Supercapacitor

The supercapacitor, also known as ultracapacitor or double-layer capacitor, differs from a regular capacitor in that it has a very high capacitance. A capacitor stores energy by means of a static charge as opposed to an electrochemical reaction. Applying a voltage differential on the positive and negative plates charges the capacitor. This is similar to the buildup of electrical charge when walking on a carpet. Touching an object releases the energy through the finger.

We group capacitors into three family types and the most basic is the electrostatic capacitor, with a dry separator. This capacitor has a very low capacitance and is used to filter signals and tune radio frequencies. The size ranges from a few pico-farad (pf) to low microfarad (uF). The next member is the electrolytic capacitor, which is used for power filtering, buffering and coupling. Rated in microfarads (uF), this capacitor has several thousand times the storage capacity of the electrostatic capacitor and uses a moist separator. The third type is the supercapacitor, rated in farads, which is again thousands of times higher than the electrolytic capacitor. The supercapacitor is ideal for energy storage that undergoes frequent charge and discharge cycles at high current and short duration.

Faradis a unit of capacitance named after the English physicist Michael Faraday. One farad stores one coulomb of electrical charge when applying one volt. One microfaradis one million times smaller than a farad, and one pico-farad is again one million times smaller than the microfarad.

Engineers at General Electric first experimented with the electric double-layer capacitor, which led to the development of an early type of supercapacitor in 1957. There were no known commercial applications then. In 1966, Standard Oil rediscovered the effect of the double-layer capacitor by accident while working on experimental fuel cell designs. The company did not commercialize the invention but licensed it to NEC, which in 1978 marketed the technology as “supercapacitor” for computer memory backup. It was not until the 1990s that advances in materials and manufacturing methods led to improved performance and lower cost.

The modern supercapacitor is not a battery per se but crosses the boundary into battery technology by using special electrodes and electrolyte. Several types of electrodes have been tried and we focus on the double-layer capacitor (DLC) concept. It is carbon-based, has an organic electrolyte that is easy to manufacture and is the most common system in use today.

All capacitors have voltage limits. While the electrostatic capacitor can be made to withstand high volts, the supercapacitor is confined to 2.5–2.7V. Voltages of 2.8V and higher are possible but they would reduce the service life. To achieve higher voltages, several supercapacitors are connected in series. This has disadvantages. Serial connection reduces the total capacitance, and strings of more than three capacitors require voltage balancing to prevent any cell from going into over-voltage. This is similar to the protection circuit in lithium-ion batteries.

The specific energy of the supercapacitor is low and ranges from 1 to 30Wh/kg. Although high compared to a regular capacitor, 30Wh/kg is one-fifth that of a consumer Li-ion battery. The discharge curve is another disadvantage. Whereas the electrochemical battery delivers a steady voltage in the usable power band, the voltage of the supercapacitor decreases on a linear scale from full to zero voltage. This reduces the usable power spectrum and much of the stored energy is left behind. Consider the following example.

Take a 6V power source that is allowed to discharge to 4.5V before the equipment cuts off. With the linear discharge, the supercapacitor reaches this voltage threshold within the first quarter of the cycle and the remaining three-quarters of the energy reserve become unusable. A DC-to-DC converter could utilize some of the residual energy, but this would add to the cost and introduce a 10 to 15 percent energy loss. A battery with a flat discharge curve, on the other hand, would deliver 90 to 95 percent of its energy reserve before reaching the voltage threshold. Table 1 compares the supercapacitor with a typical Li-ion.
 

Function

Supercapacitor

Lithium-ion (general)

Charge time

Cycle life

Cell voltage

Specific energy (Wh/kg)

Specific power (W/kg)

Cost per Wh

Service life (in vehicle)

Charge temperature

Discharge temperature

1–10 seconds

1 million or 30,000h

2.3 to 2.75V

5 (typical)

Up to 10,000

$20 (typical)

10 to 15 years

–40 to 65°C (–40 to 149°F)

–40 to 65°C (–40 to 149°F)

10–60 minutes

500 and higher

3.6 to 3.7V

100–200

1,000 to 3,000

$0.50-$1.00 (large system)

5 to 10 years

0 to 45°C (32°to 113°F)

–20 to 60°C (–4 to 140°F)

Table 1: Performance comparison between supercapacitor and Li-ion

Courtesy of Maxwell Technologies, Inc.

Rather than operating as a stand-alone energy storage device, supercapacitors work well as low-maintenance memory backup to bridge short power interruptions. Supercapacitors have also made critical inroads into electric powertrains. The virtue of ultra-rapid charging and delivery of high current on demand makes the supercapacitor an ideal candidate as a peak-load enhancer for hybrid vehicles, as well as fuel cell applications.

The charge time of a supercapacitor is about 10 seconds. The charge characteristic is similar to an electrochemical battery and the charge current is, to a large extent, limited by the charger. The initial charge can be made very fast, and the topping charge will take extra time. Provision must be made to limit the initial current inrush when charging an empty supercapacitor. The supercapacitor cannot go into overcharge and does not require full-charge detection; the current simply stops flowing when the capacitor is full.

The supercapacitor can be charged and discharged virtually an unlimited number of times. Unlike the electrochemical battery, which has a defined cycle life, there is little wear and tear by cycling a supercapacitor. Nor does age affect the device, as it would a battery. Under normal conditions, a supercapacitor fades from the original 100 percent capacity to 80 percent in 10 years. Applying higher voltages than specified shortens the life. The supercapacitor functions well at hot and cold temperatures.

The self-discharge of a supercapacitor is substantially higher than that of an electrostatic capacitor and somewhat higher than the electrochemical battery. The organic electrolyte contributes to this. The stored energy of a supercapacitor decreases from 100 to 50 percent in 30 to 40 days. A nickel-based battery self-discharges 10 to 15 percent per month. Li-ion discharges only five percent per month.

