Let's learn about Super Capacitors! (A Practical Guide To Super Capacitors)

Picture of Let's learn about Super Capacitors! (A Practical Guide To Super Capacitors)
Hi Instructables Community!  


                                                    LET'S TALK ABOUT SUPER CAPACITORS!
Thanks for looking at my instructable!  This instructable will be a little bit shorter than some of my others, and it will be written from the perspective of a technician, not an engineer.  This instructable will be followed with similar super capacitor related instructables.  I'm not going to blast super capacitor noobies with a ton of flashy math.  However, I will be providing links to sites where math can be found for those of you who are interested.  I want to keep this document as practical as possible. There are some fun videos in STEP#8 and some links to my hobby electronics stores in STEP#9.  For those of you who don't know much about super capacitors, here is a little bit of fun theory:

Super capacitors act like any other kind of capacitor, only they can store tremendous amounts of energy.  Many capacitors that you'd have seen in audio circuits have capacitances such as 470uf or 680uf (micro farads).  Capacitors used in high frequency RF applications can be as small as 1pf (pico farad).  The farad is a measure of capacitance (or storage capacity).  They are often used in filtering applications, coupling or decoupling applications, or AC-DC smooting applications (there are some large caps in your standard AC-DC power supply that acts to smooth out the ripple on the line). 

Super capacitors can be used in solar power applications, battery back-up applications, battery applications, flash-light applications, etc.  Aside from the fact that the super capacitor can be charged very quickly due to their low internal resistance, which is known as ESR, but they can just as quickly be discharged.  Batteries contain harmful chemicals, and die over time.  If you handle your super capacitors carefully, you will die before they do...Seriously!  Howver, there are rules...

Super capacitors do not give off gas like lead acid batteries, but they cannot store as much power either.  You can place capacitors in series or in parallel to either up the maximum charge voltage, or total capacitorance.  We will talk about this later. 

Really, there is a lot to be said about capacitors, and you're not going to want to spend your entire day listing to me, so let's get down to the basics.  You can go fourth and choose which tabs you;re interested in.   Here is a video just for fun of me starting my car with super capacitors!

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Errol19511 month ago

can I use a 400V capacitor in a 5volt circuit using a 5 volt zener to limit to voltage going into the capacitor if i can how will it effect the cap thanks

Conductor will go red??? Then discharging takes how much time??? And isn't it supposed to make a BIG spark, I do this with my 450v 220uF cap..
I salvage components from my retired electronic devices. How can I identify any of the capacitors are "super capacitors"?

Very high farads in a (relatively) small package. you probably wont find them. The big ones are mostly used as regenerative breaking buffers in large vehicles, sometimes the little ones are used as backup power sources for small ICs (they keep the clock from resetting if the device looses power)

freezier5 months ago

Update: there is now a mosfet that has been engineered just to balance Super Capacitors. They are made by Advanced Linear Devices... google SAB mosfet to learn more. I just ordered a couple from digikey to try out on my bank...

bent16151 year ago
This message is for Rahul Nema. I am trying to do something similar but Engineering guy said it is was not going to be easy and very costly. His advice was to buy batteries. NOW with the advent to the super capacitor out for some time, please let me know what you came up with .. if you did. In my case I have only 1.4kw solar and I dont want lead batteries to gas up the area. You can contact me at my mail at bent1615 at gmail if you like. hope to hear from you. TIA
wobbler bent161512 months ago
For the queries about using supercaps as replacements for batteries, the maths for capacitors to current is pretty simple. You only need two formulae:
(1) CV=Q where C=capacity in farads, V = voltage, Q= charge on capacitor in Coulombs.

(2) Q=It where I=current in Amps, t= time in seconds.

(3) From (1) and (2) we get CV=It

So, if you have a 1F supercap charged to 5v and take 1amp from it, it will last for 5 seconds.

A 100F supercap at 10v will supply 5A for 100x10/5 secs= 200 seconds or 3 mins roughly.

