By analysing data from 12 000 randomly selected mobile machines, mainly excavators and telescopic handlers, a study from the University of Warwick showed that during the life of a machine more than 32-40% of the time is spent idling. The result is that over 17% of the total fuel consumed will be used at zero productivity.
A cost-efficient way to address this problem is for the machine manufacturers to implement start-stop functionality just like we find in cars . But most of the engine power in cars is spent for its acceleration. However, in construction machinery the engine power is not only used for propulsion but also to power the on-board hydraulics and auxiliary systems. Short and repeatable working cycles are common in construction machinery, and with continuous dynamic changes its difficult to implement a traditional start-stop technology.
The use of intelligent mild-hybrid technology can however be a solution to this challenge. Mild-hybrid technology enables instantaneous start and rapid acceleration using the high torque of an electric motor to assist the engine as soon as there is a need for power. By adding a clutch between the engine and the electric motor the machine can also be powered fully electric with the combustion engine turned off. It has been shown that a start-stop/mild hybrid construction machine has the potential to save more than 10% in fuel consumption compared to a traditional machine, hence the running cost and emissions can be drastically lowered.
By turning off the engine when it’s not used also reduces the strain on humans from noise and vibrations. This leads to less fatigue and an overall more pleasant work environment for the operator, colleagues, and bystanders.