Design, Build, Test, Iterate

Removing a bad cell from a lithium-polymer battery

One of the cells in my lithium polymer battery rapidly started losing capacity a few days ago. I ordered two new batteries, but I needed power in the meantime.

Battery with plastic wrap peeled off.

Battery with plastic wrap peeled off.

It was trivial to open up the battery and remove the faulty cell, since the other three cells were fine. The battery is now effectively a 3-cell battery, which is not as efficient, but it will do for now.

The imbalance probably resulted from my neglect. Especially considering that I used the battery without any kind of low-voltage alarm, I probably drove some of the cells below 3 V during use. Furthermore, I never balance charged the battery (which I always will from now on), so the small imbalances built up to a serious amount.

Categorised as: Projects

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