Supercapacitors are expensive in terms of cost per watt. Some design engineers argue that the money for the supercapacitor would better be spent on a larger battery. We need to realize that the supercapacitor and chemical battery are not in competition; rather they are different products serving unique applications.Table 2 summarizes the advantages and limitations of the supercapacitor.
 

Advantages

Virtually unlimited cycle life; can be cycled millions of time

High specific power; low resistance enables high load currents

Charges in seconds; no end-of-charge termination required

Simple charging; draws only what it needs; not subject to overcharge

Safe; forgiving if abused

Excellent low-temperature charge and discharge performance

Limitations

Low specific energy; holds a fraction of a regular battery

Linear discharge voltage prevents using the full energy spectrum

High self-discharge; higher than most batteries

Low cell voltage; requires serial connections with voltage balancing

High cost per watt

Table 2: Advantages and limitations of supercapacitors

Comments

On December 15, 2010 at 12:45am
gups wrote:

good

On January 31, 2011 at 7:40am
Ibrahim wrote:

I am highly impressed and interested in this topic, How I wish I have a full time research center I would have ventured into its advanced pioneering.

On February 11, 2011 at 7:40am
nick wrote:

I am highly impressed and interested in this topic. I would like to know how does happen the charge and discharge in a double layer supercapacitor. What happen in the eloctrodes (reactions and ion moves) what is the role of the seperator and of the electrolyte.

On February 20, 2011 at 8:27am
Brent wrote:

I would like to know how an ultra capacitor helps or hurts an older battery.

On February 23, 2011 at 4:50pm
Bill wrote:

Nice summary.
Maybe low voltage DC-DC conversion could be used to produce constant output voltage?

http://electronicdesign.com/article/power/ultra-low-voltage-dc-dc-converter-ics-a-br-font-cl.aspx
http://www.electrochem.org/meetings/scheduler/abstracts/214/0690.pdf

On February 26, 2011 at 12:44am
spuzzdawg wrote:

The second paragraph incorrectly uses mF to represent microfarards. This should be corrected to uF.

On March 1, 2011 at 3:36pm
Cadex Electronics Inc. wrote:

@spuzzdawg: Thanks very much, I have corrected that.

On March 2, 2011 at 1:35am
Joshua Okunor wrote:

Fantastic. Is this an innovative idea? What are the application areas?


Joshua

On March 7, 2011 at 7:01am
html tools wrote:

Capacitors are used in various ways, with some of them designed for high-frequency circuits. Others are made specifically to handle larger amounts of voltage. Capacitors of various sizes and designs are used to tune radios, in clocks and electronic counting devices, in sensitive medical equipment and even in cars and electric vehicles.

On April 4, 2011 at 2:16pm
jim wrote:

Can Imuse a super capicity battery in place of a deep cycle 12 volt? and how isi it charged?

On April 6, 2011 at 12:16pm
Kevin wrote:

I would be interested in using ultracapacitors in an EV, in conjunction with my battery pack.  I’m guessing I would wire them in series and in parallel with my battery pack.  I have heard of a guy in Australia who has used ultra caps in his lead acid EV that has extended his battery life out to 10 years now.  I want some of that!

On April 7, 2011 at 3:44am
Juha Kuusinen wrote:

Just wanted you to add that there are new generation of supercapacitors coming

www.tplinc.com

On May 5, 2011 at 2:41am
Ralf wrote:

@Kevin
You might wanna check this out, perhaps this is what you think you heard:
http://www.csiro.au/science/Ultra-Battery.html

I doubt wether a DIY retrofit of super caps to a lead acid EV is feasible or safe. One would have to connect about 5 super cap “cells” in series over each lead acid battery if I’m not mistaken. Without some form of cell balancing and management, you’re heading for disaster.

On May 6, 2011 at 10:11am
Roberlanio Melo wrote:

Referring to the last paragraph: is possible perform a marriage between the batteries and supercapacitors in a harmonious way in order to increase battery life. Adopting a hybrid system. Consult the paper “Power and Life Extension of Battery-Ultracapacitor Hybrids” by R. A. Dougal, Senior Member, IEEE, Shengyi Liu, Member, IEEE, and Ralph E. White.

On May 6, 2011 at 11:10pm
bob wrote:

Excellent article but it leaves out the most interesting thing: the research which indicates that a supercapacitor in parallel with a lead acid battery greatly extends batterly life also increases its effective capacity (when used in electric vehicles). An unspoken downside to the current crop of Li-Ion powered 2 wheel vehicles (at least) is the short life and expensive replacement of the battery - perhaps ten times the cost per houir of the electricty used to charge it.

On May 15, 2011 at 3:06pm
Bob Burger wrote:

Is anyone in the United States working on combining Li-ion and supercapacitors?  Is it possible to create a small/crude model for a lay person with some directions?

On May 23, 2011 at 9:36pm
Tommy P wrote:

Does double-layer capacitor technology have a future in consumer electronics, possibly as a replacement for the antiquated Li-ion energy storage systems used in cell phone batteries?
Also, is “graphene” an example of DLC? I’m confused.
Any comments would be very much appreciated. Thanks.

On June 9, 2011 at 4:10am
Fredllfixit wrote:

I think we should remeber that supercapacitor development is more or less in the middle of it’s “curve”. I’ve no doubt we are yet to see many improvements, especially when one considers the ‘drive’ behind it. I mean CO2 pollution control and the need to reduce dependance on fossil fuels. (Supercapacitors can be charged by wind-turbines and nuclear power stations). Let’s not forget the huge political significance if our cars DON’T need petrol or diesel to propel them!

On July 19, 2011 at 4:22am
sagar wrote:

ho can i buy this one?????

On August 2, 2011 at 12:14am
Sudha wrote:

Very interesting!
If any method using supercapacitors and batteries/dc-dc converters to replace the backup power supply system, please forward

On August 2, 2011 at 7:12am
jim wrote:

I have patent pending technology that increases agm 12 volt output by 8-11% with no outside energy, I am wondering if this can be done with supers?

