Free Energy | searching for free energy and discussing free energy

New Battery systems => Super capacitors => Topic started by: hartiberlin on November 26, 2009, 05:51:54 AM

Title: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: hartiberlin on November 26, 2009, 05:51:54 AM
Well,
you can build yourself pretty cheaply supercaps yourself.

Just use aluminium foil as one layer and put a little wet only papertowel with saltwater
over it and then use graphite powder on the wet paper towel and then pack as the top layer
a plastic wrap sheet plastic foil (the type from the supermarket).
Then roll these stacked layers up and use a graphite pencil mine from a pencil to make contact to
the graphite powder layer.
The other electrode is the alufoil.

Use a power supply not more than 2.5 Volts to charge up this selfmade supercap.
The graphite pencil electrode is the positive pole
and the alufoil the negative pole.

So you need to hook up the positive output from the power supply to the
graphite electrode and the negative pole from the power supply to the alufoil.

Depending on how large you make the surface area of these sandwiched layers you
will get a few Farads worth of great capacity.

You could also just use only 2 graphite layers, but then the voltage and capacity is lower.

Then don´t charge it up over 2.7  Volts as then electrolysis will happen which will destroy
the alufoil and could produce hydroxy gases.

Then you can measure with a load resistor the capacity of this selfmade supercap
by watching, when it will have discharged to the timeconstant RC voltage level = 0,368 % of the full voltage
tau=RC  => C= tau/R

So for example if you charged up this selfmade supercap to 2.5 Volts and hook
up a 100 Ohm load resistor, watch ( count the seconds) , when the voltage will have decreased to
2.5 Volts *  0,368 = 0.92 Volts and use this time in seconds to calculate the capacity C.

In this example, if the time it took to discharge from 2.5 Volts to 0.92 Volts was 200 seconds,
the  capacity would be:
C= 200 seconds / 100 Ohm= 2 Farad.



Also red and yellow LEDs could be directly powered by such a DIY supercap.

Have fun and post a few pictures of your selfmade supercap.

P.S. Charcoal is not very conductive, but you could also try it with it.
But better use the method posted over here to make your own real
highly conductive graphite powder from a real coal briquet.

See here:
http://www.overunity.com/index.php?topic=790

Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: RAF on November 26, 2009, 07:16:07 AM
Again I’m not sure if this is rude or not,

as I understand, The super caps use activated carbon.
I thought of trying this as well ,,,,, “out side the house”
activated carbon has more surface area than carbon and
can be bought at most hardware stores in the form of
drinking water filters. It will need a good crushing,
maybe some screening to get a consistent grit size.
Oh Ya you can get this at the fish store too.

Just a thought

Al
Title: Shewbread High density Carbon Capacitor
Post by: onthecuttingedge2005 on November 26, 2009, 07:59:02 PM
I am conducting an experiment right now in making high density carbon capacitors using burnt bread, the bread remains porous as it is being toasted into a peace of black carbon with ultra high surface area.

I will test the conductivity first, if it pans out I will see about fixing some aluminum foil contacts for terminals.

if the experiment is successful then I will proceed to assemble a Shewbread capacitor pile and test capacitance.

Jerry 8)
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: onthecuttingedge2005 on November 26, 2009, 08:21:36 PM
after a kitchen full of smoke from toasting the shewbread to a pitch black peace of carbon the conductivity test is successful.

the peace of burnt toast measures 1/4 inch in thickness and measures 23M ohms in resistance from backside to front side. this is a good sign.

it will help if a flat weight is placed on the shewbread while toasting to prevent deformity of the bread so that the bread remains flat.

after the thanksgiving festival I will assemble the Ultra cap pile to test for capacitance.

happy thanksgiving to all.
Jerry ;)
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: onthecuttingedge2005 on November 27, 2009, 01:36:52 AM
the plan
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: onthecuttingedge2005 on November 27, 2009, 04:32:51 AM
here is what I am settling on for the first prototype of the Shewbread Capacitor.

any idea's to add?
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: onthecuttingedge2005 on November 27, 2009, 05:42:31 AM
just a reminder.

for the shewbread capacitor.

