HEALTH & SAfETy


lithiUm-ioN forklift battEriES? Using a lithium-ion battery to power a lift truck has many advantages in the right application, but the requirements to assure lithium-ion batteries are safe for use in potentially explosive atmospheres is not clear. Some manufacturers have placed trucks with lithium-ion batteries into Ex applications but others, including Pyroban do not believe the technology is appropriate at this time. Steve Noakes, managing director of Pyroban and convenor of the EN1755 standards committee, explains the problem.


CoNfUSEd aboUt “atEX” ComPliaNt P


yroban receives a growing number of enquiries for Ex-certified lithium-ion battery options, and for good reason.


Lithium-ion batteries allow opportunity charging, require less maintenance, and offer longer operation between charges, so have proven to be popular in many industries. However, as it stands, for the foreseeable future


Pyroban declines to quote for the ATEX conversion of lithium-ion forklift trucks. Simply, it is not clear what the right level of


safety is for this technology and, as the Ex standards do not appear to cover traction battery applications, one has to question therefore whether they are safe for use in hazardous areas. At present, Ex standards for lithium-ion


batteries applies mainly to small battery packs, not explicitly traction battery capacities. So, there is no clear guidance on what battery conditions should be considered for Zone 2 and Zone 1 areas (normal operation, foreseeable faults) and what Ex protection concepts are appropriate.


CharaCtEriStiCS of lithiUm-ioN battEriES There are various types of lithium-ion batteries using different chemical compositions. Some are more volatile than others and there is a balance between power density and inherent stability (safety). A lithium-ion battery comprises far more


components than a conventional traction battery. Individual cells are connected together to form modules and each module is connected together to form the overall battery package which is overseen by the Battery Management System (BMS). How each element is designed, produced, and tested is key to achieving the right level of Ex safety. Cells are produced in very high volumes by


factories not always owned by the final battery OEM, so one question posed by the EN1755 committee is how the production of this key component can be controlled and verified for Ex applications. Which Ex protection concept is appropriate is


also a fundamental question which does not have a clear position at the moment as it depends on what conditions are included in the normal operation and foreseeable malfunction requirements. Even an Ex d flameproof enclosure may not


be suitable for a lithium-ion battery despite its ruggedness.


Why arE lithiUm-ioN battEriES a riSk for hazardoUS arEaS? Primarily, if lithium-ion batteries become unstable, they could pose a high risk of ignition if not maintained or operated correctly. This would complete the ignition triangle within a potentially explosive atmosphere. This is because lithium-ion batteries:


Are vulnerable to thermal runaway caused by the individual cells breaking down. Lithium- ion cells can overheat under adverse operating / fault conditions which could result in cells catching fire


The degradation of cells generates hydrogen and oxygen which perpetuates the overheating / fire / risk of explosion


As oxygen is produced as a result of the chemical reaction when the cells break down, even if sealed from atmosphere (which would be the usual source of oxygen) oxygen would be available. It is this fact that fuel, oxygen, and a heat source will be produced when the cells fail which is dangerous. All sides of the ignition triangle are complete


Lithium-ion battery fires are also intense and very difficult to put out so a truck on fire may be in the location for hours before it can be extinguished


There is permanent reduction in capacity, and possible overheating, from over-charging and over-current during charging


There is reduction in capacity or even instability from internal breakdown from under-voltage or over-discharge


Unstable battery conditions can occur if the battery is damaged


In other words, all elements in the battery


design, construction, and use are key to assuring stable operation and prevention of a significant ignition source developing.


do battEry maNUfaCtUrErS offEr EX CErtifiEd lithiUm-ioN battEriES for lift trUCkS? The main battery traction manufacturers have resisted producing an Ex lithium-ion battery for lift


64 jULy/AUgUST 2021 | fACTORy&HANDLINgSOLUTIONS


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74