On August 26, 2011 at 8:54am
Gaurav singh wrote:

I am highly interested towards this topic and i am currently working on it , i require a very kind support from people around for its improvement basically in the field of its improvement on its disadvantages can the right direction be suggested by you ?

On August 26, 2011 at 10:07am
Fredllfixit wrote:

If you are going to connect a bank of supercapacitors across a 12v lead-acid battery for experimental purposes, you should observe the following:—

1) Each capacitor in the series chain cannot have more than 2.5 volts across it. Therefore some kind of balancing device such as zener diodes should be used across each capacitor in the chain. Remember a lead-acid 12v battery has 14.4 volts across it under charging from a typical car alternator.
2) You can’t just connect a supercapacitor across a battery as the battery will see it as a short in the 1st. few microseconds, or even a milisecond or two of charging the capacitor from the battery. This could blow up the leads, or set them on fire depending on how big the supercapacitor was. The circuit will need some resistive limiting until the supercapacitor has charged.
3) If you are wanting to save money in some way by using supercapacitors, forget it. A 1-farad 16volt supercapacitor will cost anything between £50 and £75, depending on sourcing. If you were thinking of 100 farads…..
4) A supercapacitor won’t store anywhere near the capacity of a lead-acid. But it will supply an instantaneous current far in excess of the battery, making volts-drop during cranking an engine to start it very much less, as an example.
5) A battery will supply a ‘fairly’ constant voltage during it’s discharge cycle; a supercapacitor won’t. It falls linearly with the discharge period. Therefore, some equipment won’t work after a certain voltage fall when there is still lots of energy in the supercapacitor. Sophisticated power-supply circuits are needed to use ALL the energy, or say, 90% of it from a supercapacitor; A dc-dc converter might be appropriate.
Hope this helps the students.
Fredllfixit.

On September 28, 2011 at 5:44am
mahesh wrote:

I am connecting 132 capacitors(2.5V) in series with voltage balancing resistors. Please suggest one charging topology for this capacitor bank(350V) amomg boost converter and buck boost considering the minimum charging time slao. Pls help..

On September 28, 2011 at 12:50pm
Fredllfixit wrote:

Voltage balancing resistors won’t do. They will discharge the capacitor soon after charge if they are of low enough resistance to work, and a high ohmic value of resistor will not ‘balance’ the voltage on each capacitor cell. Simple resistors are not voltage-sensitive.
You need as many zener diodes at 2.5volt working as there are capacitor cells. FYI, the zener has near infinite resistance with reverse voltage as usual with a diode*. But it won’t conduct until 2.5volts exist across it in the conducting direction, i.e. when you have deliberately chosen 2.5volt zeners. I could not begin to suggest a power rating for the zeners, but it’s going to be high, and expensive.
However, LEDs also ‘fire’ at 2.5volts, and if your supercapacitors are fairly small, there may be some possibilities here. However, don’t be surprized if a supercapacitor blows them up!
*Any semiconductor diode will eventually breakdown if you put enough voltage across it. This is the “avalanche-effect”.

Also, common silicon diodes have 0.7 volts-drop in the conducting direction. Four of these in series wont conduct until 2.4volts exists across them. These diodes are VERY cheap!
Fredllfixit.

On September 28, 2011 at 12:52pm
Fredllfixit wrote:

If you rectify british mains into a reservoir capacitor, you get 330 to 350volt DC. Will that do?
Fredllfixit

On October 5, 2011 at 11:12am
mahesh wrote:

Thanks Fredllfixit…i ve already made the capacitor bank..What i need is a good charging methodology without using micro controller..please help

On October 5, 2011 at 12:01pm
Fredllfixit wrote:

I should think the only charging method will be to ensre it produces the design voltage, and has a series limiting resistor to prevent the charger from seeing the suparcapacitor as a ‘short’ for the first few seconds. The value of the resistor you should be able to calculate easily so as not to overload the current rating of the charger intiially
Fredllfixit..

On October 5, 2011 at 10:15pm
mahesh wrote:

Thanks Fred..The capacitor bank voltage here is 350V.So kindly suggest one charging method ..Like boost converter, Buck-boost etc…I wud be using one inductor for making this DC-DC converter..Hoew about charging the bank using a slightly higher voltage till it reaches the bank voltage..?

On October 6, 2011 at 1:21am
Fredllfixit wrote:

If you are building a charger from scratch to charge supercapacitors, prob. the best advice I could give would be to contact the capacitor manufacturers for their advice. Seems sensible after all, as they will have already done any specialized research in the matter. Usually these manufacturers are VERY co-operative with students using their own products. Liason with their people can often save a lot of time, and you will have ‘spin-off learning’ to boot. Making your own smart charger is hard work.
I would comment that I’m now wondering why such a high-voltage combo of 350volt? Are you propelling a car with it?
Fredllfixit.

On October 6, 2011 at 10:53am
mahesh wrote:

thanks Fred..i ll try contact the manufacturer..

On October 6, 2011 at 1:19pm
Rory wrote:

hehe I think Mahesh is designing energy storage for a solar power facility wink

On November 25, 2011 at 6:02am
Alex Robles wrote:

Trying to get some help.  I am building a 72v vehicle with 24v in Super-Capacitor and 48v in AGM batteries.  I f I provide a constant charge to the bank while the 72v motor is in use what would anyone recommend; do I have them wired in parallel or in series?  What other device, diodes or equipment should I have installed in order avoid destroying any of the banks.  The DC charge can supply a constant voltage of around 100v.  Any assistance will be greatly appreciated.  I am just a retired Navy Cryptologist, now trying to invent a homemade vehicle.  Thank you in advance.

On January 1, 2012 at 10:37am
UncleBuck wrote:

I’ve been playing about with the same thing… hehehe, blew quite a few this along the way.

