Hold car head again and again tesla spreads out again recently on thing, on June 15, ever was in famous United States political drama " wind and cloud of the White House " in the Mary McCormack of Hollywood female star that acts national security adviser is released push say especially, the park of tesla Model S of its husband produces spontaneous combustion when los angeles street, place favour did not produce personal casualty, it is reported, american country carries safe committee (NTSB) had intervened investigation.
From the point of spot picture, the place with more serious on fire of this tesla Model S is bottom, namely the position of batteries group, this matter pushs issue of safety of electric car batteries one piece where the wind and the waves are highest again, so, below what circumstance can the batteries of electric car produce spontaneous combustion?
Medicinal powder hot inadequacy protects invalidation
Battery of 3 yuan of lithium already depended on the character of high energy density to make the first selection of electric car nowadays, before showing account of batteries spontaneous combustion, " dynamoelectric big Ga " the working principle that explains below 3 Yuan Li batteries simply to everybody first, battery of 3 yuan of lithium is to use lithium ion in the job electron of gain and loss and migratory collect those who will achieve electric energy to store and release.
Certain quantity of heat still can produce while battery of 3 yuan of lithium is discharging, unluckily it special " enervated " , working temperature needs to be in - between 20~60 ℃ , if the quantity of heat of generation cannot diffuse in time not to break accumulation, bring about overheat of ministry of cell inter block, with respect to the hidden danger that can generate spontaneous combustion.
If you return the chemical knowledge that did not forget high school place to learn, the should leftest to periodic chart then a few very lively metals still have particular impression one, and lithium metal is among them one of. If the lithium metal that the reaction inside batteries produces is exposed in air, meeting and oxygen produce intense oxidation reaction, produce combustion thereby.
Enter batteries interior to prevent air, car manufacturer is met normally in batteries group outside and in is designed multilayer crust or model film close safeguard, make lithium metal won't be contacted with oxygen and produce combustion. If preventive measure ageing or suffer bump destroy bring about defend invalidation, after metallic lithium and air are contacted on fire of easy out of control.
How do batteries heat runs a system work?
Since battery of 3 yuan of lithium is right working environment requirement is so slashing, nature of electric car manufacturer is met the working environment that try every means gives it an ideal, dynamical cell heat runs a system (BTMS, system of of Management of of Battery Thermal) emerge as the times require.
The system runs in dynamical cell heat in, mix for passive cooling according to the different cent of cooling source active cooling, the means that uses surroundings refrigeration only is passive cooling, assemble in systematic interior, the kind that active component includes aqueduct of evaporator, cooling fluid to wait gives priority to the refrigeration that use formula.
Air refrigeration cost is low
In passive cooling air refrigeration applies most extensive, alleged air is cool, just as its name implies serves as air namely conduct heat medium, let the purpose that air crosses batteries module to cool in order to achieve directly. In addition, efficiency of air nature refrigeration is inferior, accordingly electric car uses compulsive air to cool mostly, the quantity of heat of batteries passes the fan that discharge wind to be taken away compulsively.
The main good point of wind cold pattern has: Structure simple, cost is low, medicinal powder weight of hot model group is relatively lesser, defect depends on heat exchange coefficient is low between its and batteries cliff face, cooling rate is slow.
Liquid refrigeration efficiency is taller
Below general operating mode, use air refrigeration to be able to satisfy a requirement, but fall in high temperature weather or operating mode of high load capacity, liquid refrigeration active cooling means ability reachs batteries group quite medicinal powder hot demand. Want to know, below identical velocity of flow, airy conducts heat rate is far under direct contact fluid.
The liquid cools even if use liquid and air to undertake the quantity of heat that produces batteries series sends heating up exchange, main way decorates cop to be between batteries module or decorate chuck around module, perhaps be enmeshed module in dielectric liquid. If be used between liquid and module,conduct heat the means such as canal, chuck, conduct heat medium can use water, oil to make cryogen wait even. If batteries module is enmeshed in dielectric to conduct heat in the liquid, must use insulation measure to prevent short circuit.
The main good point of liquid cooling means has: With batteries wall heat exchange coefficient is tall between the face, cooling rate fast, volume is minor wait. Defect also clearly -- existence leakage fluid weight of group of likelihood, model is opposite bigger, structure is opposite inconvenience of complex, maintenance.
In addition, battery of 3 yuan of lithium issues discharge efficiency to be able to drop somewhat in microtherm condition, bring about add boat course of development to reduce, because this electric car heat manages a system to still be met normally,supportive batteries heats function, through air conditioning, heat piece or the liquid heats wait for means, it is normal to make sure batteries also can be in below microtherm weather the job inside temperature limits.
