Everyone knows that an electric vehicle battery is a consumable, but what should you do if it swells while charging? Do you know the causes of this swelling? If not, let us find out together.

1. Swelling caused by overheating

The causes of battery overheating include unreasonable battery selection and thermal design, an external short circuit that raises the temperature, or a loose cable connector, and these should be solved from both the battery design and battery management sides. From the perspective of battery material design, materials can be developed to prevent thermal runaway and block the runaway reaction; from the perspective of battery management, different temperature ranges can be predicted and assigned different safety levels for graded alarms.

2. Swelling caused by overcharging

Swelling caused by overcharging means that the battery management system itself lacks a circuit safety function against overcharging, so the battery keeps charging even after its BMS has lost control. For this kind of overcharging, the first remedy is to locate faults in charging, which can be solved through full redundancy in charging; the second is to check whether the battery management is reasonable, for example, whether the voltage of each cell is monitored.

3. Swelling caused by an internal short circuit

Impurities from manufacturing, metal particles, the expansion and contraction during charging and discharging, and lithium deposition can all cause an internal short circuit. Such a short circuit develops slowly, over a very long time, and it is hard to know when it will cause the battery to swell.

To solve the internal short-circuit problem, first find a manufacturer of good quality and choose the battery and its cell capacity; second, carry out safety prediction of internal short circuits so that before thermal runaway occurs, the cells with an internal short can be found. This means you must identify the characteristic parameters of each cell, and you can start with consistency: cells are not consistent, and their internal resistance is not consistent either, so as long as you find the deviant cell among them, you can identify it.