I’m trying to use the supercapasitors to flash charge the car and allow it to trickle feed the batteries to keep/charge them up…

In turn filter some power off to run a small genie to keep the batteries topped up and with the help of small genies on the opposite side of the motors on each wheel hope to keep it going from 6-8 hours before a charge.

On batteries alone a BMW X5 big beast,  lasts 2.5 hours. Hoping to get that to 6 hours… EASY EH hehehe…

Great to know others are playing about too…

I’ll post more if I achieve longer lasting power….

On January 5, 2012 at 1:05am
Bhuvana wrote:

can you pls send me about the details about the super capacitor energy storage system mainly its capacity.your paper is very good.

On February 6, 2012 at 6:38am
alam wrote:

i am trying to charge two supercapacitors (52F each) connected in parallel and aim to calculate its resistance and inductance. can anyone suggest me any charging methods and the calculations required to find the parameters?

On February 8, 2012 at 5:55am
Jim S wrote:

I need supercapacitors to hold a chrge for a 15 hp dc motor 465 volts. I need to hold the charge for .5 seconds when the motor lost power.
I need .5 seconds pass through. Any ideas?

Thank you
Jim

On February 29, 2012 at 8:25am
Pradeep wrote:

Sir

I want to know how to calculate ESR value for 2.7 volt 25 F 6 no series ultra capacitor.

On March 8, 2012 at 7:13pm
Josh wrote:

You seem to know a lot about capacitors , so my question is that I’m making a rail gun, and I need to know what will make it the strongest( it’s magnetic polarities) the volts or farad? If it is farad should I get 1 microfarad or 1 farad? I need it strong.

On March 23, 2012 at 7:53am
Karan Thadhani wrote:

Once the Ultra capacitor is fully charged then how much time it will work without any external supply?
And if it is discharging in few seconds then how it can replace a battery while battery is discharging in2-3 hours??
And suppose i have to replace my vehicle’s battery with an ultra capacitor so how should i need to connect??
What is the circuitry to connect an ultra cap?

On March 23, 2012 at 10:58am
Shubham yende wrote:

I have to make mobile battery charger.
If here we charge the capacitor with the help of dc generator then our input is zero but output get through charging.

On April 6, 2012 at 6:20am
Joseph wrote:

I suspect that the best use of super caps in an electric vehicle is for regenerative braking.  It takes a long time to charge a battery.  It takes very little time to charge a cap.  So when doing regenerative braking you need to get the electricity generated into something quickly.  That means a super cap.  Then let the cap charge the batteries.  This uses the caps in a role they do best, a reservoir for charge.

On July 12, 2012 at 12:10am
Ion Livas wrote:

There is a third type of energy accumulator that is entirely mechanical and devoid of any toxic materials.
This is the Mechanical Battery that stores energy in a torsion spring, based on the clock-mainspring principle.
A torsion spring 60 mm wide, 1 mm thick and 300 meters long wound around a 950 mm Drum, can store 10Kwh of power. The power can be retrieved at will as required.
There is to limit to the size that a Mechanical Battery can be made.
Ideal for Solar Panels/Boats/Ships/vehicles and any other device requiring energy storage and recovery.
The Patent Documents describing the invention can be had on request.
Ion Livas
ionlivas@gmail.com

On September 7, 2012 at 5:18am
pramod wrote:

yes offcource m goin to make a supercapacitors with nanomaterial and polymer composite.great area of research.

On September 7, 2012 at 8:14am
Ion Livas wrote:

I have written to you already about this invention, as you can see above.
Please do not mock the invention of “The Battery of the future”, with references to antiquated hyperbole.
We are talking about a cheap Battery that can pack MILLIONS of kWh in a tiny space while all of it is totally MECHANICAL.

If you want to know more, contact me at ionlivas@gmail.com and I will give the ride into the future, arising from the SIMPLEST MECHANICAL breakthrough.


The “MECHANICAL BATTERY”. has been called “the Battery of the future”, as it is both minuscule and featherweight, compared to present day conventional batteries.
For example, a 120 kWh unit is only the size of the wheel of a motorcar and weighs no more than 60 Kilograms.
Furthermore it is:
1. Ecological, as it is TOTALLY mechanical.
2. It needs no maintenance.
3. It does not degrade when idle.
4. It is easy to manufacture.
5. It is dirt cheap.
6. There is no limit to the size of a Mechanical Battery.
7. It can be used to power vehicles, propeller planes, boats, even Submarines, as well as to Store the Energy produced by the Sun.
The ‘natural’ mass utilization of the MECHANICAL BATTERY, where it would be of greatest benefit and advantage, would be in the Auto Industry.
And as all the above claims have to be seen to be believed, a Representative of yours will be welcome to visit, to be shown and explained what the Mechanical Battery looks like and how it works.
Looking forward to hear from you,
Ion Livas
ionlivas@gmail.com
Freatidos 27
18536 Piraeus, Greece
Tel: +30-213-009-945
Cell: +30-6940-507077

On October 23, 2012 at 5:44pm
Carl wrote:

I have a couple of 2600 F caps on order. I am in the process of building a micro processor controlled Super Cap charger that will not allow cap to exceed the max operating voltage.
Will Super Capacitors eventually replace batteries? Maybe use with lead acid batteries to prolong their life? I will be conducting a few experiments and will post my result here, soon.

On October 23, 2012 at 6:12pm
Bill wrote:

Hello Carl,

Will Super Capacitors eventually replace batteries?

Possibly, but output voltage versus charge is different. Batteries are pretty well constant output voltage until nearly flat. Not true for supercaps.

Maybe use with lead acid batteries to prolong their life?

Very good application.
Supercap/Battery combination is good where initial surge currents are high. So could use a battery with lower CCA rating.

