I have been bugged all Labor Day weekend about super capacitors. Having used standard capacitors in most of the equipment around here and learned to diagnosis them in single-phase motors for starting and running I have a hardened sense of their value.

Yesterday I posted a bit about them to distinguish them from your everyday capacitor.  So today I’m going to list the links that have in this case, bothered me for a month and another that I saw this weekend.

First up is the report on a press release from the American Physical Society back on July 4th 2007.  The original is nowhere to be found and I have already emailed Dr. Ranjan in hopes of seeing more data.  The release discusses the two polymers that Dr. Ranjan and his team are looking into.  Having mixed up the two polymers, PVDF and CTFE, yields a material whose regions can change structure.  This is thought to greatly increase the stored energy in a capacitor.  See:


This is why it’s so important.  The current state of hybrid autos is engineered so that the gasoline power plant takes over for the electric motor under certain conditions.  Which means the car has a complete drive train for the gasoline drive and an ancillary drive for the electric side.  A super capacitor offers the designer the choice to eliminate the gasoline drive train and simply directly charge the super capacitor and the battery.  That would leave the car with only an electric drive drain.  Saves a lot of weight and simplifies things enormously.  Having adequate capacitor electron inventory allows the driver to have the kind of energy release needed for sudden acceleration.  The gasoline engine would only run to charge the capacitor and battery, thus could be engineered for optimum efficiency.  A car with large enough motors and capacitors would need a rather small charging engine and still be a rip roaring tire smoking machine.  The capacitor needs to be pretty “super” and the battery set could be much smaller and lighter.

With so much focus on “replacing” the battery a huge efficiency gain and cost of entry for consumers to this level of efficiency is being overlooked.

That brings me to the Associated Press story that looks most complete at:


This “story” starts reading, well, like a story with a little hype put in.  It kicks off with the promise, quote “meaning a motorist could plug in a car for five minutes and drive 500 miles roundtrip between Dallas and Houston without gasoline.”  The skeptics get their say starting in paragraph seven.  Count me in for now.  But a little further along the material between the “thousands of wafer thin metal sheets” comes up.  Ah.  See the leading paragraphs of this post.

On the other hand some pretty smart people who aren’t known for throwing money away back EEStor, rather they have pretty good records.  They’ve got their money on some rather good people for research.  The direction they’re going looks promising.  But a 400-fold increase in one step?

The nay-sayers get their points in at the end.  They are all valid points but most are engineering issues other than the 400-fold increase in capacity.

The story doesn’t get very far with the major issues.  Length of time a charge holds, density by weight, linear discharge, although the voltage issue may be switched to a charging issue that could be solved with a transformer.

I’m intensely interested.  Even if the gain is a small portion of the claim in the story this might be enough for auto manufacturers to offer the kind of hybrid I’d like to buy.  I’d like a high efficiency diesel directly coupled to a generator keeping a super capacitor and battery charged to the power the vehicle with enough zoom to get out of the way, run 15 over the limit anywhere in the US for 500 miles and fill up in 10 minutes or so.  I might be willing to spend quite a sum to get that.  I could have a good sized car and get good mileage, too.


2 Comments so far

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