Recharge for the Shorter Haul

Thanks for the informative and extensive article.

Looking forward to further and fast, safe, renewable, and cheap, energy dense, portable energy sources for vehicles....

What about ultracapacitors?

Hello tfcheek,

Ultracapacitors can store energy, sure, and quite a bit of it.

The present problem is, that electrochemical methods are more safe and efficient, because the storage is chemical, not electric.

The advantage of chemical storage is there is an extra layer of control, during the release of the energy.

There is a lot of work still to be done on the design and manufacture of Ultracapacitors.

The basic problem with an Ultracapacitor, is that if an internal fault develops, all the stored charge is released internally within much less than a second, acting like a large explosive package, and damages resulting from that.

So...the energy requirement for moving an object (Car) whether by electric motor, diesel power, petrol or Solar is exactly the same, after conversion efficiencies are taken into account.

Because it is not easy to fully vaporise 10 gallons of petrol in air, and ignite it to release the stored energy, petrol is presently safer than an Ultracapacitor which stores the same amount of energy, but could release it all in ¹/₁₀ second or less.

The sudden release of uncontrolled energy from an internal "punchthrough" or "short circuit" of Ultracapacitor dielectric would create a huge fireball, which nothing within several metres could survive.

In old radios, vintage 1950's and earlier, I have seen the damage done by an electrolytic capacitor of some 300VDC and 10µF (microfarad) which developed internal short circuit via "dielectric punchthrough" and exploded the hermetically sealed can, wrecking the radio beyond repair.

Sometimes when these sorts of things happened, the blast from a cylindrical can 3 inches long x 1 inch diameter could be heard over 100 yards away, outside the house, often shattering windows etc in the room the radio was in.

The stored electric energy in that cannister,would not have driven a car even 0.001mm (millimetre).

There were designs some 30 years ago, of using superflywheels under buses, trucks etc, and several test vehicles were tried.

After calculations were done, and it was realised exactly how much kinetic energy could be stored in a large spinning disk, then if there was an accident, or problem with the disk bursting at full rotational speeds, the further development was quietly dropped.

At the time I did some rough calculations,and estimated that a superflywheel spinning at top speed, and becoming free of the retaining bearings and enclorure, would travel several miles, destroying everything in its path, before disintegrating or coming to rest.

"In the mid-90s, Rosen Motors (a technology startup) proposed using a superflywheel in a revolutionary series hybrid car whose prime mover was to be a single-stage microturbine. The flywheel was gimball-mounted and connected to the chassis using Kevlar straps. Investors got cold feet when they figured out that when fully charged, the energy stored in the flywheel was equivalent to that need to lift the vehicle about 20 floors straight up. That would not happen in a crash, it merely illustrates the need for containment" - Refer:

http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=40A5048D-1AE0-4AED-B8B7-1472C964FBE

Kind Regards.....

AC capacitors for home units are sometimes 370volts at 35 uF but I've never heard of any of them exploding? ( we believe you but) Wondering if the modern ones are that much better built or have some internal safety method?

Also same reasoning for H cars using stored H in liquid or even gaseos form. The destructive power is released in perhaps just a few seconds creating a big fireball that few would survive. This illustrates the fallacy of detroits highly touted (blessed buy bush) H car which by the way only goes 50 miles between expensive $ refills. The Electrics conversely are much more safe and much cheaper to operate costing only 1 cent per mile (using Ni-Mh batteries which are very hard to break electrically and backed up by our own experiments on small versions).

yes the 340 v ac capacitors only charge up as dc but accept ac as an input to give a dc starting kick to the compressor motor.

Hello TRIPLEBATTERYLIFE,

If you mean a capacitor used in a squirrel cage single phase as a starting capacitor, it charges up with opposite DC polarity each time the AC mains power reverses polarity - UK electric system = 50 times per second, US electric system = 60 times per second.

The Starting Capacitor in an AC circuit must be rated for AC duty, if a capacitor designed solely for DC duty is used, you generally have an explosion.

The starting capacitor is there only to give increased phase displacement in the start winding of the capacitor start motor.

I does this because the start winding of a single phase squirrel cage motor is thinner wire and more turns of that wire, thus of greater initial inductance than the much shorter run winding at the instant of power being applied.