Bill

On January 12, 2013 at 1:24pm
Carl wrote:

Wow! It has been 3 months since my last post. I have been busy installing a grid tie solar system on my home and it is now in operation. The microprocessor controlled super cap charger I built operates very well. I have a couple of 2,600 Farad super caps I have been playing with. These guys are bad boys! I charged one of these and operated a red led 2.3 volts@ 20 ma. The led emitted light for 2 days before dimming. My next project is purchasing a few small ones for flashlights and for cordless drills and maybe a cellphone.
Not quite ready to install a bank in my automobile, but i`ll get there. I will post my results as progress continues.

On January 14, 2013 at 7:52am
Carl wrote:

I would like to make a clarify the experiment regarding my previous post. The super cap I was using to drive that red led had no current limiting resistor. The super cap is rated for 2.5 V. It was charged to 2.4 V. The led ran very warm. drawing more than 20 MA of current. I did not measure the current draw.That was not a good test.

Here is a better test:
I connected two Maxwell 2.5V 2,600 Farad Ultra Capacitors in series with a white 20 MA led with a 56 ohm current limiting resistor. I measured .2 voltage drop across the series connected capacitors. This white led has been on for 38 hours and it seems to be as bright as it was when I connected it. I do not have a light meter to measure the intensity. I ordered a couple more Super Capacitors, the size of D batteries. The caps on order are Maxwell 350 Farad @ 2.7 volts. I will use these to construct a flashlight. Any idea what will be better to use, one of the caps with a charge pump or both with a current limiting resistor?

On January 15, 2013 at 10:54am
Carl wrote:

FORMULA NEEDED!
Will someone provide a formula for calculating the amount of current a Supercapacitor will deliver at various loads? I sure would appreciate it.
Thank you!

On January 20, 2013 at 6:13am
Carl wrote:

TV REMOTE CONTROLLER OPERATES ON U CAPS!

A tv remote controller utilising 2 AAA batteries was replaced with 2 parallel U CAPS.
The caps were installed 3 days ago and still operates perfectly. Charging time to full charge is about 20 sec. Not bad, not bad at all! No more batteries for this remote!

On January 23, 2013 at 6:28am
Carl wrote:

US Army lab ties up with MU to build nano-hybrid supercapacitor

The United States Army Research Laboratory has joined hands with a Mumbai lab to develop nano-hybrid supercapacitors. These long-lasting power storage devices would be a cheaper and greener alternative for use in hybrid vehicles.

On January 29, 2013 at 11:39am
Carl wrote:

Supercapacitors not ready to replace batteries.

Supercaps will replace batteries if the device draws small amounts of current. For example, a few milliamperes. Take for example, a TV remote controller that operates on a couple of AAA batteries, it is possible to replace them with U-Caps. I have proven that. However, if a cordless screwdriver batteries are replaced with U Caps, you would be very lucky to drive in a couple of screws. Take a 1W LED for example, 2.7 volts @ 320MA driven by 2, 2.7 V series connected 350F U-Caps with a total capacity of 175 Farads. Light output drops dramatically after 30 minutes. However, if the current limiting resistor connected to the LED was shorted after a 30 minute period, Yeah, bright light again, but for only a few more minutes. I also connected a 2.7 Farad U-Cap to a DC to DC inverter driving the same 1W LED. Again, I experienced the same results with the caps in series. 30 minutes of bright light. Nothing close to what Ni-Mi, Nicads or alkaline batteries will do. However, the caps have one thing going for them, and that is they can be charges extremely fast! SuperCaps have a ways to go, but I believe as resarch contunues, they will replace batteries and render batteries obsolete! I love Supercapacitors and will continue using and experimenting with them. Oh, that remote controller is still hanging in there with those u-caps installed!

On January 30, 2013 at 8:55am
Carl wrote:

Taiyo Yuden’s New Hybrid Lithium Ion Capacitors Provide Energy Densities up to 10 Times Greater than EDLCs

Schaumburg, IL - Taiyo Yuden’s new Cylindrical Lithium Ion Capacitor (LIC) offers extremely large energy capacitance and high reliability. Combining the strength of lithium-ion secondary batteries with conventional Electric Dual Layer Capacitors (EDLC)s, this next-generation energy device offers an energy density 4 to 10 times greater than EDLCs.

On February 1, 2013 at 8:01pm
Carl wrote:

1W LED U-CAP FLASHLIGHT

2 Maxwell 2.7V 350 Farads D Cell U-caps connected in parallel, for a total capacitance 700 Farads, driving a LTC3490 350MA LED driver. The LED current was limited to 320MA. The LED was very bright until the U-CAPS voltage dropped to .8 volts. The Led driver shut the led off, as I stated, at .8 volts. The brilliant light from the LED last for about an hour before shutoff. I noticed no dimming from turn on to shutoff.

On February 5, 2013 at 7:51am
Carl wrote:

SUPERCAPACITOR VOLTAGE DROP

The major problem with U-Caps is voltage drop! The greater the load, the faster the voltage drops. That is the major reason as to why U-Caps has not replaced batteries. U-Cap reachers and engineers are working on developing U-Caps that will overcome this problem. However, there is a means to overcome this problem to a reasonable degree, and that is to employ a DC to DC Converter. I have been searching for days trying to find equations to determine the length of time a U-Cap will last per given load. Most of the formulas I have found are incorrect. Maxwell Technologies has an excellent application note that has the equations to correctly size the U-Caps for both series, series parallel and parallel connections to fit the application you desire.
I will later upload that application note for those that are interested.

