Saving the IoT from drowning us in dead batteries

IoT : A Huge Market

These days, a lot of press in the electronic industry is dedicated to the Internet of Things (IoT), wearable electronics and a trend to an Internet of Everything (IoE). While I think that some marketing folks are having a blast continuously re-branding the technology progress in miniaturization and integration, there is definitely the potential for a massive influx of devices that will augment the Internet with their data and expand the functionality of common objects. The potential efficiency gains from all this new data can bring significant benefits.

A few weeks ago, I got an interesting link from a colleague about projected numbers related to the Internet-of-Things entitled Mind Blowing Stats on IoT. Like many recent statistics about IoT potential, it highlight the massive scale of the resulting system.

As designers of those future devices, we need to juggle with the data security models, device authentication, secure firmware updates and other issues related to the scaling of system complexity. One thing that is not too much talked about is how we will power all those devices.

Many Batteries

Image credits: Environment Canada1

The selection of the proper power source for those smart objects will come in as one of the top consideration. Adding a few billion devices that each require a battery2 will drive demand (a good thing for battery makers), but will have environmental and system-level consequences that should be seriously considered.

Cost and Environmental Impacts

It will become a hassle to have our latest smart objects becoming dumb when their batteries is depleted, especially if they become ubiquitous and we forgot about them.

The battery replacement cost can also become significant3. For example, a company designing a smart locator tag may select a non-rechargeable primary coin cell since the resulting circuit is simple and low-cost. If the tag is built from low-leakage components with attention to firmware idle current draw, one can expect approximately a year of operation from that coin cell. If the locator has a 7 year life, then the owner will go through 6 more cells with an estimated total cost of around 18$. That cost in battery replacement alone is almost the cost of the locator tag itself, but not apparent at the time of purchase.

Successful IoT objects will result in smart offsprings such as other asset locators, distributed sensors for other physical monitoring (think of water leak detectors, temperature alarms for you pet hamster and so on). Considering that a billion or so buyers on the planet can currently afford and use this technology in the short term and a few billion emerging market consumers will add themselves to the list, the battery consumption will be staggering. Locators are one example of smart objects that fortunately do not use draw that much power from a battery. Smart clothing and wearable electronics tend to require significantly more as they carry more sensors and users like to have a constant interaction with their devices.

Designers of those systems collectively need to ensure we make the best possible system-level decisions to alleviate the environmental impact of this large-scale deployment.

Go for Efficiency

A lot can be done to make the future generations of IoT objects more efficient. Semiconductor vendors build ever more efficient radios and processors, so selecting the right device is a good start in making an efficient product. Even with the most care in the selection of the best ICs, the code (firmware) that is developed will have the most impact on the energy usage. With standby currents measured in nanoamperes, leaving one of the many peripherals on the IC active during standby periods (an easy mistake) can reduce the battery life by many months. A good power management is essential to leverage the low-standby current of modern devices.

Assistance from Fusion Power

http://www.ixys.com/productportfolio/greenenergy.aspx

http://www.micromanufacturing.com/content/micro-technology-powers-low-cost-solar-energy

Current IoT system-on-chip radios are already amazingly efficient in their use of energy. Based on the minute power requirements to keep some of those devices active, it would only need a tiny amount of energy trickling in to keep it running for its useful lifetime. Considering that we own an amazing nuclear fusion generator located approximately 150 million km away and holding our planet in orbit, those IoT devices could leverage a bit of that free energy to save our environment.

It is now possible to obtain tiny solar cells (e.g. IXYS) and energy harvesting chips (e.g. Cypress / ST Microelectronics) that will either supplement or completely replace the battery present in the IoT device. By supplying even a tiny amount of current, but over the very long periods of daylight, those can significantly reduce the average energy drain on the battery and thus extend its lifetime significantly.

Future Work

My hope is that the ongoing research on energy harvesting ICs and tiny solar cells will gain as much interest as the cloud data, services and benefits that the IoT will bring to the economy in added efficiency and convenience. Top semiconductor companies are releasing new crops of energy harvesting IC, which combined with the latest small-scale solar cells will definitely be part of our designer's toolbox. We certainly want to avoid creating an Internet of Everything nightmare where each morning is spent locating objects to replace their dead batteries.


Footnotes

  1. http://www.ec.gc.ca/mercure-mercury/default.asp?lang=Fr&n=8E1CA841-1

  2. Even if a wall-powered IoT device may use little power for its communication needs, the standby power losses integrated over its lifetime may be much higher than anticipated if little care is given to its power supply efficiency and design.

  3. It can range from a dollar or so for a AA battery to more than 3$ in a local convenience store for a disposable cell such as the CR2032 (a very common coin cell).


Motsai designs and builds innovative embedded systems, and is the leading Canadian developer of miniature low-power, wireless devices used in wearables and human motion analysis. Please feel free to send us an email at info@motsai.com or drop us a line at +1-888 -849-6956. Don't forget to signup for blog updates below.

Jean-Samuel Chenard

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