Charging Li Ions With Minimal Energy: A Study on Current Profiles

Charging batteries in cell phones and other small electronic devices, such as battery banks or laptops, has become increasingly common. Volume and charging efficiency are critical in this space because both source and load lose the energy they need and cannot recover. Charging batteries in a way that maximizes their efficiency is, therefore, as important as transferring energy with efficiency. This research investigates the impact of charge-current profiles on energy savings with over 400 charge-discharge experiments performed on two Li-ion batteries. The investigation is the most comprehensive among the state of the art (SoA) and the only one to effectively normalize the battery’s cycle-life effect. Results show that ripple current charging is ineffective in reducing the amount of energy required during the charging process, irrespective of the battery type. Instead, it is recommended to use a dc charge current that is programmed to reduce when extended charge time is available to reduce the energy loss when charging consumer electronics.