# Safety Challenges in Battery Swapping Operations of Electric Underground Mining Trucks
## 2 Current Battery Swapping Methods for Underground Electric-Powered Trucks  
Key performance indicators in modern production industries, including underground mining machines, are productivity, efficiency, and operational costs [14]. More recently, these indicators have included low environmental impact, which is becoming more and more relevant [15]. Battery-powered machines are proving to have lower environmental impact and operational costs, due to the elimination of exhaust emissions, lower price of electricity in comparison to diesel fuel and similar. In comparison to IC machines, trade-offs are made in the areas of productivity and efficiency, but the gap is closing with the introduction of Li-ion batteries of higher energy density and shorter charging times [16; 17; 18]. During the previous 7-8 years, the original equipment manufacturers (OEMs) started to supply the battery-powered machines to the underground mines at numerous locations. Recent research on battery-powered machines (BPMs) operating or on trial in underground mines, as published by [PERSON] and [PERSON] [19], indicates that underground BPMs are present on every continent and are supplied by several companies. The most common machines used in underground mining are load-haul-dump machines (LHDs) for loading and trucks for transport, which are almost exclusively supplied by Company 1 and Company 2. For this reason, these two OEMs are most frequently mentioned among the underground BPM fleet. Surprisingly, there are only two instances referring to Caterpillar, and both are for trial purposes. However, LHDs and trucks are still limited by the battery capacity, i.e., with the battery's stored energy available to do the work. This means that BPMs are required to recharge the battery once or several times during a single shift. Recharging the battery is a time-consuming process, measured in hours. Having this in mind, it is not reasonable to pull the truck or LHD out of operation for the period of battery charging. Two major OEMs(Company 1 and Company 2 accepted the solution of replacing discharged batteries with charged ones--so-called \"battery swapping\". With this approach, BPM is immediately available for operation once the charged battery is installed on the machine. Also, this means that neither the BPM nor the discharged battery requires transport to the surface. On the other hand, it should be noted that this approach implies two or more batteries dedicated to one BPM (one installed on the machine--discharging, and one or more in charging stations). It should be mentioned that the concept of battery swapping was originally introduced for electric vehicles in public transport. Such a concept was somewhat successful for passenger cars, particularly small EVs, where some solutions were developed for manually swapping individual modules of the car's battery (EV's battery consists of several modules, which are built out of cells), meaning that the predominant solution for these vehicles is point charging. On the other hand, successful technical solutions for battery swapping are available for the trucks in public transport. This is documented in a study on battery swapping for heavy-duty vehicles, developed by the Swedish National Road and Transport Research Institute (VTI) in 2024 [20]. This study indicates that the advanced solutions are available from Chinese manufacturers, who are currently supplying the third generation of electric trucks with a battery swapping option. Several OEMs have developed a solution in which swapping stations function as pass-through facilities, constructed on the surface area sufficient for unrestricted access and egress and with an unhindered line of sight. Regarding Occupational Health and Safety (OH&S), this study provides a list of applied Chinese laws and regulations and concludes that European countries lag in this technology, both in terms of technical capabilities and administration (legislation and standardisation).