Anyone here already achieved DIY battery-free sensor ? Sharing experience - Page 1
Forum section: electronics / beginners

author: JL34
author_rank: Contributor
timestamp: December 25, 2020, 11:13:01 am
content: Hello,I am interested in the field of the IoT for my own usage. Especially in Green Powered Devices and battery-free sensors. I'm thinking about design and deploy a battery-free indoor sensor grid in my house, with Zigbee Green Power protocol. At least trying to. Even in case of fail, it could be a knowledge enriching project.Anyone has already achieved this kind of sensors ?What brand/model of ultra low power chip did you use ?What source of energy did you use ? RF ? Light ?Why did you those choices ? Could you tell us more about ?Thanks for sharing your experience

author: tszaboo
author_rank: Super Contributor
timestamp: December 25, 2020, 01:07:04 pm
content: You want something that runs from low voltage, and has a built in DC-DC. Silicon labs blue gecko for example. Set the power output below or at 0dBm, then it uses about 5mA while transmitting, calculate the energy requirement for that. Double it. Monocrystalline solar panel, the rest is garbage for this.Dont expect messages too often, and range is not great. You also have to match the antenna, that's probably the largest gain (pun intended) in the design.When you are finished, and placed a supercapacitor on it, you can realize that the entire concept of the device is pointless, because you could run it from a primary lithium battery for a decade. And your supercapacitor has a limited lifetime, it's internal leakage increases with it's lifetime.

author: JL34
author_rank: Contributor
timestamp: December 25, 2020, 01:20:30 pm
content: Thanks for your answer.I have already ordered a Silicon Labs Gecko starter kit (SLWSTK6021A) to do some experiments.I know that could run for a decade on a lithium battery. But I am curious how battery-free devices work. Some are designed to have a very long lifetime, not limited by a super capacitor nor lithium battery.How do they harvest and store energy ?

author: DTJ
author_rank: Super Contributor
timestamp: December 25, 2020, 02:14:38 pm
content: Quote from: JL34 on December 25, 2020, 01:20:30 pmWhat is your environment?PV solar.Mechanical - vibration generator, piezo powered.Thermal - Peltier powered.

author: JL34
author_rank: Contributor
timestamp: December 25, 2020, 02:20:47 pm
content: > What is your environment?Standard indoor environment. Lighted during the day, in dark the night. With a Wi-Fi network. No mechanical energy available in most case.What are the possibilities in this case, apart RF and light energy ?And more generally, how it is achieved in others environments, like those with battery-free sensor grid deployed ?

author: tszaboo
author_rank: Super Contributor
timestamp: December 25, 2020, 10:33:53 pm
content: Quote from: JL34 on December 25, 2020, 01:20:30 pmGood starting point.Here is an application note for you, it explains more:https://www.silabs.com/documents/public/application-notes/AN0061.pdfAnd some more on how to do this:https://www.silabs.com/community/mcu/32-bit/knowledge-base.entry.html/2014/06/18/energy_harvestingso-MuUY

author: Benta
author_rank: Super Contributor
timestamp: December 25, 2020, 11:22:43 pm
content: This might interest you:http://www.micropelt.com/en.htmlThermal energy harvesting using the Seebeck effect (not Peltier, that's the opposite).No affiliation.

author: DrG
author_rank: Super Contributor
timestamp: December 26, 2020, 12:37:43 am
content: I have used these products with indoor lighting and they do work.https://www.cypress.com/documentation/development-kitsboards/cyalkit-e02-solar-powered-ble-sensor-beacon-reference-designHere is some info on the energy harvesting chip.https://www.cypress.com/products/s6ae10xa-solar-optimized-energy-harvesting-pmicMight be interesting for you to check out.

author: JL34
author_rank: Contributor
timestamp: December 26, 2020, 09:18:45 am
content: Thanks for your replies. Very interesting readings.I see better the different existing energy source for those type of devices.It seems to me that it is not possible to achieve a battery-free device that be able to run daily (day and night) all the year in a home indoor environment : light energy is available only when sun is raised or lights on, and thermoelectric energy are available only when heaters are on (so only in cold season).A tiny rechargeable battery should be integrated, but what are the type that have the longer lifetime ?What about storing energy in a non-wearing capacitor like a ceramic capacitor ?Edit :I have created an other topic for the battery selection :https://www.eevblog.com/forum/beginners/need-advices-on-suitable-battery-type-with-high-lifetime-for-iot-devices/

author: ElektroHS
author_rank: Contributor
timestamp: March 16, 2021, 12:44:29 pm
content: I thought about similar question how to minimise power of devices... but battery-free / supercapacitor-free / and similar for small sensors - it's very hard to achieve at the moment imho.As minimum solar panel will take some size... and you need to keep energy for night/dark time... but this theme has good potential for future....