On February 7, 2013 at 8:15pm
Carl wrote:

MAXWELL TECHNOLOGIES APPLICATION NOTE ON SIZING U-CAPS

The Maxwell App. note on sizing Ultracapacitors is too lengthy to upload here. However, here is a link for anyone to study. Copy and paste into your browser.

https://docs.google.com/viewer?a=v&q=cache:fR0Nxng5ZXUJ:www.maxwell.com/products/ultracapacitors/docs/10073627.3_how_to_determine_the_appropriate_size.pdf+maxwell+sizing+supercapacitors&hl=en&gl=us&pid=bl&srcid=ADGEESiKwoGbR2pz12nhIRdziAiVd4Uc_LXEFE14RyWHTvofffG7Ct2u5nuijZANwTzSzmw7_PHrNxistptTh9PS6XXdAGFEwvEELfnAaqv0vJIrjXwlHIEL3ZgWFawUwdEj-SKFhyK_&sig=AHIEtbR73EHhMK2kqAMoZzXVU56xRrHIiw

On February 10, 2013 at 9:27am
Carl wrote:

DSP PORTABLE AM/FM RADIO OPERATES ON MAXWELL ULTRACAPACITORS

The radio operated on 2 AA batteries, but now has U-Caps installed. It was necessary to modify the battery compartment to install the caps for the compartment cover to be replaced.

On February 13, 2013 at 5:56am
Carl wrote:

SKIL, 4,8V 1/4” CORDLESS DRILL OPERATING ON ULTRACAPACITORS

The Caps are not installed in the compartment, but will be shortly. It seems to provide plenty of torque. Later, i`ll post current draw, voltage drop,duration and other data.

On February 13, 2013 at 9:16am
Carl wrote:

SKIL, 2.4v CORDLESS DRILL CONTINUED

I stated in a earlier post that you would be lucky to insert a couple of screws with a cordless screwdriver powered by Supercapacitors. However. I was wrong! It is possible to insert quite a few! The U-Caps I used for this SKIL screwdriver are too large to place into the battery compartment, therefore it was necessary to order a few smaller Maxwell U-Caps that will fit into that compartment. Those Caps should be here buy the beginning of next week. I`ll provide the data on this after I receive and install them.

On February 13, 2013 at 9:36am
Carl wrote:

13 Feb 2013 |  Germany
All eyes on Supercapacitors

Supercapacitors Europe 2013 in Berlin, adds a global dimension too with best-in-class speakers from Asia to America including leader CAP-XX from Australia, Graphene Frontiers from the USA and Shanghai Shi Long High-Tech of China, Elbit Systems from Israel and HEL Ltd from the UK. These speakers will detail how why and what next, notably in replacing batteries and analysts IDTechEx present the latest ten year forecasts. No other event has such a comprehensive coverage of the component that is changing the world, the supercapacitor, including its technologies from carbon nanotubes to graphene in this session.

On February 14, 2013 at 5:39pm
Carl wrote:

                                  CORRECTION!

I inadvertently called the Skil 4.7V 1/4” cordless screwdriver a cordless drill. It is not a cordless drill, but a cordless screwdriver My apology for the error. The Supercapacitors to replace the Nicad batteries in that screwdriver is scheduled for delivery Monday, Feb. 25th. I`ll keep you posted.

Very soon I will be replacing the lead acid battery in a Jeep Cherokee. The battery will be replaced with a bank of Maxwell 2.5V 2,600 Farad Supercapacitors. The Supercaps will not be used in conjunction with the lead acid battery, but will completely replace it.
Many thanks to Maxwell Technology for providing the formulas for calculating Supercapacitor sizing.                                 

On February 15, 2013 at 10:00am
Carl wrote:

Skil 4.8V 1/4” Cordless screwdriver now operates on Supercapacitor

I found a couple of 100 Farad 2.7V S-Caps kicking around that I forgot I had. Dimensions:
Capacitor Body:  (ΦD) 22.0±1.0mm x (L) 50.0±2 .0mm
Capacitor Leads:  (Length) 6.8±0.5mm x (Width) 1.5/2±0.1mm (Lead Spacing) 10.0±0.2mm. It was necessary to slightly modify the battery compartment to reassemble the unit. Although the driver states 4.8V, I found it to operate on 2.6V and below with a minort decrease in speed, but maintained good torque. I felt it to be unnecessary to measure the current draw. I would guess the current draw to be around 200 mills or slightly more, under no load. Operating time with no load, about 3 minutes.
Charging time, just a few seconds.

On February 19, 2013 at 2:06pm
Carl wrote:

                  SUPERCAPACITOR TO THE RESCUE!

BRAUN CORDLESS TOOTHBRUSH POWERED BY SUPERCAPACITOR

While studying supercapacitor equations, my daughter asked me for batteries to install in her toothbrush. Unfortunately I did not have any charged. I asked her for the time required to brush her teeth, and she responded, about 1 to 1.5 minutes. There was enough room for a Maxwell supercap! After testing, i am now in the process of installing.

On March 3, 2013 at 6:53am
Geser wrote:

That is amazing. But I think also we need research different kind of energy. Not AC or DC. We saw in nature fe: Fish, Organic grass etc. Then we can see more possibilities for charge and store super-energy. Is that Air-energy or Radio-energy?

On March 5, 2013 at 1:58pm
Carl wrote:

                  SUPERCAPACITOR POLARITY REVERSAL

While conducting some experiments with 3 parallel 2.7V 25 Farad caps, for a total of 75 Farads, I accidentally had the polarity from the charger reversed. The charger was connected to the caps using test leads. After charging, I found the polarity of the negative and positive leads of the caps completely reversed. In other words, the negative was positive and the positive was negative. I would not recommend doing this, but it may have applications for some specialised task.

On March 8, 2013 at 4:49pm
Carl wrote:

                    GRAPHENE SUPERCAPACITORS

WHAT IF YOU COULD CHARGE YOUR VIDEO CAMERA, CELL PHONE, TABLET PC, OR A LAPTOP COMPUTER IN 30 SECONDS AND HAVE IT WORK ALL DAY LONG?

According to UCLA inorganic chemistry professor Ric Kaner, whose research focused on conductive polymers and next generation materials.
It states that while developing a new way to generate graphene — the same material used in carbon nanotubes — Kaner’s team made a serendipitous discovery: The new graphene supercapacitor! I sure would like to get my hands on a few of those!

