Lithium Ion battery recycling

[gegcorp2012]

I have projects that I work on in different seasons.

Last fall/winter I got interested in Li-ion cells 18650s from old laptop packs when researching solar power for home and off grid.... there is a wealth of knowledge about 18650 and other cell types on the DIY Powerwall forum.

The other thing I do is start new projects and get to some 80% mark before the season changes or I jump to some other project.

The reason I bring this up, is I wanted to show my cell tester and discuss some plans to make batteries(assemblies of individual cells) for scooters or a treadmill motor or (now) DIY kart or minibike projects I never thought I would try.

I made my tester from an old Dell computer case. It has 32 ports, but I had only 20 of them working when I stopped this spring. Actually it was working great, and each tester slot runs independently, so I can be discharging and charging and depleting and resting 20 cells at a time with minimal intervention... just check on it ever once in a while and record the mAh on tested cells and put new ones in to automatically begin the process. It also has data logging using Grafana as an operational dashboard. It uses a Raspberry Pi for the reporting components and the slots are controlled by an ESP32 and proprietary charge/discharge modules that are controlled in banks of 8 over the i2c bus.

It's been a great way to learn more about batteries, micro controllers, single board computers and linux.

More photos if allowed in a single post...

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[landuse]

Dang!!!! This is waaay over my head. Well done on getting it all working though

 

[gegcorp2012]

@Landuse I have been interested in electronics since high school, and got an Associate's degree in Electronics then a techie job, that has turned into a career where I learned more interesting techie stuff for another 35 years.

Still learning today !

So the tester was ~ 75% complete, and I had blowed up some of the tiny surface mount chips by plugging cells in reverse polarity, so I ran it for a few weeks and
I tested about 300 cells in Jan and Feb this year.

I found that most of the cells from the laptop packs that I scrounged from local computer shops are in the 1700 mAh range, and that is too low for use on a Powerwall.

I kind of lost motivation to test more cells until one day at the thrift store, I found this E1000 scooter for less than 10 bucks...

(Always liked any kind of toy with wheels) I wanted to see if I could build a battery out of some of those low mAh cells that I tested. Some of the Powerwall guys solder the cells into packs and a few of them use spot welding machine$. I typically try to make stuff rather than buy it when I can, so I found some YT videos where people made spot welders out of microwave oven transformers and decided to give it a try.

I started on this spot welder rig...
It is in a computer power supply case and it has a microwave oven transformer, a solid state relay and a 555 timer circuit that gets triggered by a pushbutton. There is a variable resistor that should change the pulse duration to control the heat going into the spot welds. (Not completely done with it yet)

And again, I get about 80% done with it and spring time returned and I dropped the project to do stuff outside.

My go kart will have to be finished before I go in for the winter to work on the electronic stuff again.

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[gegcorp2012]

For those interested in recycling and DIY battery packs, here are a couple of documentary style links that are informative, although they were done a couple of years ago.

https://www.vice.com/en_us/article/...ecycled-laptop-batteries-to-power-their-homes

https://inhabitat.com/people-are-using-recycled-laptop-batteries-to-power-their-homes/?fref=gc

Note these systems are massively parallel, like 80p or 100p or even more... that is a challenge for something portable like an EV or cart or scooter, so mobile use cases do better with high drain cells like those found in power tool packs. (Same kind of processing, just starting with better quality cells to build the pack with)


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