Development of intelligent handle for assistance in vacuum extraction deliveries. : Optimization of low power designs with an experimental investigation of the battery recovery effect.

Abstract: Karolinska Institutet has requested a new version of their measurement device in the form of an intelligent handle to be used in vacuum extraction deliveries at the hospital’s maternity ward. The development of the device has been focused on reducing size, manufacturability, energy optimization and to water proof the device. In the literature reviewing the energy optimization of portable devices, the disputed phenomenon of the battery recovery effect was identified as in interesting research area. The Battery Recovery Effect is based on the knowledge that chemical imbalances arises in certain battery types when subjected to load over longer periods. If the battery is allowed to rest, the chemical compounds are allowed to regain equilibrium increasing the efficiency of the chemical reactions. This implies that utilizing rest periods can increase the available energy of the battery. There are disagreements in academia regarding the existence of the battery recovery effect and few published investigations are based on proper measurements. Therefore this thesis verifies the experimental results by Arora et. al published in 2017 [1] regarding the existence of battery recovery effect. The investigation has been limited to Li-polymer and Ni-MH batteries. The batteries are drained with continuous and intermittent load profiles with varying sleep ratios, sleep periods and currents. The delivered charge and energy of the intermittent loads are compared to those for the continuous. For the specific batteries used in these tests and for the set of loads applied, no battery recovery effect could be identified. Instead a small decrease in both drained energy and delivered charge was observed when deploying intermittent loads. The new proposed handle design drastically reduce both size and weight. The handle is made water proof together with high robustness compared to the previous handle. Several assembly solutions where evaluated and the results indicate that epoxy glue were the best technique. For moving parts, silicone sealing ensures high water resistance while allowing necessary movement.