1. remove the bread crust off of the bread with a razor blade.

2. use a mold or a flat plate(not to heavy) and place it on top of the bread to keep the shrinking of the bread from deforming the bread while it is being converted to carbon. if the plate is to heavy you might lose some of your porousness in the carbon once toasted to a charcoal consistency.

3. use proper ventilation when over toasting your bread. lots of smoke!

4. when selecting your bread of choice, look for the amount of pores per square centimeter, the greater the pores the better the surface area.

5. ask yourself, why did he call it a shewbread capacitor? look up shewbread on wiki and you'll find out why I called it a shewbread capacitor.

6. try to get the burnt toast as close to 99% converted to porous carbon and to make an analogy of this, it is a burnt offering before the Lord. lol

7. just to make this more weird, I am a son of David and a Carpenter. for those are names not professions. I have been drinking a little but I have not told any untruth.

I always get spiritual when I am drinking, I guess it is the spirits in the drink! I do apologize for all those atheists. I do try to keep this on a professional level when I am sober though. but hey. it is Thanks Giving and so. I am giving.

8. remember, if you become rich off of my idealism then please contribute to my spaceship, I would greatly appreciate it. I have a spaceship to build.

Jerry 8)
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: hartiberlin on November 27, 2009, 01:42:32 PM
after a kitchen full of smoke from toasting the shewbread to a pitch black peace of carbon the conductivity test is successful.

the peace of burnt toast measures 1/4 inch in thickness and measures 23M ohms in resistance from backside to front side. this is a good sign.

it will help if a flat weight is placed on the shewbread while toasting to prevent deformity of the bread so that the bread remains flat.

after the thanksgiving festival I will assemble the Ultra cap pile to test for capacitance.

happy thanksgiving to all.
Jerry ;)

Hi Jerry,
interesting idea with the burnt toast, but:
1. You should definately do that outside as inhaling the smoke is dangerous
2. 23 MOhms is much too unconductive !

Just use the method to fire up a few coal briquets and let them
glow hot red for a while and when they have a white ash surface
and will still glow inside, then the carbon from the coal has transformed
to a very good conductive graphite...

They then look as if they have almost completely burnt up,
but when you put them into a metal box, so it kills the oxygen air supply,
the burning will stop and inside the white ash they will still
have black powder, which is the graphite.

( Be careful, the metal box will get very hot
as they have stored a lot of heat energy, when they
still glow read hot !)

This graphite then will have about 10 to 100 ohms per cm distance,
which is very nicely conductive.
This good conductivity is needed for a good supercap.

Regards, Stefan.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: teslaalset on November 27, 2009, 02:05:03 PM
Graphite powder can be easily bought online. It's about 10 euro/kg, e.g:
http://www.kremer-pigmente.de/shopint/index.php?cat=0102&lang=ENG&product=47710 (http://www.kremer-pigmente.de/shopint/index.php?cat=0102&lang=ENG&product=47710)
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: PaulLowrance on November 27, 2009, 03:35:05 PM
What a great thread! Here's a good forum on ultracaps that includes numerous threads on how to make homemade ultracaps,

http://www.ultracapacitors.org/

Here's one thread, titled, "Home made supercaps"
http://www.ultracapacitors.org/index.php?option=com_fireboard&Itemid=99&catid=8&func=view&id=339

If someone has a program to backup this thread, then that would be great in case something happens to it. This guy go into detail how to make a DIY supercap. Some of these DIY supercaps are at least 150F.

Regards,
Paul
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Paul-R on November 27, 2009, 06:24:36 PM
What capacity and voltage rating are you guys expecting?
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: MileHigh on November 28, 2009, 12:28:13 AM
Quote
What capacity and voltage rating are you guys expecting?

Great question!  I have a feeling it is going to be in microfarad territory, not supercap territory.

Experiment and learn as they say.  You will probably need scopes to measure your capacitance's.

MH
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: hartiberlin on November 28, 2009, 03:45:14 AM
It depends only on the surface contact area between the alufoil and graphite.

