Homemade long term electrolytic caps. Finding an electrolyte recipe.

[james_s]

I'd never heard of nickel-iron batteries, sounds interesting. Nickel is expensive stuff though, isn't that the bulk of the cost of NiCd and NiMH batteries?

[CatalinaWOW]

Wait a minute... where did the 100F figure come from ? 

In your original post you state you want to store wind generated electricity.  One of the responses showed that it would take a 100 F capacitor to store enough energy to light a 100 W bulb for 1 hour.

You guys are off by more than an order of magnitude.  A 100F capacitor charged to 120 volts would light a 100 watt light bulb for only two minutes, not an hour.  You need a 3000F capacitor to get an hour.

That is, of course, assuming that your (Batteroo-Brand?) boost converter can slurp all the energy from the capacitor, over an input voltage range of 0 to 120 volts, with 100% efficiency.

A 3000F parallel-plate capacitor with a .001 inch plate spacing, aluminum oxide dielectric (dielectric constant of 8.4) requires about 400 square miles of aluminum foil.  Even once you double the effective surface area by rolling it up to use both sides of the plates (200 square miles) and increase the surface area by roughing the surface, I don't see how this idea is even remotely feasible, no matter how close you might be able to make the plate spacing.

You need electrochemical cells or pumped storage or something to even begin to be in the realm of being possible.  Even thinking about being able to store that amount of energy in an electrostatic field is pure insanity!   

I didn't check the original math or yours, but we agree that lots and lots of Farads are required for meaningful energy storage.  But there are other math errors.  The effective plate separation for an electrolytic capacitor is the oxide thickness, not the separator thickness.  Which for a 500 V capacitor will be on the order of 50 microinches.  So now you are down to 10 square miles, without surface etching.  Which might get close to another order of magnitude.  Still enormous, but maybe doable.

As an older guy capacitors are one of those things that make me leary of the word impossible.  When I started electronics a 50,000 microfarad capacitor was an enormous device, expensive and impractical for most applications.  The largest capacitors used widely were a couple thousand microfarads.  Any engineer on earth would have laughed at you if you discussed making capacitors measured in Farads.  Now you can buy low voltage capacitors in values of 100s of Farads, and they aren't much bigger than those beasts from the start of my electronics career.

Still doesn't make capacitors a good choice for energy storage, except as a stunt with little real use.

[james_s]

Sure but I think it would take an exceptionally dedicated hobbyist to hand build a capacitor equivalent to the average off the shelf electrolytic cap available back then. Something comparable to a 1950s electrolytic capacitor might be feasible. The modern compact high value stuff is the product of billions of dollars of R&D and state of the art factories.

[NMNeil]

Google Robert Murray-Smith, he's working on similar experiments.
Draw your own conclusions on their validity, but his video's are fascinating a lot of people. 

[albert22]

I'll stick with my still-functioning original Wang 2200 system from the 1970s, thanks...   It is made from 7400 series logic, uses 74181 ALUs for the main math functions.  That's plenty big enough for me... 

I really should make some videos of that system sometime. 

I would love to see the wang 2200 videos. I started my career as a technician servicing wang 2200T, VP, MVP and VS. Brings back good memories. I still have manuals and parts from that time.
Best regards

[drussell]

I would love to see the wang 2200 videos. I started my career as a technician servicing wang 2200T, VP, MVP and VS. Brings back good memories. I still have manuals and parts from that time.

Not to hijack the capacitor thread, but I always find it interesting to find another person who "cut their teeth" so to speak on the 2200.  It was certainly the first computer I ever used, before my aunt and uncle got their PET and many years before we got our first home computer (a TI-99/4A.)  My father's business used the 2200 MVP well into the 1990s (we even had the terminal emulator package for a couple of XT-class PCs to use instead of 2236 terminals) and I could have kept it running for much longer but we moved offices and wanted to downsize the physical space requirements away from the Wang equipment and went to PCs with thin coax.  I can't recall if we kept using the band printer for a while at the new office or not...

I have a working 2200 LVP (well, the 8 meg Shugart works, I haven't been able to get the 8" floppy drive to work for many years, need to look into that) and a working 2200 MVP that used to have an 14" 80 meg CDC Phoenix connected to it which I dismantled many years ago for parts (a high school student at the time, my parents said I could only keep it if I dismantled it for parts ) but still have the fixed platters stored in a sealed box and about 6 of the removable disk packs for it, in case I ever find another Phoenix.)  The band printer was also a "keep if you dismantle for parts" deal.  I also have a stalled long-term project on the go for an IDE disk interface card (good ol' parallel IDE, none of this SATA rubbish) for the 2200 series that I would love to find time to finish.

I only have a couple of 2236 terminals left and the foamies in the keyboards are going to need some kind of refurbishment very soon but are otherwise operational.  I also have a working 2235 dot matrix printer and some other miscellaneous pieces for 2200s and some remnants of one of the word processing systems or somesuch that uses the twin coaxial connections.  I never saw that operational, I just grabbed it in a big load of Wang stuff many, many years ago and they're still in the horde.    I have the (5 meg ?) 14" drive for that system but it just throws a fault light and won't even load the heads.  I don't think there was ever an interface for that style drive to the 2200, though, so it is pretty useless to me, I guess.