Quantity antenatal still requires multinomial test
Be bumped to prevent batteries group to be in and yuan safe hidden danger generates when parts of an apparatus is fatigue, batteries group is being designed and still need to have safe test in manufacturing process. " dynamoelectric big Ga " understanding arrives, the batteries form that manufacturer of domestic mainstream battery designs should pass dip of high temperature baked wheaten cake, extruding, oscillatory, seawater the multinomial test such as concussion of bubble, high low temperature, ability of ninety-nine thousand seven hundred and ninety-one difficult " repairs " of all previous classics Cheng Zhengguo.
1, baked wheaten cake checks
Test of baked wheaten cake is one of most important segment in all tests, batteries group should undertake below the high temperature of blaze " live " challenge.
In this test that has dangerous sex extremely, the national level inside course of study is exterior baked wheaten cake 130 seconds, batteries group not on fire, do not explode.
2, vibration checks
If batteries group assembles quality to close nevertheless, may appear fixed and undesirable, component becomes loose, the circumstance such as crust burst, in the course bumpy road surface bears when vibration, cause the condition of safety precaution invalidation extremely easily. For this, national level still asks to have oscillatory test to dynamical cell.
The shake table that oscillatory test environment bumps by imitate, environment case that provides different environment temperature and imitate fill the module composition of discharge, in oscillatory test link, batteries group needs to be in - 30 ℃ fall to the environmental temperature of 60 ℃ , every second is oscillatory 200, successive and random vibration 21 hours, such but equivalent imitate the circumstance of exhaustion of drive a vehicle of tens of 10 thousand kilometers.
3, acceleration pounds a test
As similar as oscillatory experiment, the rigid structure that pounds test in order to to test batteries form is stable, when its imitate car passes roadblock, the instantaneous jolt concussion to batteries group structure.
Highest acceleration is concussion test equipment commonly 100G. What concept is 100G? When a dynamoelectric bus is bumped for the car of 50 kilometers by speed per hour, the acceleration that batteries series place gets is 30G about, human heart can susceptive is the biggest acceleration is 50G.
4, extruding checks
Batteries group suffers extruding damaged is one of main reasons of the on fire when electric car produces traffic accident, extruding measures the situation that try out is squashed at imitate batteries.
A 2 tons car, bump with the speed travel of 90km/h, its bump force to be controlled in 10 tons. In extruding experiment, bring to bear on to batteries group when 10 tons force, the batteries group case with compound aluminium simple material already appeared to be out of shape apparently, and of the test it is through the standard not on fire, do not explode.
From this, the course is numerous detect test flow, an acceptable batteries team is born eventually, enough of its safety performance is dealt with drive daily operating mode.
Will high temperature of intense heat of summer if He Anquan uses a car,raid the summer?
Although car and battery manufacturer were batteries group to make heavy preventive measure, but we still want security of batteries of great in using a car actually attention, as the arrival of summer, everybody cares particularly to the batteries safety below high temperature environment, " dynamoelectric big Ga " the note that will to everybody introduce the summer to use electric car.
1, pay close attention to the temperature of car batteries group and cooling system
The summer drives need emphasizes the wind that notes cell cold or water-cooling system, if lamp of cooling system breakdown shines, all should get on for maintenance dot to detect repair.
Be like environment of extreme of occurrence high temperature, answer to avoid to undertake car charge as far as possible, wait for batteries thermal drop to undertake again for normal level. Batteries group temperature is like to exceed reasonable temperature in car travel (it is 55 degrees commonly, specific examine car manual please) , the road surface that should seek safety immediately jockeys, flameout cuts off the power, the phone seeks advice from reentry of car after service to be handled all right.
2, seasonable examination maintains beware circuit ageing, short circuit
Although had batteries to heat up the protection that runs a system, but do not prevent circuit ageing, yuan the case of consenescence of parts of an apparatus appears, spontaneous combustion of car of a lot of fuel also is to come from this kind of problem mostly, before accordingly the intense heat of summer comes, do to love car first second examination and maintain most safe.
3, do not use flying line to charge
Suffer from of a lot of consumer cannot be installed charge picket, can from indoor flying line charges, this kind of practice actually breakneck. Above all electric car fills electric power a lot of taller than common electric home appliances In addition, rainwater of climate of our country summer is relatively rich, flying line line is isolated from normally step is wronger, do not have insulation measure even, if encounter precipitation weather,short-circuit easily also on fire. 4, use charge normally picket Fuel car may add inferior oil, electric car is encountered likely also charge inferiorly picket. A lot of privately build charge picket did not detect through the technology mostly, sex of stabilized voltage steady flow is poorer, and without professional the examination is safeguarded, use this kind to charge it is dangerous that picket can cause injury to have on fire even to batteries group, because this is sure to use,detect through the country, of legitimate operation charge picket. The technical course of electric car although not as good as fuel car, but TA also is not paper paste, do not underestimate the security of TA, of course also cannot the security of overmeasure TA. The vehicle of car of new energy resources with broad hope advocate people, much study understands the professional knowledge of respect of a few electric cars, use car of new energy resources surely.