On March 14, 2013 at 2:41pm
Carl wrote:

Ionova Technologies Announces Breakthrough In Ultracapacitor Value Proposition

Zinc-Ion ZIP-Cap™ Leverages Existing Battery Facilities To Produce Power Storage With A Dramatic Improvement In Cost and Energy

FREDERICK, Md., March 14, 2013—/PRNewswire/—Ionova Technologies, Inc. today announced it has achieved a breakthrough in the value proposition of power storage.  The zinc-ion based ZIP-Cap™ is expected to provide a 25-fold reduction in build cost, and a 5-fold increase in energy density – without the ultra-pure materials or expensive “dry-room” facilities that are necessary to build today’s ultracapacitors.

On March 22, 2013 at 6:54am
Carl wrote:

        SUPERCAPACITORS IMPROVING FASTER THAN BATTERIES

Supercapacitors replace lithium-ion batteries. Lithium-ion batteries replace nickel metal hydride and lead acid batteries. There are side stories of course. Some supercapacitors replace electrolytic capacitors and others create new applications.

On March 23, 2013 at 2:55pm
Carl wrote:

WORX GT WG151 18-VOLT ELECTRIC TRIMMER/EDGER POWERED BY MAXWELL SUPERCAPICATOR BANK

6 Maxwell D Cells, 2.7V, 350 Farad Supercaps connected in series parallel. Total capacitance 1,050 Farads. Voltage 8.1 Volts. A DC-DC inverter is employed to boost the voltage to 18 volts. Run time approximately 20 minutes. Charge time 2.25 minutes.

On March 27, 2013 at 8:37am
Carl wrote:

PANASONIC KX-TG6512B DECT 6.0 POWERED BY SUPERCAPACITORS

The phone was powered by 2, AAA series connected 1.2V 500 mAH Nii-MH batteries. The NICHICON supercaps are 2.7V 22 Farads each, connected in parallel. It was necessary to use a DC-DC inverter to compensate for voltage drop. the caps are a bit too large to be placed in the battery compartment. Therefore, I shall order a few smaller ones. What is strange, is the display states, use rechargeable battery. Ha ha. It operates perfectly though.  To keep this charged, the base unit power supply will require slight modification. Follow-up on this later.

On March 27, 2013 at 4:04pm
Carl wrote:

          PANASONIC KX-TG6512B DECT 6.0 CONTINUED

44 farads at 2.7V is 160.38 Joules or 118.8 Coulombs and that corresponds to .033 Ah or 33 mAh. The phone draws .018 Amps or 18 mA on standby. With the phone off hook, the current draw is .132 Amps or 132 mA. On standby, the phone will last slightly under 2 hours before it bites the dust. When the phone is off hook, it will last 15 minutes before it dies. After I did the calculations I tested the phone to check if my math was correct. Well, the phone lasted 11 minutes off the hook. Why not 15 minutes? Because the inverter is only 95% efficient. Also, the inverter shuts the phone down when the Cap voltage reaches .5 volts. The caps are too large to fit into the battery compartment. I could cut the compartment to fit the caps into, but there is a problem doing that. On the left side of the pc board under the battery compartment, there is a small Electrolytic cap. I believe it was a 10µF. Also, on the right side under the compartment is a headphone jack. I could remove that cap and relocate it and remove the headphone jack and bypass its connections. If I did that, I could modify that compartment and install the Supercaps. Is it worth it? I believe it is not. No, I will not attach a large Supercap on the side or back. It would be cool to have a 1,500 Farad cap the size of a AAA battery. Yeah, right!

 

On March 28, 2013 at 11:01am
Carl wrote:

                      PANASONIC KX-TG6512B CONTINUED

Problem with mounting Supercapacitors solved! I have decided to use 4, 22 farad parallel connected Supercaps. I am having a new battery cover made that will allow the DC-DC converter, (not inverter, as I stated earlier) along with the Supercaps to be placed in the battery compartment. The new cover will extend from the phone by 1/4 inch. Now, the phone will have prolong standby and off hook time. On standby, the phone will last 3 hours and off hook will be 30 minutes. I have not measured the current supplied by the phone base charger. I suspect it is only a few mills. I am sure it will require some modifications. I may place a DC jack on the end of the phone for connection to my Supercap charger. If so, charge time wil be just a few seconds. My apology if I sounded rude in a previous statement by stating I will not place a large capacitor on the back or side of this phone. It would not look professional.

On May 6, 2013 at 2:23pm
SB20 wrote:

Car, you are a madman!  I meant that in a very good way.  smile

On May 11, 2013 at 12:04pm
SlithernSnake wrote:

I’ve been experimenting with the 2.5v 2600F Maxwell caps by putting six in series to make a 15V max. pack & putting those packs in parallel & running them from 14V down to 11V with a 1500 watt inverter connected to them. I’ve been able to run a small microwave for about 3 or 4 minutes and a small beer fridge for 9 minutes, a 9 watt led bulb for about 40 minutes, etc. I dont have any balancing circuitry on them & wouldn’t think it would be necessary since I’m not charging the packs past 14 volts. Was even thinking about adding a seventh cap into the series strings so they could go up to 17.5V without damage to act as balancing protection without zenner diodes. I’ve got 24 caps in this setup so far & would like to parallel some more packs in line but aren’t sure if I’m headed for disaster by having too many in parallel. If I keep going for longer run times by paralleling more I’m wondering if the amps will reach a critical level??? So far no problems but I’m scared to go too much farther at this point until I meet a mathematical genius. I’m trying to make this a solar generator that will run a 100W whatever for about 30 minutes. Once I get the solar panel & charge controller connected the cap packs will be running even less voltage as I doubt the charge controller will charge much over 13 volts. So what do u guys think? Am I making a bomb or a solar generator? Help smile

On May 12, 2013 at 6:38am
Carl wrote:

SlithernSnake,
Your problem is not current related but voltage. A 2.5V, 2,600 Farad Maxwell S-CAP will hold a maximum of 800 Amps of current. That is 8125 joules or 2.26 Watt Hours. Supercapacitors are designed for high current in short burst, mostly used in regenerative breaking and other applications that require high current for short durations.Supercapacitors are not intended to replace batteries. However, as research continues, they will replace batteries, but not in the next few weeks, so to speak. The problem with S-CAPS is voltage drop. The voltage drops in a linear fashion. the greater the load, the faster the voltage drops. That is the problem you are encountering. You can overcome this to a good degree by employing a DC-DC converter. Study Maxwell application notes on these devices, and be very careful! You are dealing with dangerous high levels of current!! I hope this helps you a little.

