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Thursday, March 10, 2011

As to professional designers, burning out is one of common dangers inside laptop batteries. It is certainly that burning is only a kind of phenomenon instead of root cause. That is why we cannot figure out the resource of accidents when thus occasion happen to us.

The symptom is that the Li-Ion cells are impossible to discharge by itself and output voltage is about 3.9V tested by universal meter. After dissection, it is obviously that the tab of cathode comes to be fracture but it seems to be damaged by external pressures. Then it is urgent for us to have a more accurate analysis.

Before leaving the factory, these laptop batteries have installed with Li-Ion cells of good performance while jellyroll is completed in the internal structure, which shows us that there’s no abnormal accidents to interface of cathode tabs. But from the further research, the corner of cathode tab come into being open circuit by length of 3mm. Due to high work temperature, the tab has already been burn out while no short circuit is existing in anode tabs.

Even so, what causes cathode to be damaged?

From the image, another insider told us that vertical every lap has some obvious traces to be overheating and burn out. If possible, researchers had better have an observation by X-Ray before dissecting Li-Ion cells and it is necessary to check if these components are rebuffed.

In addition, when installing protection circuit, it is most likely to be short-circuited and being burn out. Thereby, once burr of anode is connected to cathode tabs, the conditions will be more dangerous.

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by: USB Phone World