I've started this thread so Supercapacitor discussions can be moved here.
I had a Maxwell 15v 56f supercap in my van a few years back as a replacement for the 12v aux battery, it frightened me to death! I find the thought of a 144V one even less appealing due to the amount of energy they can releasse in a short space of time. A battery at least has the benefit of some internal resistance to limit the current a bit. I think the Maxwell caps could deliver 6000A in a short circuit if I remember correctly.
As battery technology has improved we are now at the point when batteries can directly absorb the regen anyway without an intermediate stage. In fact it would be nice to increase the regen from the stock 50 to 100A.
The discreet parts of the Prius Buck/Boost Converter are quite compact so that it is possible that containment might be found within a capacitor bank enclosure and only the less lethal input/output conductors are exposed.
I think the Maxwell caps could deliver 6000A in a short circuit if I remember correctly.
What to worry? All that battery resistance caues heat and subsequent fires. A super cap, if short circuited will be as close to disintegration as Hollywood can produce on screen. :P
Very very reliable fast acting fuses that can cover any spike amperage placed inside the enclosure before any wiring leads outside would be ideal.
The issue that I see with capacitors, supercap or not is the issue of capacitor aging which would be an issue if you had the capacitors connected to your battery pack(if the caps aren't replacing the battery) as it would drain your battery unless it was disconnected from it. I just tried to find a Youtube video that I just watched a few weeks ago that shows a capacitor system that allows for about 10 seconds of extra acceleration power to allow for cheaper, lighter, more compact, yet less powerful lithium batteries to be used in a vehicle without damaging them when subjected to higher peak loads that have to do with acceleration.
The Honda J-Vx concept car that the Insight was based on was a supercapacitor concept(possibly only on paper, not sure if this was tested). GM did tests with the EV1 using supercapacitors, among other experiments like using a jet engine and rotary engines(in different instances) to try to do what is being done with the Volt now with it's series-hybrid design.
I haven't seen a capacitor system that is cheap enough or small and light enough to make it worth doing. I look to the battery world and see lithium that can discharge at 40C with minimal voltage sag and charge at 5C and with rates like those and their small size, being so light, and getting cheaper by the day, I don't see why I'd want to use capacitors. I see the advantage of a cycle life to where they seem to never wear out, but that's about the only advantage that I think I'd use but I don't think the cost of supercaps makes them work out in the end.
The superior efficiencies and durability of a capacitor system compared to a battery setup for rapid storage of energy and consistent repetitive charge/discharge cycling required of regen/assist, especially in city driving, are well documented. One really big problem appears to be cost and maybe Moore's law will apply with supercaps as well as with lithium ion batteries.
What to worry? All that battery resistance caues heat and subsequent fires. A super cap, if short circuited will be as close to disintegration as Hollywood can produce on screen. :P
Here is what a 250VDC capacitor bank looks like when shorted: Video - Breaking News Videos from CNN.com
this is less than 1 farad, most supercaps are in the thousands of farads.
What to worry? All that battery resistance caues heat and subsequent fires. A super cap, if short circuited will be as close to disintegration as Hollywood can produce on screen. :P
In the late 1800's and early 1900's when gasoline was first used as automobile fuel, serious objections were raised and rightfully so. Gasoline is extremely dangerous stuff but we have learned to live with it to a point where even the most technically challenged are able to refuel safely and we rarely give gassing up a second thought. Hopefully, we can learn to live with supercaps a lot sooner than a hundred years.
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Supercapacitors