If you are using 1 x 1 meter of alufoil and 1 x 1 meter of graphite paper,
you should expect a capacity in the range of 100 Farad or more.

Have a look at this good PDF file:

http://www.ansoft.com/firstpass/pdf/CarbonCarbon_Ultracapacitor_Equivalent_Circuit_Model.pdf


Regards, Stefan.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Robert on April 06, 2012, 05:41:37 PM
AA batteries have carbon cores that can be reused....

Old batteries is an endless supply of carbon powder.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: V_Schaub on March 20, 2013, 04:09:24 PM
Hi.
I have few questions regarding the main design in this topic.
In my test project i want to create 400V capacitor bank to charge one 2kw device for one hour.

1.) How much supercapacitors should I build to make this work and how much Farrads should one SC need to have ?

2.) If i use aluminum/salt/graphite (active carbon or maybe graphene ) design, would it be possible to create 400V / 200F capacitor ? The size does not matter, it can be big cca 1 meter and over 50cm thick

3.) When you put saltwater between graphite and aluminum you have created battery. My question would be:
What will happend when aluminum will be coated with aluminum oxide. Basically when aluminum starts to oxidize ? Will the supercapacitor still work / will it loose its capacity or something else ?

4.) What would happend if i would use carbon or graphite as second plate ( instead of aluminum ) ?

Thank you in advance for your ideas/comments !

 
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: triffid on June 19, 2014, 10:57:32 PM
test,wanted to have a link back to this thread.I want to make supercapacitors now.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Brian516 on January 20, 2015, 11:44:01 PM
Question:   

Are you doing this with Charcoal Briquettes or actual Coal???
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Paul-R on March 24, 2015, 06:35:32 PM
Having built the capacitor, when using it as a replacement battery,  how do we regulate the output voltage to give a fairly constant voltage as the cap discharges?

(Obviously, a voltage regulator would do this but will waste most of the power).
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: MarkE on March 24, 2015, 07:18:37 PM
Having built the capacitor, when using it as a replacement battery,  how do we regulate the output voltage to give a fairly constant voltage as the cap discharges?

(Obviously, a voltage regulator would do this but will waste most of the power).
Votlage regulators don't all waste most of the source power.  Many switching supplies are well above 90% efficient, and some specialty designs are over 99% efficient.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Spilled Fluids on May 17, 2015, 05:52:01 AM
Votlage regulators don't all waste most of the source power.  Many switching supplies are well above 90% efficient, and some specialty designs are over 99% efficient.

Mark,
What about the Robert Murray Smith self charging graphene super cap. If it truly recharges itself then it has to be at a minimum 100% efficient...no?
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Red_Sunset on May 17, 2015, 08:12:56 AM
Having built the capacitor, when using it as a replacement battery,  how do we regulate the output voltage to give a fairly constant voltage as the cap discharges?

(Obviously, a voltage regulator would do this but will waste most of the power).

Paul,
By definition a "voltage regulator" in the old school understanding did waste a lot of power, they were also caller "series regulators" because the regulation was done in a semi analog fashion by venting excess power into a transistor regulator as heat. They were heavy due to the transform iron block inside and not efficient at all due to the analog power venting.

The integrated circuit age provided much more efficient regulation using switching regulators using the "buck/boost" principle,  now commonly used in all electronic appliances, one common one you handle every day is your mobile charger. 
No big iron block transformer, so very lite an efficient due to the digital power switching duty cycle which regulates according to need. Power regulation is done from DC to DC (AC is rectified first).  Voltage regulation can be done in both direction, the output voltage can be smaller or greater than the input (Buck/boost) and is very efficient due to the low power loss switching (the reason for using power FET's).
Some Gooling will find you all you need

Red_Sunset
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Pirate88179 on May 17, 2015, 08:25:31 AM
Paul,
By definition a "voltage regulator" in the old school understanding did waste a lot of power, they were also caller "series regulators" because the regulation was done in a semi analog fashion by venting excess power into a transistor regulator as heat. They were heavy due to the transform iron block inside and not efficient at all due to the analog power venting.

