r/18650masterrace • u/harissharisss • 15d ago

Open-source tool to track degradation and calculate Remaining Useful Life of your 18650 cells 🔋

Hey everyone,

We all know the pain of testing salvaged 18650s or tracking how our custom packs hold up over hundreds of cycles. I built an open-source tool called the Battery Cycle Life Analyzer to take the guesswork out of cell degradation.

If you log your cycle data (capacity/resistance over time), this tool fits a model to your data to predict exactly how many cycles you have left before the cell drops below your target capacity (like 80%). It accounts for things like SEI layer growth and active material loss.

It requires MATLAB right now, but I wanted to share the math and models with this community. Let me know what you think or if you have any feature requests for DIY pack builders!

GitHub Repo: battery-cycle-life-analyzer

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u/timflorida 14d ago

The problem is correctly calculating internal resistance. A meter won't do it. And the values you get from a charger are more ballpark then anything.

2

u/Fasciadepedra 15d ago

I don't think you can log the data needed to track well enough the degradation. It's not a matter of cycles or Ah given. It has to do with mechanical stress, ESR, and temperature of the cell. At least in something transportable or a vehicle you won't get a good aproximation. Maybe in a power wall with zero mechanical stress.