Most of the power box used by electric bike manufacturers on the current market is closed. When the battery of an electric bicycle is charged, it can generate a certain amount of hydrogen and a small amount of oxygen at the end of charging, and the oxygen is accumulated on the top of the power box. It poses a hidden danger to the safety of the power box, which can cause explosions when sparks or heat sources are encountered.
The so-called "battery explosion" essentially means "power box explosion." The fuse (especially mounted on the power box) is exposed to high currents for a long time, which causes the fuse holder to lose its elasticity due to heat, resulting in poor contact, heat generation, softening or melting of ABS plastic on the power box, and sparks. It may also cause the power box to explode. Therefore, the power box air must be considered during design to avoid airtightness.