The integrated circuit age provided much more efficient regulation using switching regulators using the "buck/boost" principle,  now commonly used in all electronic appliances, one common one you handle every day is your mobile charger. 
No big iron block transformer, so very lite an efficient due to the digital power switching duty cycle which regulates according to need. Power regulation is done from DC to DC (AC is rectified first).  Voltage regulation can be done in both direction, the output voltage can be smaller or greater than the input (Buck/boost) and is very efficient due to the low power loss switching (the reason for using power FET's).
Some Gooling will find you all you need

Red_Sunset

Or, could you not just use the proper supercap for the application?  In other words, I use a 2.7 volt supercap (650 F) to light an led.  The voltage is fine as it is and the led only draws what it needs and it will run for a very long time.  No other components required that would waste energy.

Or, am I missing something?

Bill
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Red_Sunset on May 17, 2015, 01:05:26 PM
Or, could you not just use the proper supercap for the application?  In other words, I use a 2.7 volt supercap (650 F) to light an led.  The voltage is fine as it is and the led only draws what it needs and it will run for a very long time.  No other components required that would waste energy.

Or, am I missing something?

Bill

Bill,
I am not sure if I understand correctly the question or issue at hand. So I might also be missing something.
Voltage or current regulation is required to keep one or the other at a specific value. 

To charge a cap to max. 2.7 v,   a regulator would limit the voltage

To drive a LED, you need to control the current, depending on LED type,  20-30ma for a common variety bright LED.  The LED junction voltage is determined by the LED type and color.  This LED power control is usually done by a series resistor which limits the current and picks up the excess voltage.
A current regulator could be used to do the same thing and save on the wasted energy by the resistor. In addition it can compensate for a discharge descending voltage.  Because if the CAP voltage drops below the LED junction voltage, the LED will switch off. The regulator could compensate for this simular to a MPPT charger/regulator used with solar panels (Maximum power point tracking (MPPT)   It is a technique that solar battery chargers and similar devices use to get the maximum possible power from one or more photovoltaic modules. 
MPPT is a type of intelligent buck/boost according to need to extract most power at any time and extend the usable charge time.

Red_Sunset
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Doug1 on May 17, 2015, 02:36:10 PM
I know what your saying Bill. it's just a communication difference. Bill is using the cap as a battery with a near matching voltage to the load in which case no regulation would be required. On the charging side there is need for regulation if the supply is ac and or over/under the target voltage to be put into the cap. I think Bill would first look for a source that is matched  to the target voltage then move on to other sources requiring more exotic components to regulate and step up or down as needed. The cap will deplete over time but not above the voltage it was supplied with. The load usually has a window or spread that it will function with in, example led working at full bright at 3v down to 2v but with lower brightness as voltage decreases down to the point it will not light any more.
  Just like the cap battery replacement on his car. The caps will still start the car even with less then optimal voltage.
  Bill have you looked at the self charging cap idea yet? I found the pdf link without paying for the abstract lol .
http://www.nanoscience.gatech.edu/paper/2013/13_AEM_01.pdf . I think the pizo thing was considered back in the days of the CC forum.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Pirate88179 on May 17, 2015, 06:31:32 PM
Bill,
I am not sure if I understand correctly the question or issue at hand. So I might also be missing something.
Voltage or current regulation is required to keep one or the other at a specific value. 

To charge a cap to max. 2.7 v,   a regulator would limit the voltage

To drive a LED, you need to control the current, depending on LED type,  20-30ma for a common variety bright LED.  The LED junction voltage is determined by the LED type and color.  This LED power control is usually done by a series resistor which limits the current and picks up the excess voltage.
A current regulator could be used to do the same thing and save on the wasted energy by the resistor. In addition it can compensate for a discharge descending voltage.  Because if the CAP voltage drops below the LED junction voltage, the LED will switch off. The regulator could compensate for this simular to a MPPT charger/regulator used with solar panels (Maximum power point tracking (MPPT)   It is a technique that solar battery chargers and similar devices use to get the maximum possible power from one or more photovoltaic modules. 
MPPT is a type of intelligent buck/boost according to need to extract most power at any time and extend the usable charge time.