Compare this to a AA 1.25v 2Ah rechargeable. By multiplying the voltage by the current by the time in seconds we can find out how many Coulombs this is equivalent to. This will provide a total of 1.25x2x3600 Coulombs of charge = 9000 Coulombs.

Using equation (1) (C=Q/V) we can see that this is equivalent to a 9000/1.25=7200F supercap. In fact, because of the maths, you can work out the battery equivalent in supercaps by multiplying the battery Ah by 3600 if the supercap and battery are used at the same voltage.

A standard 12v 40Ah lead acid battery is equivalent to a 144,000F 12v supercap.

As you can see, there are significant cost issues in using supercaps as replacements for high capacity uses when replacing even small batteries, although they do obviously at this moment in time have their uses for low power/short surges and quick charge situations. There are also issues regarding supercap voltage. This will droop linearly with the amount of charge taken, unlike a battery which stays pretty stable until near the end of its charge. This means the supercaps will require some sort of voltage stabilisation circuitry in addition to the supercaps.

They will develop over time though, as all new technology does and there is huge potential in the future for high capacity battery replacement but it's probably still quite a way off.

I hope this helps.
mofassair1 year ago
I am working on your project.
But I cannot find LMP2231, MPV30UN, LM385 in my local market. Problem is I am from bangladesh and its difficult to bring those parts from USA.
So, if you can give any alternative of those parts.
jbaker221 year ago
Would you expect a damaged 3000F ultracap to be reliable still if they have 60-80% of their original capacity?
I'm thinking about setting up a minimal solar power system to provide power to a very tiny off-grid house and I'm trying to figure out if there might be a way to make it work without using a battery bank.  I realize that this setup would not provide any power after the sun goes down but the fridge I list below is designed to hold it's coldness through the night.  My idea is to hook about 200 watts of solar panel(s) to a super capacitor and then run a super efficient chest fridge and a washing machine directly off the solar panels through the capacitor. The idea is that the capacitor would help to manage the start up power surge that the electric motors cause and would also smooth out and regulate the power. The fridge would be something like the SunDanzer BFR105.  I would hope to use an energy efficient washing machine too but I'm not sure what the amperage draw would be.  There is one web site here that gives some idea of the typical  power draw during various washing cycles.

Some questions I have are:

1.) Would a 20 Farad capacitor like this be suitable for this application or would I need a larger size?

2.) Am I understanding correctly that a 250 watt solar panel like this  with a Maximum Power Point Voltage Vmpp of 30.7 V would put out a voltage that is too high for the capacitor but that two 100 watt panels like this  in parallel with a Voltage at Maximum Power Point Vmpp of 17.7 would work correctly?

3.) Do you have any idea what would happen if the washing machine attempts to draw more watts for too long a period than are available?  On the pedal power web site it shows that the washing machine draws up to 820 watts at certain times during spin cycles but at other times the draw is much lower.  If not enough watts would be available would the machine simply run more slowly?  It seems that the wash cycle would be ok but that the spin cycle might quickly run the capacitor down.

Thanks for any advice you might have about this idea.
rahulnema2 years ago
hi guys,
this is rahul nema. I am doing my thesis work in which i am making a MATLAB model for Super Capacitor Energy Storage system actually by using this Super Capacitor I am maintaining frequency constant of a 100 KW biomass gasification plant. guys I am very confuse about the rating of the Super Capacitor I mean yet I have not decided what should be the capacity of my Super Capacitor energy storage device. 90 KW load is connected to the 125KVA (100 KW) generator. so please guide me how I proceed in my work..
If you want any other inquiry so plz tell me..
Isn't charging a capacitor with 1A dangerous for you if you take a shock (with the power supply)?
Hi there
No, it is not. At low voltages, if you're charging at high amperage, your only worry would be to burn yourself on the charging conductor. However, when charging at say 5-7v at 1A, it won't get that hot =) You're never going to have to worry about a shock. Remember, your body resistance is in the megaohms, so even if you touch the charging conductor and the ground, you're only going to have 5-7v at uA flowing through you, which is not dangerous at all.
Amazing instructable!

