25 E-Mobility Engineering | September/October 2025 Mack Trucks LR Electric | Dossier to do that, and would we even have the space? Ultimately, the biggest weight component in the chassis is the batteries and the density advantages of NMC chemistry over LFP [lithium iron phosphate] definitely came into the equation to help us get to that target payload.” Regeneration The basic laws of physics and momentum dictate that a vehicle requires more power to get it moving than to keep it moving. So, the stopstart procedure, with its high-torque acceleration and intense regenerative braking, places greater demand on the battery than a normal blend of slow-, medium- and high-speed operation. The greater pack density in the ESS packs adds an even greater challenge from the internal build-up of heat. So, delivering the performance required for a Class 8 application, without overheating the battery, required significant innovation. The system uses a standard coolant but the creativity comes in the vehicle’s active software systems. “Putting kilowatts in or pulling kilowatts out heats up the battery, and this vehicle is doing this constantly for long periods of time,” explains Fotopoulos. “We’ve chosen components that can handle the rising temperatures in this demanding application, and we manage them through basic cooling and our bespoke thermal management system software. “The battery temperatures are maintained and monitored constantly, and the system knows the state of health for each of the cells themselves, as well as for the battery packs as a whole. That allows us to monitor and manage the temperature around those systems accordingly, and the software plays a big part in keeping things at the right level.” The regenerative system has three different modes - high, low and automatic – as well as an overall onoff switch for the system. “The high setting is for later in the route, when you’re running with heavier loads,” explains Fotopoulos. “With more weight onboard, the forces that you are trying to decelerate are greater, so you can handle greater regen. “The high setting gives more regen capability, so you’re getting more kilowatts back into the battery pack, but when the truck is running empty, you would choose to manually select low because without as much weight onboard, the high regen would create quite a hard braking action when you let off the accelerator, and that is not a very pleasant driving experience. “Our auto mode is not, as most people think, to automatically switch between high and low settings, it’s actually a separate mode for highway use. It allows you to coast the vehicle, with regen only coming on when you start pressing the brake pedal before the pneumatic braking starts, and that creates a more pleasant highway driving experience. “Finally, the on-off mode is a safety measure because when its slippery – be it ice, snow or sometimes even rain, depending on the surface you’re driving on – it allows you to turn off the regen and be able to roll down a hill, for example, and keep more control rather than risking the regen coming on and causing you to lose traction.” The software continually monitors vehicle operations, and this enables owners to monitor their use and better understand their specific duty cycles over time. It also enables Mack to evaluate that performance and develop software updates that can fine-tune the vehicle’s performance over the course of time. When the company introduced its newest model, which included the generation three battery, existing customers were offered an upgrade kit to replace the old battery units. This came with a software upgrade to accommodate the dynamics of the newer system, and the promise of a significant upscale in power led to an uptake rate of over 50%. Regenerative braking provides up to 25% of the power on a daily route
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