Red_Sunset

Red:

I may be missing something here also, and I know that you know your stuff but I never use a current limiting resistor when using supercaps.  My 650 F cap has enough current available that it will melt the wires I use if shorted. (ask me how I found this out, ha ha)  But, I can light a single led from it that only needs 20 mA  (Like you said) and it will only draw that 20 mA's.  I have found that as long as the voltage is correct for the given led, then they only draw the current they need and do not fry.  As Doug said, I am using supercaps like I would a battery, and have been doing so for many years now.  Now, if I had a 12 volt supercap and only wanted to run my 3 volt led from it, of course I would need to use the right resistor in that circuit, or that led will fry in less than a second.  (ask me how I know this too, ha ha)  Doug is also correct in that as the voltage drops in the cap, the led will dim over time and finally go out when the cap voltage is below the led's minimum voltage requirement but, with so large a cap, that can take a really long time to happen.  I like using them as they charge up very fast.

Doug:

I will look at that pdf.  Nice job on getting it for free, ha ha.  I had never heard of anything like this.

I have been following Lasersaber's work on replacing his car battery with the cap banks and, the latest version uses some pretty small caps
compared to what he started out with yet, it starts and runs his truck just fine...so far anyway.  They appear to recover from the starting draw very fast as well.  His meter on his last video (I think it was the latest one, maybe the one prior) showed they charged back up in a matter of seconds after his truck started.  He does some interesting work.

Thanks,

Bill
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Doug1 on May 18, 2015, 01:25:48 PM
Bill
   I was wondering the net trying to remember the title of a vid that showed a person burning a pile of powedered Tiso2 under a plate of glass to produce a conductive layer that was transparent. Along the way I ran into an add for liquid glass and followed the bread crumbs. It can be made from diatom powder. In the short form the single cell critters cell walls are made of Tiso2. This is a cheap product used for a filtration medium for swimming pools and aquariums that will filter down to a micron or two size contaminants from water. When it is not burnt into a gas I think has insulating properties that may be viable applied to one of the electrodes of a making up a cap. Being it is a hollow structure with two valves one of which is naturally larger then the other for it to feed and expel waste through it should be able to retain a liquid conductor. Acids may not be suitable without damage to the cell structures but iodine diluted in distilled water should work just fine to produce a really thin insulator and a electrolyte  that easy to apply and easy to get. For the purpose of making lower voltage caps. The wider the gap the less effective for lower voltages ect...
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Paul-R on May 18, 2015, 04:15:11 PM
Or, could you not just use the proper supercap for the application?  In other words, I use a 2.7 volt supercap (650 F) to light an led.  The voltage is fine as it is and the led only draws what it needs and it will run for a very long time.  No other components required that would waste energy.

Or, am I missing something?

Bill
I fear, alas,  Bill, that you may be.

An LED takes a current of  approximately nil amp. A potato battery would do  it.

If you are running a 6v motor connected to  a water pump off two of your capacitors,  the voltage would drop from 5.4v to,  say, 4v,  very quickly. It would stop working with about 75% of the energy still  in the caps.

How could we get round this and get almost all the power out of the caps?
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Red_Sunset on May 18, 2015, 06:43:27 PM
....................................................
How could we get round this and get almost all the power out of the caps?

See Reply #22 on: May 17, 2015, 01:05:26 PM
Buck-Boost/Inverter/converter/MPPT
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Paul-R on May 19, 2015, 04:26:54 PM
See Reply #22 on: May 17, 2015, 01:05:26 PM
Buck-Boost/Inverter/converter/MPPT
This is very interesting. not come  across current regulators. But i still  don't understand. Does the device increase the voltage as the cap voltage drops in order to maintain the design voltage, say 6v ? Do you have any part numbers?

The other thing that you may be able to help over is the equation for the equivalence of capacitors and batteries I am getting ridiculous results.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Red_Sunset on May 20, 2015, 07:38:22 PM
This is very interesting. not come  across current regulators. But i still  don't understand. Does the device increase the voltage as the cap voltage drops in order to maintain the design voltage, say 6v ? Do you have any part numbers?

