Picture of The Forever Rechargeable VARIABLE Super Capacitor Battery !!!
Hi there!

What's all the Hubbub, bub?
This circuit acts as a never-dying, forever rechargeable battery.  If treated properly and with respect, it will live longer than you do! That's right! You will die before this variable battery does!  Eerie, eh?  The circuit employs about $90 worth of circuitry, but it sure beats buying batteries.  I use this circuit every single day when I get home from work to listen to music.  Depending on your input charging method (DC, solar, etc), charging can take only minutes.  With this, I can listen to music out of my computer speakers at high volume for about two hours before having to re-charge.   Use it to charge your cell phone. Use it to power your radio!  Use it as a portable power supply!  Wire it up to a flash light, or use it to power your halloween costume!  The possiblities are endless!  I am selling this in kit form!  See the last page of this instructable for details.

Need 3v?  You got it!
Need 9v? You got it!!
Need 12V?  You got it!!!
Need 34V???  You got it!!!!

The circuit uses SUPER CAPACITORS, as opposed to batteries. Super capacitors are like other capacitors, only they have enormous power storage capabilities.  Capacitors have two storage variables: Maximum charging voltage and capacitance (Measured in Farads).  Capacitance is a measure of how much energy can be stored in a capacitor.  A typical power supply capacitor or audio coupling capacitor would have a capacitance of around 0.0001 farads, which is relatively large.  A super capacitor normally has a capacitance of between 1 to 3000 farads, which make them good substitutes for batteries!  We are going to safely charge 2x 400 farad capacitors in series up to 5.4VDC, and feed that voltage through a DC-DC booster circuit.  We are also going to employ a digital voltage display that will be able to read both the charge on the capacitor bank, as well as the voltage at the output of the DC-DC booster.  Let's go over SOME of the pros and cons of super capacitors, shall we?

1) As long as you don't charge them at a voltage higher than they are rated for, or reverse charge polarity, super capacitors can have charge/discharge cycles of 500,000-1,000,000, or more!
2) If you charge a battery and leave it in the charger, you can deplete battery memory, and it will eventually die.  The super capacitor will STOP accepting any energy once it is full.  
3) The internal ESR (Internal resistance) is extremely small in a super capacitor.  We're talking 0.01 Ohms or less.  A typical battery has an internal ESR or 0.02 Ohms - 0.2 Ohms.   Why does this matter?  If means that you can potentially charge a super capacitor in seconds, providing you have some heavy duty power supplies.  Batteries take longer to charge, and cannot discharge as quickly.
4) Batteries have a shelf life.  If left fully charged on a shelf for years, you will pick it up one day and find it dead.  Not so with the super cap!
5) Super capacitors give off no emissions, while all batteries give off some form of gas.  You can't keep your car battery in your house, but you can keep your super capacitor bank in your house =) 
6) If you cause a direct short along your super capacitors, they will not blow up or be harmed.  They are made to do just that.  However, immense heat will be created along the short, as enormous amounts of current will be very quickly dissipated.  This is also a con, because the user can be burned if not careful.
7) They are environmentally safe.
8) There are so many pros and so few cons, but we don't have time to go over them all =)

1) If you made a super capacitor big enough to replace your car battery, it would likely be 10 times the size.  Super capacitors have lots of energy storage, but need to be banked in series/parallel to achieve battery-like storage.
2) super capacitors normally have very low max voltage ratings, which means that you have to be very careful not to over charge them.  As well, what are you going to do with a 2.5v capacitor?  You have to place a bunch in series to keep doubling the voltage.  However, when you add capacitors in series, you lose capacitance.  The formula for series and parallel banking will be in the final step, so if you have time, have a look =)
3) While you need not worry about shocking yourself, as super capacitors offer so little voltage, you can burn yourself if you create a direct short on a fully charged super capacitor or bank of capacitors. 
4) Super capacitors are more expensive than batteries.

