When trying to drive an LED at the output, my output voltage dropped dramatically because I was overloading supplying circuit. It had taken me a while to figure out why my supercapacitor was not charging (or was charging incredibly slowly). Eventually I realized that was happening for the same reason my output was dropping. I didn't have a current limiting resistor for my storage cap, so it was trying to draw a lot of current to charge up very quickly, this itself was overloading the supply.

This isn't too surprising as this type of circuit is not meant to power a lot of stuff directly, but to trickle charge a battery or capacitor.

I need to charge the storage capacitor as quickly as possible, while being realistic about the maximum current draw available to me. My next test was to assume 5mA constant draw without affecting the output voltage (way too optimistic).

Since I want this to charge as fast as possible, I want the lowest resistance value I can get, so I've selected the lowest output voltage available to me.

Since fully charged is about 5 periods of the time constant, this would take over 40 minutes to fully charge. This time gets even worse if my device can't source 5mA without overloading (which is not likely) This isn't ideal for my application as I want to be flashing an LED after several minutes at the very latest.

Because of this long charge time, I won't be using a supercapacitor for the main function of this device. I will consider it for other uses possibly including running the fan, or charging a phone. Once the device is not in use, it still holds a temperature differential for quite a while, meaning there is more energy to be harvested.