As electric vehicles become more popular, there has been an increase in the number of instances of these vehicles catching fire. There have been over 20 recorded occurrences of Tesla battery fires, with some resulting in fatalities. Tesla has acknowledged the problem and promised to include fire-related costs in its warranty.
Now such concerns about potential fires are projected to grow as the number of electric vehicles grows, and dependable ways to prevent these fires have yet to be discovered.
To begin with, let’s dispel one of the most popular myths: fires are caused by hot summers and inadequate thermal management. That is not correct.
Thermal runaway is the cause of the recent fires we have seen. Li-ion cells must reach several hundred degrees Celsius before experiencing thermal runaway.
EV Fires: The Culprit Behind The Flames
The causes of these fires are not unknown. They all result from a phenomenon called ‘Thermal Runaway’. Many variables can contribute to thermal runaways, which can result in flames. The conditions conducive to thermal runaway are produced by battery abuse resulting from mechanical, electrical, and thermal defects.
Also, Improper operating methods, such as overcharging and over-discharging, can hasten battery degeneration, increasing the risk of thermal runaway.
But Interestingly, Most current batteries shut off automatically around 45-55°C. Even if these temperature monitoring mechanisms fail, there will be no thermal runaway (fire) because batteries cannot overheat by a few hundred degrees Celsius during normal operation. A faulty thermal design battery will experience a temperature spike of 30°C above ambient.
EV Fires: What Causes EV Batteries To Catch Fire?
Before we go any further, let’s establish three key criteria for every battery:
- Battery Life
Yes, Hot summers and poor thermal management have an impact on performance and life, but they do not cause fires. It’s like using your phone on a hot day after leaving it on the dashboard of your car – it’s slow, hot, and shortens its life. Yet they have no bearing on safety!
#1. Short Circuits
Short circuits cause uncontrolled current in 99% of battery fires. This is the only scenario in which cells reach temperatures beyond 100°C.
Fun fact: When cells short circuit, they emit combustible gases through a process known as cell venting to lessen the likelihood of thermal runaway.
Short circuits occur for three reasons:
- Low cell quality
- Inadequate battery design (the way cells are connected & packaged)
- Poor BMS (Battery Management System)
Now let us dive a bit deep into the above three.
Poor Battery Quality
An “internal short-circuit” can occur as a result of poor cell quality. There may be an error or short circuit with how the anode, cathode, and separator are bundled together due to manufacturing flaws. An internal short-circuit caused by an unintentional contact result in an unregulated current, eventually producing large amounts of heat and hence fire.
Poor Battery Design
The fundamental root cause of short-circuiting is not always cell quality. Battery design, particularly packaging, has a significant impact on safety. Packaging relates to how cells are assembled, as well as how they are electrically joined and physically held together.
Inadequate BMS = Overcharging
When you charge a cell, you move it from a lower voltage to a greater voltage, which generally corresponds to the 0% and 100% charge states (SoC). Voltage thresholds differ depending on cell chemistry:
LFP(Lithium Iron Phosphate) voltage ranges from 2.8V to 3.6V.
NMC (Nickel Manganese Cobalt)voltage ranges from 2.8V to 4.2V.
Even a 0.05V overcharge of NMC can significantly enhance the growth of Lithium dendrites.
Overcharging is caused by poorly designed BMS hardware (poor sensing and accuracy), a lack of BMS intelligence, or poorly written BMS software.
Most EVs nowadays charge blindly. These modules have a capacity of 2-3kWh and are managed by antiquated analogue BMSs that are stupid. They are no more intelligent than an Amoeba. If a cell goes rogue, present BMSs have no idea how to handle it, resulting in overcharging, dendrite buildup, and eventual thermal runaway.
#2. Defective manufacturing
A manufacturing fault is one of the most common causes of EV fires. Many companies are now launching E-Bikes and putting cheap prices on them. Internal components and parts used to build these are inexpensive and of poor quality. As a result, they begin to fail as soon as the bike begins to rev. Also as we have mentioned earlier that how the packaging of the battery is done? where it is kept etc all are important when it comes to the safety of the vehicle.
#3. Over Heating
The primary cause of an EV catching fire is excessive heating. The EV’s battery heats up, and when the heat combines with the fuel(any substance that can catch fire), the battery explodes in flames.
#4. Rough Treatment
Last but not least, an EV that is handled roughly will fail quickly. If you do not clean the vehicle, dirt and grease will accumulate on the interior components, perhaps causing a fire. If you do not service the vehicle on time, internal problems may develop that go unreported. This would eventually result in a fire. Also, driving your EV roughly increases the likelihood of a fire.
How can you avoid an EV battery fire?
There are some practical methods for preventing your EV battery from catching fire. Here are some pointers:
#1. Invest In a Quality Product
This is the most effective technique to keep your vehicle from catching fire. As previously stated, there are many companies in the EV industry these days, and to keep ahead of the competition, some are foregoing safety measures and launching products with less study and testing.
Nevertheless, several manufacturers are selling vehicles at significantly reduced prices. When selecting an EV, use your discretion and buy a nice one from a reputable motor manufacturer. Do not buy a car or bike based solely on price, as the cheapest option is rarely the best one.
#2. Charge Properly
Secondly, keep in mind to properly charge the car. An overheated battery back is one of the most common causes of an EV fire. Try the following to avoid this:
Charge the battery only to 80% capacity. When the battery is overcharged, it becomes extremely hot. You’ll be able to control the heat in the pack if you don’t charge it completely every time.
Do not allow it to discharge. Charge it again as soon as your battery reaches 20% capacity. This would allow it to perform properly and last longer.
#3. Maintain A Constant Speed
The battery is put under a lot of strain when you drive aggressively, with rapid acceleration and braking. It gets quite hot, which might cause sparks. Aside from the smoke that comes from the powertrain, a lot of sparks and heat can also start a fire. Drive at constant speeds to keep the car safe.
#4. Proper Servicing
Service your EV regularly to guarantee there are no internal problems. If there is a little issue, the mechanic can detect it early on and prevent it from growing into a significant issue and triggering a fire. Many accidents occur as a result of people ignoring little problems and allowing them to escalate into major concerns.
If you follow these easy instructions, your EV will be safe, and you won’t have to worry about fires. If you find any flaws or weird behavior, take the vehicle to the nearest service centre and get it checked out.