Supercapacitor + Raspberry Pi
I have been interested in supercapacitors for a while. These components are boosted up versions of the humble capacitors found in most electronic products. A capacitor is a component that can store energy, in a similar way to a battery. Normal capacitors – aka caps – only take very small charges (typically measured in Microfarads), and they are often used for cleaning up spikes and noise in power supplies. Supercaps can store much more (measured in Farads), which presently makes them almost suitable as battery replacements.
What’s wrong with using batteries?
– They take a long time, and fairly complex charging circuits, to charge. A super cap can be plugged in a standard power supply with addition of just two components, and charge in minutes.
– They have a limited life span, generally around 1000 charges, after what they have to be recycled, a tricky business. In theory, a well-treated super cap will last almost forever.
I have run a couple of tests with current supercapacitor technology. I found all the info I needed about supercapacitors in this instructable.
One if my experiments was to build an 8.1V, 120 Farad capacitor array, that should be sufficient for powering a small robot or microcontroller. It is made of 6 x 360Farad, 2.7V supercaps. First test: to supply power to a Raspberry Pi. It works fine, but with this configuration (8V 120F converted to 5V) I only get approximately 15 minutes of operation, and that’s without powering a display.
The bright side is the speed of charge, around 3 minutes with my bench power supply (2.5A).
Erm… Not sure what these supercaps will be good for, maybe a secondary power for mobile robot. The fast recharge rate could make it a good combination with a conventional battery to provide continuous operation.