[LaserSteve]

The actual amount of Ni in a modern Edison cell would be a fraction of what Thomas's technicians would have used.  By the Time the Edison Battery Company started, Thomas had many contract researchers, with a rule about his name going on the patents...

Plate it on a iron substrate or use the course powder or flake only on the electrode surface, job jobbed....

Yes, it would be expensive initially, but no where near what its going to cost to make a high current density connection to  to Al foil, or roll or pack capacitors.
Ni-FE is nearly indestructible if cared for.

Steve
 

[carl_lab]

@Refrigerator
I'm sure you're wasting your time.
You will never reach capacity or lifespan of recently available supercaps, probably not even conventional electrolytic caps.

Supercaps/Ultracaps are used if you need high charging/discharging current in a short time.

https://youtu.be/EoWMF3VkI6U

The benefit of supercaps compared to accumulators is high current ability and very high cycle number (500000) - not high capacity (Wh).

Here is an overview of available maxwell supercaps:
http://www.maxwell.com/images/documents/Product_Comparison_Matrix_3000489_2.pdf

Biggest singe cell of these is 3400F - 2.85V - 3.84Wh, max. current 2000A (!). Dimensions d=60mm , L=138mm
Your 100W bulb can be powered for 3.84Wh/100W=0.0384h=2.3min by one of these 3400F/2.85V supercaps.
If you want to power it for 1h, you need n=60/2,3= 26 of these caps.
I think these are about 45 US$ per piece, so your cap battery is about 26*45US$=1170US$ ... 
You can buy 23 lead-acid car batteries (12V/36Ah/432Wh) for that money!
And the car battery has 4.32x the energy of your maxwell supercap battery.
So supercaps are about 23*4.32=100 times more expensive per Wh.

Some more random web finds:
http://www.altenergymag.com/article/2015/06/ultracapacitor-usage-in-wind-turbine-pitch-control-systems/20392/
https://gigaom.com/2011/07/12/how-ultracapacitors-work-and-why-they-fall-short/
http://www.angliac.com/epcos/literature/EPC690037600.pdf
http://budgetlightforum.com/node/33167

https://youtu.be/8miq6sDy0wA

[TimFox]

Note that the energy stored in a capacitor is (1/2) x (charge) x (voltage), but the energy stored in a battery is (1) x (charge) x (voltage).  As you discharge the battery over its useful range, the voltage does not sag (much), but the voltage across the capacitor sags proportional to the charge removed.
Note that this is true independent of the series resistance in the capacitor circuit.
Therefore, I second the recommendations above to use an appropriate storage battery rather than a capacitor.

[Conrad Hoffman]

Mogami cable company has some fun puzzles. Here's one- http://www.mogami.com/e/puzzle/pzl-03.html

Back up one level on the URL to see the rest.

[carl_lab]

As you discharge the battery over its useful range, the voltage does not sag (much), but the voltage across the capacitor sags proportional to the charge removed.

You're right.
You need a DC-DC converter with wide input voltage range for (halfway) efficient use of the stored charge and for stabilization of output voltage.

Using an accumulator (lead-acid or lithium) is more simple, much cheaper, simply better solution for storing energy of a wind generator.

[JPortici]

Sure but I think it would take an exceptionally dedicated hobbyist to hand build a capacitor equivalent to the average off the shelf electrolytic cap available back then. Something comparable to a 1950s electrolytic capacitor might be feasible. The modern compact high value stuff is the product of billions of dollars of R&D and state of the art factories.

he coulse resell them to audiophools then

There is nothing like the sound of an handmade capacitor. only the best salts for electrolytes, not that goop the commercial units get to use.

"My grandma was from russia, where she used to work in a chemistry lab as a cook. She passed down this recipe she spent a lifetime on perfecting"

Joking aside, i've been followig the topic these days. very cool project

[Refrigerator]

Google Robert Murray-Smith, he's working on similar experiments.
Draw your own conclusions on their validity, but his video's are fascinating a lot of people. 

I've been watching his videos for over a year now. 

[newbrain]

[...]
he coulse resell them to audiophools then

There is nothing like the sound of an handmade capacitor. only the best salts for electrolytes, not that goop the commercial units get to use.

"My grandma was from russia, where she used to work in a chemistry lab as a cook. She passed down this recipe she spent a lifetime on perfecting"

Joking aside, i've been followig the topic these days. very cool project

You might be joking...
But this guy might not...and these definitely are not.

The combination of some morals and the impossibility to keep a straight face is for sure limiting my money making possibilities.

[JPortici]

that doesn't surprise me at all.
i find these people that begs at you to be scammed to be somewhat fascinating.. and i laugh inside when they "find out" they were scammed

[Nerull]

Capacitors are intended for temporarily storing small amounts of energy for rapid use. Why on earth would you want to hook one up to a generator?

A device intended to store large amounts of energy in a relatively small space for use at a later time already exists. It's called a battery.

I used to work for a medical device company which manufactured defibrillators. They used a battery to charge a couple of pretty massive foil caps up to 2000V, then dump this energy into a set of electrodes. A high energy shock is about 300J. A single AA battery stores 40 times more energy and you could fit a whole lot more of them in the same space.

[newbrain]

Last ones on those above link do look a damn nice.

And they'd better do, at >350$ a pop (after discount!) .

Sorry for derailing the thread...but I think the OP got their answer: batteries.