26 valued in preventing fire propagation if a cell goes into thermal runaway. GCK Battery has run C-Rate tests of its immersion-cooled 12s16p module (one without any flow or radiator) against two other types: one with a single, standard cooling plate and one with dual cooling plates (both were 12s24p systems with higher power throughput than the immersion-cooled module for the same C-Rate). While the three performed similarly at C-Rates of 1 to 2, considerable thermal differentials emerge exponentially as they were charged at higher rates. At a C-Rate of 8, the immersion-cooled module held at 50 C, while the dualplate module reached 106 C and the single-plate hit 163 C. At a C-Rate of 10, the immersion-cooled system reached a maintainable 65 C, and the dual-plate unit went up to 140 C. The mono-plate product had surpassed 200 C at a C-Rate of about 8.4, and could not be safely run up to the target C-Rate of 10. Battery management The first function of the BMS is to monitor and prevent abuse conditions such as over-temperature conditions, overcurrents, short circuits and so on. It also constantly calculates the SoC, state of health (SoH) and C-Rate of the pack, such that all this information and its subcategory parameters can be reported to the driver in real time. “The BMS connects to a PDU [power distribution unit] outside the pack. The PDU is a box composed of many electromechanical components, allowing the control, and cutting off, of power from the pack to the inverter and motor when necessary,” Santiano says. “We install dual PDUs in the snow groomer, and we also split the pack into two halves of modules, so that if there’s a problem with one half we can still run on the other to drive to a safe place to diagnose the problem.” Hence, the BMS executes and automates safety functions, such as closing the contactors to the pack and controlling the flow rate of dielectric oil. Electric motor development Developing a powertrain that can satisfy both the hydraulic and traction needs of the snow groomer brought considerable specific requirements in terms of the compactness (diameter and length), continuous performance, and cost that the motor and inverter need to satisfy. At first, the project partners explored COTS options for their electric drive systems, but could not find a motor that reasonably matched the performance and physical parameters targeted. That led to the decision to develop a new e-motor that would match the specifications. Dossier | H2D2 snow groomer The immersion cooling system used in the pack was co-developed between GCK Battery and Motul (Image courtesy of Groupe GCK) The electric motor has been engineered to perform consistently in temperatures from -25 C to 50 C, and at altitudes up to 4000 m (Image courtesy of IFPEN) May/June 2024 | E-Mobility Engineering
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