The battery is the core component of an electric vehicle, and battery swelling is no stranger to riders. In recent years swelling has been seen so often that many consumers are troubled, because once a few cells in a pack swell, the whole pack has to be replaced. So what exactly causes electric vehicle batteries to swell?

1. Poor battery quality

Quality problems are often the first reason riders think of, and they cannot help assuming that the battery itself must be bad, otherwise how could it fail so easily. Indeed, in the mixed market of electric vehicle batteries many companies have limited manufacturing capability, with uneven electrode coating and rough production processes, and they leave no gas gap inside the battery. Such batteries swell very easily.

2. Safety valve pressure too high

People in the industry know that electric vehicle batteries are fitted with a safety valve for protection. When the internal pressure rises, the valve opens automatically to release pressure and keep the air balance inside and outside. If the valve fails to open normally while pressure keeps rising, the long-term imbalance of inside and outside pressure will result in swelling.

3. Overcharge and over-discharge

Many batteries are used in series in order to get more capacity. Note that frequent overcharging and over-discharging in use will make gas recombination inside the battery poor and trigger violent short-circuit-like reactions, producing large amounts of heat that decomposes and vaporizes the electrolyte, so the battery swells up.

4. Charging current too large

Normally, batteries from legitimate manufacturers have a specified charging current. If the charging current exceeds this reasonable value, deposition on the plates happens too fast and chemical reactions become incomplete. Then the internal temperature rises quickly, and if gas is not released in time the battery naturally swells.