E-Mobility Engineering 017 l ECE Doosan electric excavators dossier l In Conversation: Matt Faulks l Battery testing focus l Battery Show North America 2022 report l Ariel Hipercar digest l Cathode materials insight l Thermal management focus

Dossier | ECE electric Doosan DX165W and DX300LC these heating and cooling components minimises parasitic losses from thermal management. Vehicle Interface Box The BMS is housed in Webasto’s Vehicle Interface Box (VIB), which uses an automotive controller for functions relating to battery management as well as sharing key performance and health information with the vehicle control unit and ECE’s fleet management systems. It is also contained in an IP65-rated enclosure for ruggedness in the harsh construction yard environments. The VIB tracks and manages battery temperatures, with sensors taking readings at 32 positions per pack, shutting off the packs if excess cold or heat is detected. It also balances power and energy across the cells, using Webasto’s Vehicle Gateway, the BMS software package provided as standard with the VIB. Also inside the BMS is a range of safety hardware features, including circuit breakers, overcurrent protectors and pre-charge resistors. Cabin systems Van Hal comments that the 800 V architecture was not only important for the PowerBoxes and e-motor, it has also had a significant impact on the development of the HVAC system. That’s because ECE wanted to use an 800 V compressor for the HVAC in the excavators’ cabins to minimise the part count and energy inefficiency of using a lower-voltage system with a DC-DC converter. “Two years ago it was still very difficult to find 800 V air conditioner compressors, so at the moment our active excavators are using 24 V compressors with DC-DCs for the air conditioning, as well as the original HVAC interface panels as on the fuel- powered DX165W and DX300LC,” Van Hal says. “That’s a different 24 V DC-DC to the one connecting to the cabin systems battery,” he adds. “That battery was also used on the original Doosan machines to provide a stable low- voltage power output of up to 3 kW – more than enough for the operator’s panels, lighting systems, controllers and connectivity systems. “But if we’d added the compressor alongside all those systems it would have brought us close to the discharge limit of that small pack. That’s why the compressor has its own dedicated converter and pack, identical to those of the operator systems.” And while the fuel-powered excavators would use the heat intermittent, sharp spikes in the loads on the batteries, and without cell technology formulated with high power discharges in mind, either the EVs’ lifting capabilities or the lifespans of the cells (or both) would suffer. Each pack therefore contains 16 SDI modules, connected together for 400 V per pack, hence the 800 V output per PowerBox, when two pairs of packs are connected in series. Battery thermal management While the packs contain these modules, also inside the main housing of each pack are two plates for water- glycol thermal management circuits for combined heating and cooling. The plates are integrated as standard with each pack, as it is widely known that lithium-ion batteries are at their safest and most efficient when operating in environments of 25-30 ºC, a temperature range that is particularly challenging for ECE’s northern European customers to offer easily. The plates are therefore installed in the tops and bottoms of the modules and cells of each pack, and when installed in the PowerBox they conduct heat to and from an onboard heating circuit as well as a refrigerant circuit. The heat circuit uses an 800 V heater combined with a heating pump, while the cooling loop uses 800 V e-compressors with a radiator for cooling. The high-voltage design of Some key suppliers Battery packs: Webasto Battery modules: Samsung SDI Active thermal management systems: Webasto BMS: Webasto Onboard charger: Stercom Motors: Danfoss Inverters: Danfoss Hydraulics: Bosch Rexroth Axle: ZF Fast DC charging at 150 kW as well as AC charging at 44 kW are available 26 January/February 2023 | E-Mobility Engineering