Supercaps are a alternative to batteries at least in some cases, but their abilities are very different. I have performed the test as a battery test, making it easy to compare to batteries.
Something to note:
Supercaps has a fairly low voltage rating, for higher voltage they must be used in series and this will require a balancing circuit.
This type of supercap can handle extremely high current both charging and discharging.
The discharge and charge curve is linear and the capacitor can be discharge to zero without damage.
The capacitor has a fairly high self discharge.
This supercap is roughly the size of a D cell, but the capacity and energy contents is much lower (about 1/10 of an AA cell).
Note: I cannot maintain the 20A discharge below 1.4 volt, at 1 volt it is about 15A.
The discharge is very linear and can go all the way to zero volts.
1 watt for about 15 minutes can the capacitor deliver.
First test run discharged the supercap.
I only charge with 1A current, it is possible to charge considerable faster.
Conclusion
Compared to batteries the capacity is very low and cannot really replace a battery. It is more useful for high current pulses or equipment that only needs a low amount of energy and stays on a charger most of the time.
@HKJ: About that kickstarter project using supercaps:
I quite often hear people saying that one day we will have smartphones or electric cars that can be charged in 1-2 minutes.
Although the battery/capacitor technology may become available one day, what people don’t realize is that you would need an AC to DC transformer 10 times bigger than the smartphone or the car to achieve that.
no circuitry at all, just the caps in series, and the battery to recharge them with (though i suspect the car alternator charging the lipo battery won’t work well long term)
The car would charge with 14-14.4V to 6 supercaps in series (i would not use the lipo battery as the guy didn’t in the video i linked)
As I wrote above, over voltage might* damage them, people that are used to working with capacitors always add a balancing circuit to avoid any problems.
*If the voltage is high enough it WILL damage them.
I saw a circuit with a led and a diode in series for each capacitor. It is not the best circuit, but it is simple and will probably work as long as the capacitors has about same value (They change value with age).
But this balancing circuits only discharge overcharged caps and don’t prevent overcharging them or am I wrong.
If somebody would charge a couple of caps with some Amperes the leaking of 30mA seems to be no ideal thing.
Or does short time overcharging don’t harm these caps?
I just followed the link to the battery starter with a lipo attached and I am wondering why not directly use a lipo pack? These are often rated for high currents…?
Maybe I have t understand how the balancing works… I will check it a bit further…
This video shows what I mean very good
So it doesn’t prevent overcharge in all conditions…but it works good enough for being so cheap…