1) The Charging Circuit
2) The Capacitor Bank and the DC-DC Booster
3) The Digital Voltage Display
4) The Parts, the Math and the Conclusions!

If you are interested, most of these parts can be found in my ebay store, which can be found here:  http://www.electroniclessons.com/

Check Out My Improved 1.5A 18 Watt Charger!

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Would you have an idea if I could use a set up like this to power a raspberry pi B+ while I'm away from a wall socket or even in the wilderness? I know the B+ saves power compared to earlier versions but it still takes 5VDC in, and runtime is my main concern.
foxwoodfarm3 months ago

I want to build a little circuit to run 6 or 8 LEDs at night and powered by a solar cell which can charge all day long. I want to store the energy in Supercapacitors during the day and run the lights at night. How many farads do I need to power the lights for a few hours?

NobdoyA3 months ago
I have external usb battery pack that uses 4 3.7v 2400mah batteries, roughly 10.2ah total. what size cap(s) would i need to replace them? The charger has circuit protection 5v 2amp in and out capability.adjustable output.
ed.kaine.13 months ago

I'd like to replace the battery system (6 AA batteries in series) in a Lego Mindstorms EV3 "Brick". Would you think out a kit that I could get from you? It wouldn't have to fit in the same space. Alternatively, do you have something that would have USB power output?

Super experiment. But why do people still use the lithium ion polymer batteries? Why aren't mobile phone manufacturers switching over to super caps?

Capacitors are way bigger than the batteries.

because supercapacitors are ten times less energy dense than batteries. so a supercapacitor with the same capacity as a battery will be ten times larger. supercapacitors are also 10x more expensive.

not to say that it's not being done... SCs have already found their way into power tools. research on SCs is very active. wait for supercapacitor-battery hybrids on your phone in a couple of years


I, your site is very interesting, and I hope to find an anwer for my problem.

I am trying to hook up a switching power supply to a car subwoofer it work find until I increase the volume.

I tryed to install a capacitor 1 farad in paralell and my 500watt supply doesnt startup a all.

I have no problem with an analog supply at 2 amp.

anybody have a solution.

thank you

kani.vetrivel9 months ago

I am building a 3 KW solar panel for my home. I want to use super capacitors instead of batteries. How feasible is it and how do we connect it?

yes, it can be done. just use regulators for charging and for the load.

haseebpk1 year ago

DC-DC converter means 5.4 v to 12 v step up or 5.4 v to 1.5 v step down.

ClownW haseebpk10 months ago

WHy in the name of God would you think that he would want to give you information about this when he is trying to sell the kits?

My God...

hi, the dc-dc booster is a pre-built module. You buy it as-is, ready to use. That's why it's easy. Just have to plug Vin, Vout and GND.

blodefood9 months ago

Could one be built to run a small heater fan? How long could you run a 1500 watt heater fan on a single charge.

Calebescobar1111 months ago
Where the f*ck you found those capacitors??and how much?????
dunnos3 years ago
So... Should I be able to convert Farads to Ah or is that completely wrong? How long am I able to draw how high a currents from this? It's confusing but really seems very much fun :)

Also, how long would these have to charge?
0_Nvd_0 dunnos3 years ago
Super capacitor vs battery comparison:

(5 * "Capacitance" * "Voltage") / 36 = Battery rating in mAh at "Voltage"

I deduced it based on the energy equivalence of the two reservoirs.

Hopefully, it is correct.

Shouldn't it be (5*C*V)/18 ?

0.5 * C * (V ^ 2) = I * V * t

R(Ah) = (0.5 * C * V) / 3600

R(mAh) = (5 * C * V) / 36

This assumes that there is an ideal voltage to voltage converter that keeps the output voltage constant as the capacitor drains.

wow, brilliant instructable.

Can these be setup to run off say 2x ( or more) 1.5w @ 17.5v trickle charge solar panels, plus to output at either USB (5v @1A) or 12v feed? Do you have a circuit diagram ( adjusted values) i can make it into for the solar input and the USB / 12v output.