The other thing that you may be able to help over is the equation for the equivalence of capacitors and batteries I am getting ridiculous results.

Paul,
In the DC-DC converter area, there are several simple switching regulators, example MC34063 - DC-DC converter control circuit,  it is just one of the many to be found, you find then also often used in a mobile car charger.  The reason they are inexpensive.
At the rear of the datasheet you will find sample application circuits for up & down converter. They have the ability to convert voltage upwards or downward, ( buck or boost)  Some sensing would be required to implement this seamlessly. Very low pwr usage, 2.5ma.
On the next level up, MPPT IC's are available that have intelligence for tracking capability by incorporating something like a PIC to effect continuous adjustments based on set parameters,  an internet search will provide you a wealth of information.
Sorry I have no direct idea about equivalence of capacitors vs batteries, need to look this up.

Red_Sunset
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Spilled Fluids on May 20, 2015, 08:21:01 PM

....
Sorry I have no direct idea about equivalence of capacitors vs batteries, need to look this up.

Red_Sunset

Check out Batteryuniversity.com ; you will find all the info you want about batteries, capacitors and super caps as well as how they differ in function and construction  8)
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Red_Sunset on May 20, 2015, 09:13:30 PM
Paul, Spilled Fluids,

Thanks for your battery reference site. I couldn't find there immediately what I wanted,
Check out this site:  http://bymark1.hubpages.com/hub/Ultracapacitors-as-batteries

Ultracapacitors as batteries  some details copied and shown below.

We can use the following formula to convert Farads to Amp hours
(Vmin + Vmax)/2 * F / 3600 = Ah
Vmin & Vmax is the upper and lower voltage. This is the voltage range that your device has to work in. As capacitors "run down" and need charging, their voltage drops, so we have to allow for that. If we assume that we want to power a 3 volt radio, we can guess that it should work happily between 3.5 volts and 2.5 volts. That's what the first part of the calculation allows for;
In our example, (Vmin + Vmax)/2 would be (3.5v + 2.5v) / 2 equals 3 volts.

In the rest of the calculation, F - Farads and
3600 - coulomb, a unit of electrical measure. One amp hour = 3,600 C
Ah - Amp hours ( 1000 mAh = 1Ah)
So we now have 3 * F / 3600 = Ah
Let's say we can get hold of a 3.5 volt 100 F super-capacitor. Using 3 * 100 / 3600 = Ah,
we could expect it to power a device drawing 0.083 amps, or 83 milliamps, for one hour.
What if this wasn't enough? What if we wanted a 3 volt capacitor to power a 3 volt device which drew 250mA for one hour?
We can use the formula "current in amps * 3600 / voltage = capacitance needed in Farads" to find out how big the capacitor needs to be. In this example
0.25 * 3600 / 3 = 300 F
The capacitor would need to be 3v 300F to power a 3 volt device drawing 250mA for 1 hour. Ideally, you should have a capacitor of slightly more than 3 volts to allow for the voltage drop mentioned above.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Paul-R on May 24, 2015, 03:12:04 PM
Thanks for all that useful stuff, Red.

But when you say (Vmax + Vmin), you must mean minus not plus. Vmin will be a parameter which reduces the useful overall power capacity of the cap.
Title: Re: selfmade homemade DIY supercap ultracap bcap boostcap
Post by: Red_Sunset on May 24, 2015, 05:07:01 PM
Thanks for all that useful stuff, Red.

But when you say (Vmax + Vmin), you must mean minus not plus. Vmin will be a parameter which reduces the useful overall power capacity of the cap.

Paul,

All what the you are trying to do here is find the mid-range or average working voltage.  Remember it is a value you choose based on what you need as the min voltage for the equipment you are going to connect to the Cap.
To can also find the same average by,  do a minus, then divide by 2 then add to Vmin.
Sure the higher Vmin is, the smaller your working range becomes.  The same as with a battery.  Although with a battery, this value is usually set by the battery type,  the lowest discharge voltage before the battery becomes irrecoverable damaged.

Red_Sunset