am pretty sure My welder can NOT raw dog 0.3mm copper, so I would be limited to 0.1, 0.15, 0.2mm and maybe 0.1 and 0.15mm stacked for 0.25, but it seems no one is using 0.25mm copper so perhaps no point, and the stacking of strips has to be a variable.
I am also curious about the 0.5mm stainless experiments. Copper welded under this 0.5mm stainless with flux between cell and copper, seemed to be pressed wide and flat to the cell. The tear off strength required was enormous, and the copper between the welds appeared to be soldered to the cell itself.
I noticed this same tendency when I welded 0.2mm under 0.1mm stainless( with flux) , removed the stainless, and welded more 0.2mm copper, 0.1mm stainless sandwich to that original 0.2mm Strip. When I tore off all three layers. That copper on bottom was wide and flat and adhered to cell as if soldered between the welds.
Tearing off just 0.2mm copper under 0.1mm stainless with flux, the copper does not appear to be attached strongly anywhere but the welds, but the 0.5mm stainless seemed to press and hold the copper flat and wide and perhaps even solder the the copper to cell between the welds.
If this is happening then the resistance between cell and strip should be lower and measurable with the quality instruments Mooch has.
Some of these 6 cells look brand new, and all are at ~3.6 voltage. All but one are Ampace inr22/71/ JP40ās/Am04.
The other 9 Donated cells need a little prepwork and are set aside for now.
Mooch, do you have any designs on the functionality of these cells, like torture testing, or are they destined for recycling soon after testing?
Should I just drain them all the way, or leave them at ~3.56v before mailing them to you?
Iād like to get at least one sample welded up each day and send no less than 6 at a time.
Input as to what others want to see tested are appreciated.
This is a great opportunity, and I want to not waste it, or Moochās time.
On another Note back in August had a test weld cell, a Samsung 50G, that I left outside in the heat and humidity, inside a plastic case. I had used flux and had cleaned flux with rubbing alcohol which diluted the flux and allowed it to creep around cell below the shrinkwrap.
There are no signs of corrosion anywhere. Could be it never got wet enough or that the flux is simply non corrosive, or not enough time has passed. I would not want my Esk8 battery subjected to the conditions this cell was subjected to, but it is not like I had it in the dirt and direct sun and got it wet daily for 6 months. it was just outside in a plastic case in some bushes and forgotten about.
i make the crazy stuff
