Processing cells

The general steps are like:

• Find laptop or other type of packs with 18650 cells inside. Be polite and drive around and ask shops and friends for free packs and if needed pay them a dime or two. Most places are alot happier if you pay some for it.
• Open the packs and clean them. Make sure to be gentle and dont destroy anything in the packs itself.
• Strip of all electronic and remove the tabs
• Do a capacity and voltage test of the cells. Make sure to bin the ones getting hot or doesnt respond well to the test
• Sort the cells in 100mAh categories and make sure they are fully charged
• Let them sit for a couple of weeks and then retest voltage. They should not have been dropping to much. If below 4.05V then toss them.
• Use the ones left :)

Processing cells is a time consuming task. Whats important when you do process them is that you do it with one and the same type of tester. Do not use 3 different types because that will give you 3 different values.

Example is that Im using my Opus board for testing where i have 10 Opus chargers.

if you use different testers you can easily have 20% or more difference in the capacity reading. With that said for instance the Opus chargers can also vary alot internally. You get what you pay for kind of :)

For instance the contact surface when meassuring the Internal resistance can make numbers between 100-200mOhm easily. Temperature and other factors are also there.

I use my numbers from the Opus only as a “number” Where i say that 2000mAh or above is good for my wall. This is something that you yourself need to decide. Why do I say that? Because if you got cells that from start was 3400mAh then 2000mAh may not be working for you since that is a major degradation.

Cleaning the cells can be an issue sometimes but this is how I do it:

In generall its all about the purpose so cleaning depends on that.

And if you want to compete in terms of opening packs here is my attempt to open 10 packs with 6 cells in each.

The processing flow can be found below. This is how I do my processing.

if you are interested in any of the gear I use in the videos just check the description for links :)

Happy powerwalling and collecting cells!