This increased inductance opposes change, due to the magnetic circuit properties, as shown by the symmetrically opposite curves of inductance and capacitance - they are for units the same: 1 Henry versus 1 Farad actually have mirror image charging curves.

At the instant of power applied, the current into a capacitor may be infinite, reducing as the capacitor charges up, and the capacitor can never be fully charged, because as it approaches the supply voltage, the current diminishes exponentially.

Likewise, At the instant of power applied, but oppositely, the current into an inductor may be very small, because the developing magnetic field opposes any change, decreasing as the magnetic field builds up, and the inductor can accept more current, the magnetic field strength never actually reaches maximum, because of the exponentially decreasing decrease in the electric current.

The two opposing Properties and charging curves are used in timing circuits, tuning circuits in Analogue Radio, Analogue TV, Radar etc.

Further info please refer here:

http://www.cybered.net/commerce.asp?CatId=309&ProdId=X5007122

A useful Software program for electrical/electronic calculations may be found here:

http://www.miscel.dk/MiscEl/miscel.html

Re the above program note:

"The program contains a lot of pages with different electronic calculations. Each page contain one or more different calculations.
The program is free to download and use, but the program is timelocked. A new version will have to be downloaded after about 1/2 year"

So by using a "Starting Capacitor", the increased inductance is counteracted by the capacitance of the Starting Capacitor.

It is the increased phase displacement, and increased momentary current in the start winding, which gives increased starting torque.

If you were referring to a different usage for capacitor, ("starting kick to the compressor motor") please advise....

Our understanding of capacitors in general is that if they are in an ac circuit they still charge up only as dc and therefore can be used to provide not only a surge of power to start a motor but also provide the starting direction of rotation. All the theories support this basic concept . A larger capacitor many times will say some volts ac but that is to provide a limit to what it can safely handle as an input. (don't put 1OkV on it for example). It still only puts out dc as an output. Hope this helps.

Also I have never heard of capacitors of the 30uf @ 300 volt ratings ever exploding so presuming that the manufacturing is better. Weren't old capacitors composed of actually paper inside ? That could deteriorate for sure.

Hello TRIPLEBATTERYLIFE,

I trust you will not be offended by my response to your Post, because I do believe we are both seekers after truth.

You state: "Hope this helps."

But you have clouded the issue, by introducing part facts and also speculation.

"Our understanding of capacitors in general is that if they are in an ac circuit they still charge up only as dc and therefore can be used to provide not only a surge of power to start a motor but also provide the starting direction of rotation."

The starting capacitor for a squirrel-cage single phase motor, is NOT there to "...give a surge of power...", but to advance the otherwise retarded phase shift caused by the inductive reactance of the start winding, at the instant of start up.

That is basic AC Theory.

"All the theories support this basic concept" - Untrue in part, or speculation, because you have generalised, and in this matter it is not possible to generalise the way you have done, and also be entirely correct.

It appears you misunderstand the usage of a capacitor in a motor-starting situation.

"Also I have never heard of so presuming that the manufacturing is better. Weren't old capacitors composed of actually paper inside ? That could deteriorate for sure."

You say you have never heard of "capacitors of the 30uf @ 300 volt ratings ever exploding", yet I have previously stated that many capacitors may and often do explode, if their ratings are exceeded.

Sometimes capacitors explode even if carefully operated within their design ratings.

Experience is the best teacher, so I was often told, and that decided me, very early in life, to obtain wide experience about much, greater experience in certain areas, and when I was not certain, and needed to know the facts, to carefully research the subject.

I did not need to research this particular subject, having seeing my first capacitor explosion at Technical College, back in early 1959, and many hundreds of further exploded capacitors since that time.

This early demonstration was done by the Technical teacher, to vividly explain to the class, the ever-present dangers of both electrical stored energy, and how easily a capacitor operated outside its ratings could explode.

Motor Starting and other capacitors are still being made with paper dielectric - that manufacturing process shows little change for the last 70+ years.

It does not matter whether the capacitors are old or new - they may still explode if operated outside their ratings, and sometimes even if operated within those ratings.

So, whether you have heard...or not...does not alter the facts.

Sincerity of belief is never a substitute for truth.

Try Mr. Google's excellent Search Engine - Search Terms capacitor exploding, (not bold type, of course)

Hope this helps.....It may clarify things for you

Kind Regards.....