Power management is key for today’s mobile devices because usability largely depends on autonomy. As an experienced engineering partner of deep-tech companies, Helbling develops and optimizes power management solutions with a particular emphasis on usability. Specialist engineers leverage their particular expertise to design and build prototypes and carry out tests on the basis of cutting-edge lab infrastructures.
Mobile devices and wearables are ubiquitous in consumer electronics and MedTech, for example, as well as in other fields. Users demand ever-increasing autonomy and constant availability of their gadgets. Powering these electronic devices requires profound engineering expertise to achieve optimum usability and performance.
Helbling has developed numerous mobile devices in consumer electronics, MedTech and other industries with a variety of efficient power management solutions. Examples here include wearables ranging from smart watches to electronic spectacles and even smart contact lenses. Whether it is a niche application or a high-volume product, Helbling’s experts approach the task at hand with real clarity.
Three aspects of power management determine autonomy
One of the keys to maximizing usability is to increase device autonomy. This requires power management aspects to be carefully considered during the development process. In the engineering world, power management of mobile devices can be broken down into 3 pillars:
- software design for low power consumption
- usage of low power electronics
- selection of the appropriate energy source
Each of these three aspects are important when developing a mobile device. The software design can ensure that low power configurations and sleep modes are effectively used. The component selection and electronics design should minimize leakage currents and provide certain functionalities such as a charging circuit for safe and quick re-charging, fuel gauge for assessing the remaining energy, voltage converters for generating the appropriate system voltages, and a protection circuit for ensuring the safety of the energy source.
Power management stands and falls on the selection of the energy source
A previous specialist article dealt in detail with energy harvesting approaches for mobile devices. However, the focus of this present article is on the energy source. Unless the device is operating in passive mode, an energy source will be required to operate independently from the mains power supply. Today, the pre-dominant battery technology relies on re-chargeable Li-Ion or Li-Po batteries, although niche applications with NiMh batteries or supercapacitors do exist. Li-Ion batteries are a preferred choice because of their comparatively high energy density.
The starting point for the selection of the energy source is a power budget based on a typical use case and other constraints. This will help to specify key requirements for the battery, e.g. its capacity. Mechanical integration aspects will constrain the mechanical size of the battery. When there are strong constraints on the mechanical size of the battery, customization is common and usually possible at moderate costs. In all cases, it is important to remember that batteries are subject to breathing or swelling over their lifetime, therefore the mechanical integration of a battery must account for such dimensional variations. From the application use case, secondary requirements for the battery can be derived, e.g. maximum charge current and discharge current (known as the C-rate) and the cycle life. Finally, constraints imposed by environmental conditions such as temperature or humidity must not be overlooked.
Safety considerations may make it necessary to investigate alternatives to the standard Li-Ion technology which has a liquid electrolyte. Solid state batteries are an emerging technology that boast a better safety profile due to their solid electrolyte. Especially in the field of micro-batteries they offer additional advantages such as small dimensions, high energy density and long cycle life.
Testing is key to ensuring reliability and safety, whereby all batteries must be tested according to applicable norms and standards. This is carried out at accredited test labs, which issue the test report. For safety-critical (e.g. MedTech) applications, manufacturers should insist on the CB certificate in addition to the test report as an internationally recognized mark of conformity for electrical and electronic products. Aside from normative testing, it is advisable to perform lifecycle testing for the envisioned use case, so that the datasheet values can be put through their paces under real life conditions.
How Helbling’s power management expertise leads to the development of efficient mobile devices
Helbling has amassed comprehensive experience in the development of mobile devices in consumer electronics, MedTech and other industries with different energy sources, including primary and secondary batteries, as well as supercapacitors. In specific terms, these activities encompassed both standard Li-Ion battery technologies and advanced solid-state batteries, which have been integrated into standard handheld devices, wearables such as smartwatches or electronic spectacles. Micro-batteries have even been used in electronic contact lenses and implantable intra-ocular lenses.
In addition to the team’s experience and expertise, a key success factor is Helbling’s lab infrastructure. This includes a battery tester for performing accelerated lifecycle testing, whereby multiple batteries can be examined at the same time and in accordance with a defined use case.
For example, in previous projects these battery tests have already allowed critical performance changes in batteries to be identified depending on the ambient temperature or discharge current. As a result, it has been possible to resolve such issues early in the development process. In practice, pre-selected batteries were tested in a fireproof environment under different conditions including temperatures from -20°C to 60°C and discharge currents from 0.1C to 10C. These tests allowed the team to identify the best battery candidate in terms of fulfilling performance, lifetime and safety requirements.
Summary: Autonomy of mobile devices for best-in-class performance is achieved through engineering excellence
It is only when mobile devices and wearables offer genuinely convincing autonomy that they become firm fixtures in the daily routines of users. To this end, the trifecta of software design for low power consumption, usage of low power electronics and selection of the appropriate energy source must be optimized in relation to the design, implementation and testing of smart solutions for power management of portable devices. In all three areas, Helbling brings to the table its expertise for the benefit of its customers, and in so doing facilitates the development of pioneering, future-proof mobile devices.
Authors: Mathieu Jeckelmann, Stefan Bauer
Main Image: Gemini
