Dr. Lê Viết Thông (second from left) and his students at the Faculty of Electrical and Electronics Engineering at Phenikaa University. — Photo courtesy of Lê Viết Thông

Hazards of fires and explosions are ever-present when working with rechargeable battery-powered devices. Dr. Lê Viết Thông of the Faculty of Electrical and Electronics Engineering at Phenikaa University discusses the issue with the Vietnam News Agency.

What type of battery is commonly used in electrical and electronic devices today?

Lithium-ion batteries, commonly referred to as lithium batteries, have gained widespread use, replacing lead batteries. They're not only prevalent in portable electronic devices such as phones and laptops but also in electric cars and motorbikes due to their high energy storage density, rapid charging capabilities, and increasingly affordable prices.

However, there seem to be concerns about fire and explosion risks when combining these batteries into larger battery blocks. Could you elaborate on this issue and what users should be aware of?

Certainly. Unlike individual batteries found in phones, when lithium-ion batteries are aggregated into larger battery blocks, the risk of fire and explosion significantly increases. This is primarily due to poor heat dissipation capabilities and the complexity  of necessary battery protection circuits, known as Battery Management Systems (BMS). Users need to be mindful of these factors to mitigate the potential risks associated with fire and explosions.

To minimise battery explosions in electric vehicles, what precautions should users take?

The most significant risk of a battery explosion arises from charging beyond the voltage limit specified on the battery. Overcharging can lead to an immediate battery explosion. Manufacturers typically provide a standard charger with their products, ensuring that the current and voltage match the batteries they sell. Over time, these chargers may become damaged or misplaced, prompting users to purchase or borrow chargers from the market without knowledge of their current parameters or voltage compatibility with their vehicle's battery.

This poses a potential fire and explosion risk if the new charger lacks quality or fails to meet the required parameters.

The second significant risk involves overheating during charging or discharging while the vehicle is in operation. Lithium batteries function optimally at temperatures between 10 and 25 degrees Celsius. In extreme temperatures, such as the scorching summer heat in our country, the battery temperature can exceed 60 degrees Celsius, causing deformation of the battery casing, loss of protection, and potentially leading to a fire or explosion. High-speed charging and rapid discharging modes exacerbate this risk.

The third risk relates to low-quality batteries that are poorly packaged and unstable. Inadequate sealing of the packaging allows moisture and air to infiltrate the battery, leading to reactions with lithium and potential fire or explosion. Additionally, as the battery ages, gases accumulate inside it, causing it to swell. If the battery casing is not robust enough, it may rupture, allowing gas to escape and potentially triggering a fire or explosion.

What steps can people take to ensure the safe use of electric vehicle batteries?

Users should refrain from using non-genuine chargers unless they are confident about their compatibility with the battery. When charging the battery, it's advisable to position the vehicle in a cool environment, away from direct sunlight and other heat sources, ensuring the battery doesn't overheat.

It's essential not to use fast chargers designed for high-capacity batteries on low-capacity ones, as this can lead to rapid heating and a heightened risk of issues. Also, avoid leaving chargers plugged in for extended periods or charging batteries overnight without monitoring. While it might be convenient, it can be hazardous if the charger malfunctions, causing an overcharge to the battery.

Equally, users should be wary of replacing branded batteries with OEM (Original Equipment Manufacturer) sold in the market. These products may not meet the same safety and quality standards and could pose a risk.

Manufacturers often recommend replacing the battery when its full charge capacity drops to around 80 per cent of its original capacity. This decrease is due to increased internal resistance, leading to excess heat during charging and discharging. Using batteries beyond this threshold can pose significant risks, so these batteries should be either replaced or used for less demanding applications.

In summary, it's paramount for users to understand the specific risks associated with electric vehicle batteries and adopt measures to mitigate them.

Given the growing prevalence of lithium-ion batteries in electric vehicles and their potential risks after extended use, regular maintenance and battery health checks become even more crucial. Users should prioritise routine maintenance checks, allowing manufacturers to detect issues early on and carry out necessary replacements or adjustments. — VNS