Charging and Discharging Control System for a Totally Implantable Artificial Heart with Backing up Batteries

Abstract

In this paper, we report charging and discharging control of backing up rechargeable battery inside body for a totally implantable artificial heart. The battery inside body should be safely and quickly charged. We used 2-stage charging method for safely and quickly charging. The rechargeable battery is quickly charged by constant current source until almost fulfilling in the first stage, and then it is charged by trickle charge in the second stage. It is important that we detect the time when recharger is switched from quickly charging to trickle charging. We used to sense-ΔV of the terminal voltage in case of NiCd battery and rate of surface temperature rise of battery in case of Ni-MH for detecting the switching time, respectively. We found that the recharger can be effectively switched from quick to trickle by sensing-ΔV and rate of surface temperature rise of the Ni-MH battery, respectively. We also investigated to sense and integrate charge and discharge current of the battery for switching the recharger. We found that this method is effective for the switching and possible to monitor remainin. genergy of the battery.