Keep up the good work

joaqi8231 year ago
This is just MIND BLOWING I don't even know what to do 2500 cycles

Like one of your Super Capacitor Battery to power my HHO Hydrogen System in my Car. On 24 Volt - how much Current could I draw ? Could it handle 15 Amp ?


(Please note I am not the author of this instructable.)

Well... Just check the datasheet of your caps... Some go as high as 2000+ amps! (However, I don't really think their shelf life is anywhere close to infinite... In fact, I believe they are worse than regular batteries.)

Dr.Bill1 year ago

Supercaps Replace A Car Battery !


jamied_uk1 year ago

I have 1 x 65 watt 12 volt solar panel that actually runs around 17 volts and around 1 - 2 amps

However I want / need to increase the amps and lower the voltage going into my charge controller to something like 14 or 15 Volts while increasing the amps a little to at least 5 amps using capacitors / transformer or whatever will be needed

how can I achieve this at the lowest cost possible?

More info you may need I am using a 30 amp (max) charge controller PWM that isnt getting enough amps from the 1 panel to charge 12 volt dc battery (100 ah).
by adding a 25 volt capacitor across the solar panel input on the pwm charge controller this will increase the amps ???

Please note i cant buy another solar panel or buy a mppt charge controller as i cant afford that, so my capacitor idea if it is a good idea we all could use to gain more amps if this is not the case please let me know :)

ASCAS1 year ago

Supercaps FTW! :D

rczegeny1 year ago
Could I make it so charging to 5.4v begins as soon as wall adapter is plugged in, similar to manufactured electronic devices with a charging jack?
lbaracat1 year ago

Hi, this was not clear to me. Is it possible to use this (connect some load on boosted dc output) while it's charging? It sounds obvious, but not for me. =)


cunnr0061 year ago
can this device be altered so that it charges from a 5v solar panel, and produces a constant output of 5v with a power of 1w, would need to discharge over a period of 24 hours
i just heard that the faster you recharge a battery, the faster it will die.
i was interested in super capacitor batteries to charge lithium batteries fastier until i heard that, any inputs on that?
Interesting project - the only feedback I have is you need some sort of bleed across the caps to even out voltage. Series wired caps, even super caps, will charge & discharge unevenly leading to uneven voltages across the caps at full charge. Unless you are very lucky, the difference will continue until the voltage across one exceeds its rated value. Then it will break down causing the other to fail.
scci1 year ago
You sacrificed high power for more usability, I personally prefer the high power fast charging. My charger requires a wall outlet and only works for specific caps and voltages but it charges in 7 seconds.
This is excellent! Do you have a picture of the pcb so I can etch my own board?
jumpjack22 years ago
Thanks for the very clear and interesting description.
I have 2 questions:
- how can I reach 64V in output? Can I connect in series two boosters, or do I need a different output component?
- how can I reach 100A in output? Can I just mount in parallel a dozen of circuits like this? (btw, how much current does it support?)

I'm trying to boost my electric scooter by some supercaps: I have 20 supercaps rated 25F/2.7V each. By now I only need a few seconds boost for testing.

dsuprina2 years ago
What is the maximum current draw for the Super Capacitor battery? I'd like to use this circuit (or something similar) as a means to support an approximately 4A 12VDC draw. Given the ultra capacitors used, how long could such a load be accommodated in the event that the primary power source (AC input) is cut? (I'm looking for a short term -- as in a few seconds -- of UPS capability here.)
ckarthik2 years ago
hi nice work there..

I've a 12 v 5ah battery in my bike.. but it isn't really enough for it.. and gets easily discharged.. i can't upgrade to a higher capacity because of space constraints.. so i would like to use these super capacitors to increase the battery capacity so that collectively I've 9 or 10ah capacity.. any ideas? circuit diagram?
thanks in advance
caranfis2 years ago
I'm looking for a 12VDC, 3A super-capacitor to power up my device for 60seconds. Does this circuit provide this amount of energy?
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