A highly efficient solar powered supercapacitor charger with two regulated outputsDesigned by Jasper Sikken, Ships from Netherlands
The AEMSUCA is a 0.8x0.6 inch board for the AEM10941 Solar Harvesting IC from E-peas. It efficiently converts solar panel energy into SUperCApacitor charge, it even works with indoor light. It feat...Read More…
The AEMSUCA is a 0.8x0.6 inch board for the AEM10941 Solar Harvesting IC from E-peas. It efficiently converts solar panel energy into SUperCApacitor charge, it even works with indoor light. It features 3.3V and 1.8V regulated outputs that are enabled when the supercapacitor has sufficient charge, and a low voltage warning that informs the user of impending shutdown when the supercapacitor runs low. It easily integrates in other projects because of the castellated via's, and when soldered onto 0.1' pitch header it fits in a bread board.
I am also selling a similar board that stores it's energy in a Li-ion battery. Check it out here.
I designed it because I took part in the HackadayPrize2018 Power Harvesting challenge with a 1x1 inch Tiny Solar Energy Module and found a lot of interest in selling it. However since most projects have different power demands and people want to choose their own solar panel, I decided to remove the onboard solar cells. In addition I wanted a variant of the board that could charge a pair of supercapacitors.
This board is special because it integrates maximum power tracking, supercapacitor charging and two regulates outputs in a tiny and easy to integrate board. There's is no other board with so little passive components.
Ideal for indoor applications
The AEM10941 harvesting IC is very suitable for indoor applications because it has an ultra low power startup. The boost converter starts at a very low 380 mV input voltage and 3 uW input power. The IC gets most power out of the solar cells by doing MPPT maximum power point tracking every 5 seconds.
What you get
What is the expected supercapacitor charge current?
I have measured charge current using three different solar panels in indoor light (500 lux), outdoors in the shadow, and in full sun (~500W/m^2).
|Solar panel||indoor 500 lux||outdoor shadow||outdoor full sun 500W/m^2|
Indoors (~500 lux) and with the smallest solar cell the storage element is charged at 50uA for 10 hours. Then the application must have an average current of (50uA*10hrs/24hrs) 20uA or less. That's enough for a simple Bluetooth Low Energy beacon or a very simple LoRa application. If that is not enough you need to select a larger solar panel.
Outdoors, in shadow current is 10-20 times larger. And in sun 100 times larger.
As you can see the AEM10941 can charge a supercapacitors from indoor light but indoor light is really only suitable for very low power applications.
Solar cells I have used with this board
Super-capacitors I have used
How long can an application run supercapacitors?
Rule of thumb: When a 1F supercapacitor is loaded with 1A the voltage will drop 1V in 1s. The AEM10941 charges the supercapacitors up to 4.5V and the outputs are enabled down to 3.6V. Let's say you have two 10F supercapacitors and your application draws 80mA from the 3.3V output, then it will run up to: 10F*(4.5V-3.6V)/0.08A= 112.5s
Q&A about supercapacitors
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