It’s not the first time that Tesla cars catching fire were reported, and when we dive deeper into the cause of most Tesla combustion accidents, everything points to Li-on batteries. So are lithium ion batteries really that dangerous?
In this article, we’ll dive into the facts of are lithium batteries safe? What can fail a lithium battery, how to deal with small-scale combustion, and lastly, what the safest lithium batteries are.
Table of contents:
- Are Lithium batteries safe?
- Factors that can cause lithium battery failures
- Ternary lithium vs. Lithium phosphate iron battery, which is safer?
- How to put out a burning lithium battery?
- How to make sure phosphate iron lithium batteries are the safest lithium batteries?
- The safest lithium batteries from Renogy
Are Lithium batteries safe?
Not all types of batteries are safe. Lithium batteries can burn and explode, but the chance is small. Lithium batteries manfufactured by professional suppliers have a set of rigorous and safe manufacturing process, which has minimized the risk of any flammable accidents.
Factors that can cause lithium battery failures
There are three predominant factors that can burn out a battery.
This is the most common problem for powerpack failures. Abused usage of the lithium battery, occurrence of lithium dendrite due to over-charge or discharge, dust during the manufacturing process, and so on, all can post a possible factor for a pierced septum inside the battery, which can quickly catalyze a slight short-circuit. Moreover, the short-circuit will soon lead to a series of chain reactions, giving rise to worse short-circuits, higher temperature, runaway current, and lastly, a thermal runaway, which is the culprit for a battery fire or explosion.
Another possible reason for a battery breakdown is the external short circuit. However, the hitch rarely happens on lithium iron phosphate batteries as they are often equipped with fuses and a battery management system (BMS). In addition, most lithium batteries are designed to withstand an influx of currents in a short time, which means, in most cases, they are strong enough to avoid the risk of short circuits caused by any exterior short-circuits.
Under high-temperature environments, for example, in a fire, decomposition reactions can be catalyzed inside lithium batteries. The process can produce decomposition products that can react with the cathode and anode of the battery, generating a lot of heat. More than that, the battery separators will melt down, coupled with internal short-circuits and more heat release. As the multi-reactions keep going on and the accumulation of an abundance of heat, the battery cell will end up bursting, which will then be followed by electrolyte spills, the fuel for conflagrations.
Ternary lithium vs. Lithium phosphate iron battery, which is safer?
There are many types of lithium batteries, for example, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese cobalt oxide, and more. Ternary lithium and lithium phosphate iron are the two most common choices for vehicle use. More specifically, ternary lithium batteries work best for renewable or electric cars as they provide higher energy density and long-lasting discharging, while lithium phosphate iron batteries are more suitable for RV, where safety is the top consideration. Keep reading, and you will know why.
Ternary lithium battery:
Ternary lithium powerpack is geared with an anode composed of oxides, nickel, cobalt, and manganese. When temperature surpasses 180 °C, the anode decomposes and produces oxygen in quantity. Once the oxygen meets solvents, there will be a large number of gases, heat, and smoke coming into being and then getting trapped inside the battery case, which will lead to the battery bulging, bursting, and spilling out combustible electrolytes. The process is called thermal runaway.
It is very easy to catch fire when the combustible electrolytes meet oxygen, and the fire is hard to put out. From thermal runaway to a blast, the process could take only seconds. Even though it can be quenched temporarily, as long as the battery is still experiencing chemical reactions, the fire will come back continuously. The only solution is to wait till the chemical reactions completely consume the electricity stocked in the battery. However, waiting can be the cost of your property burned to a cinder.
Key takeaways: Ternary lithium batteries are easy to burn ferociously, and the fire is hard to put out.
Phosphate iron lithium battery
With an olivine phosphate anode, the phosphate iron lithium battery has better thermal stability, which means that when put in a high temperature or overcharged, their internal structure will not collapse easily or horribly like their ternary counterparts. Their temperature resistance point can go up to 700 to 800 Celsius degree. Even when the anodes start to submit to the high temperature, they won’t generate many gases. That being said, phosphate iron lithium batteries are much safer than ternary batteries.
Key takeaways: Phosphate iron lithium battery will not cause severe conflagrations. Find more information about phosphate iron lithium batteries in Why Choose A Lithium Iron Phosphate Battery?
How to put out a burning lithium battery?
If you are experiencing a lithium battery thermal runaway, don’t panic, here are some ways that can help you put out the fire fast and with ease.
You can use a dry powder extinguisher or but do not use it solely. It will not be powerful enough to put out a fire caused by a battery, and they can only fight the flames on the battery’s surface. Under the surface, high temperatures are nurturing fires.
Using water is a better solution. Water can quickly seep into the battery and cool down the internal heat. When the water supply is adequate, it is recommended to shower the burning battery continually until the internal heat is completely cooled down.
Moreover, sand can also be a lifesaver. It helps sedate the chemical reactions inside the battery effectively.
How to make sure phosphate iron lithium batteries are the safest lithium batteries?
Are lithium batteries safe? Especially LFP batteries safe? The best way to verify this is to give it a professional test.
Renogy is an expert in designing and manufacturing phosphate iron lithium batteries. We now have a range of phosphate iron lithium batteries with different risk-proof features for our customers to choose from. To prove the safety of phosphate iron lithium batteries and verify the quality of Renogy products, we will use one of Renogy’s best lithium batteries to display the whole testing procedure.
Test #1: 130°C high-temperature testing
We detach one Li-ion cell from the Renogy lithium battery (big batteries are made up of a number of cells packed together. ) and put it into a constant-temperature drying oven in our lab. With the temperature quickly rising to 130°C, we will see what will happen to the Li-ion cell under the drastic temperature change.