Easy to understand and the best guide about super capacitors I know!
i have accidentally melted a wrench with a full bank of golf cart batteries... oops... o.O i have also designed a fire started with a thing i call zapbox. i has 2 9 volt batteries to charge a few capacitors and then go directly across a thin wire wrapped around the head of a match. perfect for starting fire from a distance!
qoqpop3 years ago
Brilliant ! Thanks for sharing. It has made my mind boggle. That is, what would be the global impact if all cars were fitted with caps instead of batteries. No lead or acid in the environment and light a weight resulting in a further MPG? Is this a dream or feasible?
Un lien est une alternative, il vous laisse libre, vous pouvez l'utiliser ou non. Dès lors que ce n'est pas une fenêtre popup qui s'ouvre automatiquement, il ne provoque aucune gène. Après tout lorsque vous effectuez des recherches internet vous choisissez ce sur quoi cliquer.
La liberté des uns s'arrête à celle des autres et proposer n'est pas imposer.

A link is an alternative, it leaves you free, you can use it or not. Since this is not a popup window that opens automatically, it does not cause gene. After all when you search online you choosing what to click.
Freedom of some stops at the other and offer not to impose.
kbyrne3 years ago
Stupid Me needs a question answered about bipolar caps. A audio circuit calls for a 4.7uf bi polar cap. Is there any difference in types of caps as I have two Bipolar crossover caps. Are all bipolar caps made the same or what gives as I am new to electronics.
MROHM3 years ago
Awesome Instructable Patrick,,,,,,,,,,You know you can never learn enough about Electronics,,,,Enuf Said!!!
If i have 6 caps in parallel, 5 caps at 16v 4700uf and one at 25v 4700uf i know my capacity is 6x4700uf and my charge limit is 16v but what does it output? 16v or 25v?
If it is charged to 16V, it's 16V.

def: A Farad is one Coulomb of charge per Volt.

The capacitance is 4700microCoulomb/Volt, so the total charge on the 25V capable capacitor is the same as the 16V capacitors at 16 V, but with higher voltage, the 25V capable capacitor can squeeze in more Coulombs.
MandingaRes3 years ago
Excelente! Excelente!! EXCELENTEEE!!!!
Me encantó leer este instructable porque además de enterarme bién a fondo sobre los supercondensadores, además está explicado muy didácticamente sin dejar de lado la parte técnica que es tanto o más importante.
A la espera de tus próximos instructables y un consejo: No gastes energías en contestarle a los detractores... (finfun o como se llamen...), solo en seguir brindandonos a los lectores más información util y entretenida.
Gracias y Felicitaciones !!
(Perdón por escribir en mi idioma pero mi inglés es muy malo)
EngineeringShock (author)  MandingaRes3 years ago
Muchas gracias por el comentario tipo. Más por venir pronto. Estoy muy contento de este instructable le ayudó. Por desgracia, no importa cuán bueno es un instructable, siempre hay gente por ahí que quieren romper las pelotas. Yo voy a tener un video instructable pronto sobre cómo hacer una linterna condensador de alto rendimiento. Hay muchas maneras diferentes, pero no tengo un método de diversión. Lo siento si esto se traduce mal. Traductores en línea puede ser muy difícil.

Gracias de nuevo por su respuesta. Siempre es agradable recibir comentarios alentadores como este.

TinkerJim3 years ago
Typo in third to last sentence in Step 5: the word "series" should be "parallel".
EngineeringShock (author)  TinkerJim3 years ago
Thanks. Yes, someone mentioned that. My mistake!
Hope you enjoyed the read =)

Sorry that my typo comment was sent without mentioning that I thought your instructable was very good !
EngineeringShock (author)  TinkerJim3 years ago
No problem at all =) i'm glad you liked it. I had a lot of fun making it.
Hi, thanks for your great instructables, I really liked it. It's very useful to me.
I have a question: why do I have to use capacitors with different voltages when they're placed in parallel?

