back to article Solar-powered LoRa IoT node: Nice idea but it won't replace batteries

A Welsh photovoltaics company has developed a solar-powered LoRa sensor node which it hopes will address current concerns about sensor battery life. Established Cardiff firm G24 Power, trading as GCell, has mated its light-to-’leccy tech with the LoRa standard to create what it said is a solar-powered LoRa node which will not …

  1. Duncan Macdonald

    Supercapacitor ?

    A supercapacitor can be recharged hundreds of thousands of times. The energy storage in a supercapacitor is tiny compared to that in a battery but should still suffice to keep a solar powered IoT node alive during the night.

    1. Cynic_999

      Re: Supercapacitor ?

      Supercapacitors have a finite MTBF, max number of cycles and they deteriorate over time just like rechargeable batteries. Capacitors storing voltages under 2V at room temperature have extremely long lifetimes, but if you want to provide 5V in an ambient temperature of 45 deg C, their life can be measured in weeks. http://www.mondragon.edu/en/phs/research/research-teams/electrical-energy/news-folder/workshop/Mondragon%202012_06_22_Gallay.pdf

      1. Francis Boyle Silver badge

        Serious question

        Why not use conventional capacitors? It not like we're talking about large amounts of energy or long cycle times.

  2. John Smith 19 Gold badge
    Unhappy

    The only way to get those kind of lifetimes is to eliminate the battery.

    Sorry but that's the bottom line.

    Your widget (LoRA Low power Radio Association?) runs in sunlight and does an orderly power down when illumination levels fall down.

    Batteries are a real weakness for this stuff, like wireless alarm nodes that have to keep sending out "I'm allright messages" that burn through batteries.

  3. Infernoz Bronze badge
    Meh

    I say BS on no batteries

    I found a LoRa device that runs off 3.6V Li-SOCl2 batteries, which should be easy to charge with a Solar cell.

    1. Martin an gof Silver badge

      Re: I say BS on no batteries

      There must be a battery or some other form of energy storage involved, and I notice that G24 don't actually claim "no battery". On this page they compare two similar devices. The solar one claims a lifespan of 8 years, while the battery-only one claims 5 years, when broadcasting ibeacon information (uses Bluetooth) at 10 times a second. That makes a lot more sense to me. Swap a primary cell Lithium battery for a rechargeable Lithium and with some clever electronics behind the solar panel you can generate some kind of charge, even if that involves charging a capacitor slowly and then dumping it to the battery when there's enough. Extending the life of a product by 60% isn't bad, though I note there's no comparative pricing, and the question remains whether ibeacons will actually still be around in eight years :-)

      Using the technology for other IoT devices is more problematic I think. There isn't really a size constraint on ibeacons, but many IoT devices need to be very small.

      That said, consider the size of the solar panel on solar powered calculators. Ok, they aren't broadcasting, but it's amazing what you can do in dim indoor lighting with a tiny panel...

      M.

      1. Charles 9

        Re: I say BS on no batteries

        Depends on the lighting. Incandescent and perhaps LED lighting, OK, but I've had a flaky history of using them under fluorescent lighting. Might have to do with discrete wavelengths or polarization.

        As for using these in conjunction with rechargeable stuff, it's probably going to depend a lot on the usage case. Mind you, solar collectors are not new tech, so it's mostly a matter of how much power you need and if you have space or location constraints (as in you can't really use them in a constrained or indoor location).

  4. allthecoolshortnamesweretaken

    "... an illumination is as low as 500 lux, lighting levels commonly found in an office or workplace environment."

    Low? 500 lux is the minimum level of illumination you should have at your desk/workplace per ASR A3.4.

  5. Colin Tree

    cynic

    Got an electricity monitor right here on my bench.

    Yesterday opened it up and the batteries had leaked on the pcb.

    Call me cynical, but I see batteries as a way to sell more product, not to mention the flat battery disposal problem.

    Great to see solar powered IoT. I especially like slowing down the processes to suit the power input. There is a particular clock-less processor which would suit this perfectly.

  6. Alan Brown Silver badge

    10,000 cycle lithium batteries exist.

    In the laboratory at least. They have implementation "issues" for traction applications (current availability) but for very low power draw systems that shouldn't be an issue.

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