52 September/October 2025 | E-Mobility Engineering the thermal management system must remove, in turn reducing the amount of energy it consumes. The second category of successfully electrified mining vehicle is underground haul trucks. These typically carry payloads of 20 to 100 t and feature either pure BEV or trolley-assisted BEV hybrid powerplants. The Sandvik TH665B, for example, can carry up to 65 t up a ramp with a 1:7 incline at 9.6 kph, which is up to 25% faster than a conventional diesel truck, according to Sandvik. It’s LFP battery pack feeds a powertrain that delivers 630 kW of continuous power, and can be changed in around 3 minutes using the company’s AutoSwap selfswapping battery system. When the battery needs changing, the vehicle positions itself over the AutoSwap station, aligning itself with accuracy of +/- 10 mm using a guidance system based on Lidar and camera sensors. The exhausted pack unlocks from the chassis, with both high-voltage connectors and liquid-cooling lines disengaging automatically. Next, the robotic lift mechanism, which can handle packs weighing up to 5 t, lowers the pack onto a transfer cart, while a fully charged replacement is moved into position ready for installation. When the replacement is lifted into place, the high-voltage contacts and coolant lines reconnect automatically. Finally, the vehicle’s onboard system verifies the battery’s health, voltage and cooling system status before the vehicle resumes operation. Conventional fast charging of packs with capacities up to 500 kWh takes much longer at 1 to 2 hours, typically. Fast charging tends to be harder on batteries than the slow charging used in battery swapping systems, but swapping needs more batteries in the inventory to accommodate the extra charging time. Trolley time Epiroc’s battery electric Minetruck MT42 SG, in conjunction with ABB’s eMine Trolley System, represents an alternative approach, using a pantograph to draw power from an overhead catenary along inclined sections of the underground haul route where power demand is highest. In operation, when the truck approaches the trolley zone, sensors align the pantograph with the overhead line, then the arm lifts and locks onto the wire, a process that can be automatic or initiated by the driver. The system has been demonstrated in a cooperative project between Epiroc, ABB and Swedish mining company Boliden on a purpose-built 800 m underground test track with a 13% incline in the Kristineberg mine in northern Sweden. The installation aboard the truck includes a DC-DC converter from ABB, and enhances the driveline with HES880 traction inverters and more powerful AMXE motors, while Epiroc added dynamic charging capability to the truck and its battery system. ABB was also responsible for the infrastructure, including the rectifier substation for the test track, and the distributed control system. The MT42 SG is an articulated truck that can carry up to 42 t, equipped as standard with a 465 kWh liquidcooled battery pack – made up of five sub packs – that operates at 800 V using cells based on NMC chemistry and featuring an integrated thermal management system. The vehicle articulates in the centre, with the front and rear halves each having its own axle driven by its own battery, traction inverter and motor, with no mechanical link between them. Common in articulated mining vehicles from various manufacturers, this type of configuration presents a power distribution challenge to vehicle developers, who need to work out the right amount of power to send to each axle at the right time to ensure the ability to climb and descend slopes and negotiate tight turns. Sandvik, for example, has patented an approach to this that relies on the vehicle having a battery pack dedicated to each axle. The power distribution system (PDS) compares the state of charge (SoC) of the two packs and seeks to balance them. It assumes that when the vehicle is under load, the pack with the higher SoC needs to deliver more power and it then commands its inverter to send more power to its motor and, optionally, to reduce the power from the other pack to its own motor. During regenerative braking, the PDS charges the pack with the lower SoC to equalise charge levels. LFP, NMC and NTO There is a mix of battery chemistries in use aboard mining vehicles including LFP, NMC and LTO, with new technologies such as Skeleton’s SuperBattery (a sort of battery/supercapacitor hybrid), sodium-ion and solid-state batteries under consideration. Insight | Mining electrification With a swappable LFP battery pack and a 65 t maximum payload, Sandvik’s 630 kW TH665B underground haul truck is faster than diesel equivalents up steep inclines (Image courtesy of Sandvik)
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