As a result, the only result we can see with the naked eye is a swelling battery cell. No liquid leakage, fire, or blasts are detected. That being said, Renogy lithium-ion batteries are safe in high-temperature environments.
Test #2: -7°C low-temperature testing
Lithium batteries are designed to stop charging when their working temperature falls below zero Celsius degree, for the purpose of effectively prolonging their lifespan, similar things you can observe from your smartphone which usually shuts off at a subfreezing temperature. Explained in a more professional way, charging a lithium battery at a low temperature can cause a plating of metallic lithium forming on the cathode, namely "lithium precipitation". The deposition of the substance can pierce the septum and cause a short circuit.
In this test, Renogy’s battery shows unique advantages. The smart lithium phosphate iron battery features proprietary self-heating technologies, which use silicone heating pads to produce heat to warm up the battery cell. The heating pads consist of resistance wires, heat-conducting silica gel cloth, and silicone lines, all of which comply with ROHS requirements, standards set to constraint the use of materials that are harmful to the human body as well as the environment.
How Renogy’s battery survives this test: below five Celsius degree, Renogy’s battery can still get charged because when it is plugged in and with the rated DC voltage running through, the heating pads is able to generate heat. And the Li-ion cells will get warm enough to function as usual. But once the heating temperature hits 10 Celsius degree, the heating function will stop automatically so as not to harm the battery.
With this self-heating edge, Renogy battery can always work under -7°C.
Test #3: 1.2 m Drop testing
In this test, we conduct a battery cell test and a full battery pack test. The tests will allow us to estimate their impact resistance during transportation and handling as well as when accidental drops happen.
The dropping tests include:
One corner drop: upon dropping, the sample corner hits the ground;
Three edge drops: tilt the bottom surface of the sample at a horizontal angle of 20°, and raise it to the specified height and release it; upon dropping, the sample edge hits the ground;
Six face drops: When released at the height of 1.2 m, the face of the sample hits the ground.
Here are the performance statistics of the tested battery:
Data before and after the tests
The stats show that the performance of the battery remains excellent even after the drop test.
Also, the drop tests show that both the battery cell and the battery are safe without liquid leakage, blasts or fire, which complies with the UN38.3 standard.
Test #4: Puncture testing
So far, there are more than 300 methods for testing the safety of batteries. The puncture test remains the harshest and most difficult one to tackle for battery manufacturers. Only extremely high-quality batteries can pass this strict test. Therefore, some unreliable manufacturers may try to dodge the dangerous test.
The test employs a probe to compress the battery cell until it ruptures. During the process, the battery will experience a thermal runaway, and that is when we can observe how the runaway develops.
About battery thermal runaway: it means that during internal chemical reactions, the heat generation speed is much faster than the heat dissipation speed. With too much heat accumulated, the battery can quickly collapse and lead to fire or blasts.
In this test, Renogy’s battery, again, shows extraordinary qualities.
Let’s show you the test with more details:
1.Before the test, the battery will be fully charged.
2. The probe is high-temperature-resistant, smooth and clean without rust, oxide layer or oil stain. And it measuresφ5mm-φ8mm.
3. The probe will penetrate the geometric center of the Li-ion cell vertically at a speed of (25±5) mm per second.
4. The probe will be left stayed in the ruptured battery for one hour.
As we can observe, the tested battery is safe without liquid leakage, fire, and blasts.
Note: the test simulates the harshest condition a lithium battery can encounter so that we can predict what will the safety risks a battery can bring about. But rest assured, those circumstances are rare events. There’s one more thing we can know is that even with the hardest tests, Renogy batteries prove to be safe and reliable, and can handle more challenging situations than other batteries.
The safest lithium batteries from Renogy
Now that you mgiht have an answer for "Are lifepo4 batteries safe", it's time for you to pick a safe lithium battery for your solar installations from a reliable brand. Renogy has invested numerous efforts in the research and development of solar battery management systems, and that’s why now we’ve possessed many core technological patents. As you can find on our websites, we’ve developed our own integrated intelligent battery management system (BMS), DC home app, Renogy One, as well as the REGO system, all can precisely monitor irregular battery conditions and activate protections automatically.
For example, our battery management system incorporates functions like:
Overcurrent protection: presume that a battery has a rated maximum discharge current of 100A, and when the current exceeds 130A, the BMS will automatically disconnect the load within one minute. But once the discharge current exceeds 150A, the load will be automatically disconnected within 300 microseconds.
Over-temperature protection: when the battery discharge temperature surpasses 60 Celsius degree, the BMS will automatically disconnect the load and reconnect it when the temperature drops back to 50 Celsius degree. In addition, when the charging temperature goes over 55 Celsius degree, the over-temperature protection mechanism will restrain the charging until the temperature cools down to 50 Celsius degree.
Overvoltage protection: when the voltage of a single cell exceeds 3.7V, the battery with BMS will automatically enter the protection mode within 0.5 seconds, and continue to work normally when the voltage returns to 3.45V
Undervoltage protection: When the voltage of a single cell drops lower than 2.5V, the battery with BMS will automatically enter the protection mode, and go back to functioning when the voltage returns to 3.1V;
Short-circuit protection: Whenever a short circuit occurs, the mechanism will disconnect the load within 300 microseconds.
If you need to find more information on battery safety monitoring systems, or looking for a 12V lithium battery with a higher safety level, look no further than the lithium batteries supplied by Renogy. We produce the best and most reliable RV batteries for the peace of RV nomads. Renogy will try every effort to allow you to enjoy the convenience of energy storage systems as well as insulate you from safety risks as much as possible.