At about 11:00 a.m. on July 18, near the Yuhuangshan Mountain Villa in Hangzhou, an electric car suddenly caught fire during the driving process, and the father and daughter on the car were seriously burned, and the wife of the man on the back walk was also burned in the process of fighting.
From the surveillance video, it can be seen that the electric car from the smoke to the fire speed is very fast, even before it is too late to escape has been burned by the flames, the little girl's mother is also injured in the rescue, the injured were sent to the emergency room of the Second Hospital of Zhejiang University, of which the little girl was the most seriously injured, the situation is heart-wrenching.
The fire rate is very blocky, almost deflagration
Spontaneous combustion of electric vehicles: what exactly is the battery, why is it so powerful?
According to witnesses at the scene, at that time heard a loud noise, and then immediately saw the fire, when he heard the noise has seen an electric bicycle fell on the side of the road, the flames have been raised very high, his job is security, there is a standing fire extinguisher in the room, picked up and rushed over, the fire extinguisher was not able to extinguish the flame for a while, the staff of The Jade Emperor Mountain Villa also rushed to join the fire extinguishing ranks with the fire extinguisher, and when the fire truck arrived, the fire was basically extinguished.
The on-site electric vehicle has been burned into a skeleton, and it is difficult to judge the battery category according to the model, but there are two main types of general electric vehicle batteries, one is the common lead-acid battery, and the other is the lithium battery.
Lead-acid batteries since the invention of more than 150 years ago, the application is very extensive, the two most common uses are car starting batteries and electric bicycle power batteries, of course, the computer industry ups use lead-acid batteries are also very common, and our daily contact is also the most frequent lead-acid batteries.
Computer room ups batteries
But is it possible for it to burn and explode?
Theoretically, there is also a direct short circuit to the battery, then a large amount of energy of the battery will be consumed inside the resistance, which will cause the electrolyte to boil, expand, and the battery to burst, so the charging time is too long The lead-acid battery will bulge is the reason, because the electrochemical process of charging and the loss will produce a lot of heat, if the long-term float charge will appear bulge, so it is best to install a charging timing device.
But the electrolyte of the lead-acid battery is dilute sulfuric acid, in addition to the possibility of burning human skin, it is not flammable and explosive, so it may cause a fire, such as the combustion of the non-flame retardant shell of the electric vehicle, but it will not actively burn, and the spread speed after the fire is not so fast, from the perspective of the fire speed, it can basically be ruled out that it is a lead-acid battery.
Another suspect is lithium battery, the general popular lithium battery has two kinds, one is a ternary battery, the other is lithium iron phosphate battery, the latter is byd more respected battery, the former is Tesla's pursuit, in terms of energy density, ternary lithium battery is much higher than lithium iron phosphate, according to anecdotal estimates, almost 1.5 times, and ternary lithium battery at low temperatures also perform much better than lithium phosphate.
But ternary lithium battery has a fatal problem, that is, the risk of overheating explosion combustion, the difference between the two batteries is the difference in the cathode material, lithium iron phosphate battery is to use lithium iron phosphate as the positive electrode, ternary lithium battery is also called ternary polymer lithium battery, mainly by nickel cobalt aluminum or nickel cobalt manganese as the positive electrode.
The so-called ternary of ternary lithium battery is nickel salt, cobalt salt, manganese salt, the proportion of nickel cobalt manganese can be slightly adjusted according to actual needs, the reason why it is unsafe is because these metal salts will decompose at a certain temperature, the chemical reaction of ternary lithium material is more intense, it will release the combustion of oxygen molecules, and the electrolyte will burn rapidly under the action of high temperature, so that it not only becomes a source of fire and the oxygen generated by the reaction is also ignited, which becomes a "flamethrower", so the fire combustion of ternary lithium battery is very violent.
And the summer is the high temperature season, the temperature in the environment of 35 degrees Celsius, the temperature near the road surface can reach more than 60 degrees Celsius, and electric vehicles and electric bicycles are parked on the road, and even may experience exposure, the temperature itself is already very high, and then let it output power, that working condition is really very bad!
Ternary lithium battery bursts after puncture
In addition, most lithium batteries use 18650 battery packs, which are composed of n-cell batteries, circuit boards that prevent overcharge, over-discharge and balance batteries, electric vehicle batteries and thermal management systems, of course, electric bicycles are unlikely to have this equipment. Equipped with regular manufacturers of lithium batteries are fine, if those three no products or unpacking batteries, the quality is more difficult to guarantee.
In addition, there are also a lot of modified lithium batteries on the Internet, that is, blue thermoplastic package, the planter has also changed the lithium battery, know how much risk this thing has, so it is really afraid to change it, the small electric donkey at home is still honest and practical lead-acid battery, after all, that thing is short-circuit and not too dangerous, at most it is a smoke, and then slowly burn up, at least there is time to run.
Now the new community has no garage, there is no overhead layer, only parking spaces and electric vehicles, some residents are reluctant to charge that little money, like to push the electric car over the elevator back to their own home to charge, of course, the other is also afraid of theft, so there was a chengdu Chenghua District a battery car in the elevator explosion incident, fire instant elevator door closed, really human purgatory, really can't bear to look again, there are mothers holding 5 months old baby, it is too heart-wrenching.
Lithium battery battery car, obvious endurance distance is much farther, for high capacity and low cost, generally are ternary lithium battery, into the above mentioned, there are various risks, of course, lithium iron phosphate also has risks, not ordinary people can modify, do not know the blind toss, the most secure is lead-acid battery, but the endurance will be worse, but no matter which, you choose regular manufacturers products, do not try to cheap and save trouble modification or choose three no products.