2 Replies Latest reply on Jan 3, 2016 6:42 AM by HeLi_263931

    Energy Harvesting - can a LiPo battery be used as the energy storage device?

      First of all I am not sure where Energy Harvesting topics are supposed to be posted...


      Santa brought me the S6SAE101A00SA1002 Solar Powered IoT Device kit and I have started to work with it.


      In my application my IoT sensor is measuring current 8 x a second over a 3 or 4 minute period. After the process is finished the AmpHr data is sent out via BLE. The IoT will be mounted to a conveyor and so batteries are not an option. It takes the conveyor 30 minutes to make one cycle. It seems that vibrational energy could be harvested over the entire 30 minute cycle and stored up for use in the 3 or 4 minutes when the IoT is measuring and storing data.


      Is it possible for the EH chip to charge up a small, single cell LiPo battery? Or is a capacitor the smarter way to go? I can see a situation where the conveyor is turned off at the end of the shift and then restarted in the morning. There has to be something left over 'in the tank' for the first couple of units as they have been idle and not generating any energy before the conveyor is restarted.

        • 1. Re: Energy Harvesting - can a LiPo battery be used as the energy storage device?

          Charging a LiPo is quite a complex procedure that requires some additional hardware and a controlling micro (which you have got). Energy losses are comparably high, so this method will be recommended, when the amount of harvested energy is high, Charging a gold cap (protection circuits!!!!) could be a good alternative with a minimum of effort. Try first with the recommended 220µF cap to see what happens.





          • 2. Re: Energy Harvesting - can a LiPo battery be used as the energy storage device?

            You need to calculate your energy budget. How much energy to you need to the measurement, how much for the BLE transfer, and how much energy can you generate by the harvesting?


            Small LiPo cells (in the 100mAh range) can be charged by quite low currents (down to 1mA even). The LTC4071 can do this quite efficiently (its a shunt regulator, so its not wasting energy during charge). Or you configure your energy harvesting so it doesn't output more than 4.1V, then you don't need a regulator (did this before, works quite well). LiPo batteries are not as efficient as capacitors, but they store much more energy.

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