Hi there!
Thanks for the great question =)
You do NOT have to place different voltage capacitors in parallel. I just wanted to drill into people's heads that if you use different voltage caps in series, never charge to a voltage higher than the minimum voltage rating.

If you're going to place 2 or more capacitors of the same voltage in parallel, like 5x 2.7v 100f capacitors, your parallel bank will be rated for 2.7v at 500f =)

Does that help? Sorry about that. Should have mentioned it.
Ok, now it's all clear! I asked it because it seemed me strange =)
Thank you very much!
Thanks for the instructable! I really need to pick up some super caps for my solar projects. Be more eco friendly.
Hey Josh
Glad you liked it =) if you have any questions down the road, let me know =)
finfan73 years ago
Useful spam is still spam. Flagged.
Remove the ebay store ad step or remove the whole instructable.
EngineeringShock (author)  finfan73 years ago
I've done this for all of my instructables. I can name tons of instructables that do the same; offer links to where parts can be purchased. I can't believe you're spending your time harassing me about a link to my ebay store rather than reading through the instructable. I spent hours of my time to produce this instructable, and all you can think to do is flag me for a link to my ebay store?

If the instructables staff deems that the links to my ebay store are spam, then I will immediately take them down. You're talking about a tiny set of links right at the end that are hardly noticeable, and the only people who would be interested at all would be the people looking to work and experiment with super capacitors.

The links show you where to find the super capacitors shown in the videos. These links take up less than 0.2% of my instructable.
I completely disagree with finfan7. Keep posting links to your websites EngineeringShock.

I'm glad you posted the links above because I like your websites.
I'm glad I looked at your ebay store and I'm glad I checked out your website.

If people like me want to see these links, then they are not spam. It may be a form advertisement, but it is most definitely NOT spam.

Look at all the work EngineeringShock put into this outstanding instructable! I had several misconseptions about series capacitance and I am very glad he put forth the time and effort to educate me. If he wants to put a link in his glowing instructable that promotes his website, good for him!

Besides, no one reading a "Lets Learn About Super Capacitors" instructable isn't going to want to check out a website that sells supercapacitors!

Keep up the good work, E.S.!
EngineeringShock (author)  jensenr303 years ago
Hi Ryan
Thanks sio much for that awesome comment. The first comment I received was....well, as you've seen, it was not flattering. It really got me down. It was really nice to have had someone take the time to write such a thoughtful comment.

I really apprecaite it! I'm glad you like my stores, and I'm glad this isntructable was helpful to you.

Thanks again! I really apprecaite it =)
no problem
I agree that there's nothing wrong with posting the link to his website, and the instructable and the links are both great resources. However, I would have liked to see some other resources for buying parts in addition to the ones run by the author.
First and foremost, I'm not harassing you.
I simply find all forms of advertisement on instructables (and other user generated sites) objectionable.

There are two kinds of linking to sources.
One is linking to the place where the author prefers to get their supplies. This is akin to a friend recommending a restaurant or, if the I'bler is someone particularly well versed in the area, an experienced/expert opinion.

The other kind is linking to the author's own store/webstore/etc. (as in this case) This is a form of advertisement. Using a post on a website as advertising space is spam, no matter how small.

I am not singling you out. Whenever I see anyone doing this I flag it.

I will definitely agree that this is a good resource for knowledge on super capacitors. I read it completely through before ever commenting. But finishing with an ad left a sour taste in my mouth. That's why I commented as I did.
To sum up: you did spam, that is the only thing wrong with the instructable. It is very well written and photographed, but ads don't belong in I'bles.
And what, you aren't a complete @55? If you flag something, you do not have to tell the whole world. You flag it, and if Instructables finds something wrong they will contact the author. You could Private Message him with your concern about it, but you do not need to mention you have flagged it, ever.

Let me ask you this. Do you go around saying to co-workers, "Hey Bob, I reported you the other day for printing your son/daughters essay off on the work printers, which is against company policy."? Of course not, and there is no reason to do it online.
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