E-Mobility Engineering 015 l EMotive Scarab off-road truck dossier l In Conversation: Giulio Ornella l Hall effect and magnetic sensors focus l Challenge of batteries for heavy-duty EVs l Alpha Motor Corporation digest l Automated charging insight l HVAC systems focus

Dr Lena Beckmann, head of battery product management at Webasto Group, concurs on matters of standardisation and integration, noting, “Standardised battery packs give the advantage that you don’t need to take the full investment as a customer. “All customers need is a reasonable size of pack to make good use of the installation space and to achieve an appropriate energy density in Wh/kg as well as in costs, that is, €/kWh. Each vehicle has individual requirements of course, but we see similarities between fitting it between the ladder frame, on the roof, in the former IC engine area, or on the side of the vehicle.” Given these variables, it can be challenging to pinpoint what the specifications for the ideal heavy commercial EV pack might be. Akasol for instance suggests that a pack weight of 500-600 kg with a length of up to 2 m, a width from 0.5 to 0.75 m, and a height of 0.3 to 0.4 m is optimal, with a pack voltage range of about 500-800 V maximum, 150- 250 A, and an energy storage of around 500 kWh for powering something such as a solo or articulated bus, or an EV of equivalent weight and duty. Given the often time-critical nature of such vehicles’ use cases, Akasol also aims to implement fast DC charging systems in its future energy systems. The company also typically designs for IP67- or IP6K9K-level protection in its packs for ruggedness against dust and water ingress, with short-term tolerance of temperatures from -30 C to +60 C. Dr Beckmann meanwhile points towards Webasto’s CV Standard Battery System as having been optimised around dimensions of 960 x 687 x 302 mm, for which the group offers its customers different installation options. For instance, it can be modularly connected in series and parallel in groups of up to 10 packs, with an output voltage bus of either 400 or 800 V. Each Webasto CV pack contains 35 kWh, weighs up to 295 kg, and is IP67-rated. Leclanche meanwhile sees packs weighing 260 to 550 kg being strung together for total battery weights of 2000-3300 kg in commercial EVs, targeting 350-500 kWh of energy for 12 m EVs and up to 650 kWh for 18 m trucks (or 100-300 Ah in terms of general energy capacity). At present, these would deliver power over every level of integration, from pack to module and cell. The extent to which each of these will change over the course of the design process also varies. For instance, Mike Ukabam, application engineering manager at Leclanche, notes, “Battery modules account for around 75% of the weight of a battery pack. They are usually of a standardised design and made as light as possible right from the outset, so as not to be modified when being integrated into a pack.” He adds that the customer’s expected integration method is one of the biggest factors affecting the design of the pack housing. “In some cases, the vehicle structure is designed to support the weight of the pack evenly across the underside of the pack; in other cases the pack needs to be self- supported, as it’s attached at only the end plates of the pack. “A pack designed to be installed in the first case can be made lighter, because it is not supporting its own weight, while a pack designed to be supported at the end plates will need to be reinforced and hence will weigh more. And the choice of enclosure material will be dictated primarily by the cost and application.” Ukabam notes in particular that integration requirements will generally drive significant design differences between packs for trucks and those for buses. “Battery packs for trucks are usually fitted between the chassis rails or outside them,” he says. “They will have fewer fixing points compared to a car pack, and will therefore require a more robust construction. The packs will also be subject to higher levels of torsion than car packs. “Battery packs for buses meanwhile are usually roof-mounted or fitted at the rear, and roof-mounted packs can be made to be ‘self-supporting’, which means the pack weight is supported by the vehicle side structure and not the roof itself.” Today’s heavy-duty EV packs most often tend to use cells with graphite anodes and either NMC or LFP cathodes (Courtesy of Leclanche) Autumn 2022 | E-Mobility Engineering 45 ChallengeOf | Batteries for heavy-duty EVs