On May 20, 2013 at 8:05pm
apple wrote:

Look this article. It seems what this article (which is way before that teenage) has nothing to do with super-capacitor.

http://hothardware.com/News/California-Teens-Supercapacitor-Invention-Could-Charge-Cell-Phones-In-20-Seconds/

On May 21, 2013 at 10:21am
Wuzzy wrote:

I have a 60V string of parallel ultra caps. i calculated the total capacitance to be approximately 375 farads. I would like to know how to calculate how long it would take to drop to 26V at a draw of 30 amps. my end result is to find the maximum amperage draw for this voltage change to take effect over a period of one hour, could you please point me in the right direction?

SlithernSnake: I Highly recommend you do at least add resistor balancing, i monitored a 12v string for about 6 months and gradually the 4th in string became higher voltage untill voltage limit reached . (string was solar charged for lights)

On May 31, 2013 at 7:38am
Carl wrote:

Wuzzy,
It can not be calculated because you did not include the total ESR value.
You have a total of 675,000 Joules. That is equivalent to 187.5 Watt Hours. Your load is 1,800 Watts. Do you see the problem?
Here is another way of looking at it: You have 22,500 Coulombs, that is equivalent to 6.25 Ampere Hours. The load you are placing across the S-Cap bank is 30 Amperes. You will not get 30 minutes of run-time. You will be lucky to get a couple of seconds.  The calculations above are based on a 60V string of parallel ultra caps @ 375 Farads. I strongly suggest you go to Maxwell`s web site and study application notes that Maxwell has generously provided for us.
Unfortunately, I am unable to help you further.
Oh, one other thing: It is not recommended to use resistors for balancing due to the load place on the caps. A more effective way is to use Integrated circuits designed for balancing.
When current is drawn from a supercapacitor, there is an instantaneous voltage drop = ILOAD x ESR. Hence ESR limits the amount of current that can be usefully drawn from the supercapacitor.
The maximum power transfer occurs when the load resistance = source resistance = ESR. GOOD LUCK!

On May 31, 2013 at 12:06pm
Carl wrote:

WHY A TEENAGE GIRL`S CELLPHONE BATTERY BREAKTHROUGH MAY NEVER SEE LIGHT AT THE END OF THE TUNNEL.

Solaroad CEO threatens patent suit if 18-year-old California student tries to commercialize her research on supercapacitors.

Eesha Khare, an 18-year-old senior at Lynbrook High School in San Jose, Calif., won both the first prize at the Intel Science Fair and the Project of the Year award for the senior division of the California State Science Fair with her research on supercapacitors.
However, her work has also attracted the attention of the company that holds a patent involving similar technology, and its CEO says he may be forced to bring legal action against her if she tries to commercialize it.  Continue reading here: http://www.networkworld.com/news/2013/052913-battery-breakthrough-270237.html

On June 2, 2013 at 8:16am
Carl wrote:

HEMP DERIVED NANOSHEETS MAY REPLACE GRAPHENE USED IN SUPERCAPACITORS

According to David Mitlin, University of Alberta Chemical Engineer- Cannibas sativa, Indeed marijuana has been found, yet again, to offer a benefit to society. Scientists at the University of Alberta have been working with the waste by products from industrial hemp production facilities to produce a material that has a higher power density than activated carbon.

Apparently when Hemp bast a waste product of hemp production is processed correctly, it can be used to produce nanosheets, thin porous sheets that provide an ideal pathway for electrical charges to move in and out of. The nanosheets are important to the charging and discharging of supercapacitors.

You can read the entire article here at Chemical and Engineerign News : cen.acs.org/articles/91/web/2013/05/Energy-Storing-Nanomaterial-Made-Hemp.html

 

On July 9, 2013 at 7:23pm
franklin wrote:

this is grate .when it advances it will make a revalotanary chnge in science

On July 27, 2013 at 10:41am
SlithernSnake wrote:

Hey guys I’m back with an update on my solar generator. I now have 96 maxwell caps linked in the format I described above with 4 120w solar panels & a 30A digital charge controller feeding them. I can run my 19” LCD TV for a solid hour in the dark & all day with the solar power coming in. I had to get a 2500w pure sine inverter cause the 1500w one I had wasn’t enough to start my 5200 BTU air conditioner. This system will only run it for about 10 minutes but I’m still in the process of adding more solar panels. I have all this installed in my van with the A/C unit in the back window & the solar panels on the roof. I’ve got the caps connected through a switch to the van battery so when the hour of power is up I can start the van, flip the switch & charge the caps back up to 14 volts with the alternator. I’m pretty happy with this system so far & am still adding on to make it better.

On July 30, 2013 at 1:38pm
SlithernSnake wrote:

I guess I need to clarify my statement on the air conditioner, it will run about 10 minutes in the dark without the van battery connected to the caps. In full sun it will run all day after I get a few more panels connected because the 4 120’s just aren’t enough to keep up with the A/C if it has to run nonstop. I’m working on getting it insulated now so the A/C won’t have to work so hard. In full sun the van heats up pretty fast.

On August 11, 2013 at 6:12am
Tester wrote:

A supercap will last up to a century, when staying below 2.2V. So a hundred years no waste. What is better lower cost per watt and every five years a new battery or higher cost per watt and up to a century no waste?

On August 23, 2013 at 10:55am
Jay wrote:

Are there possibilities for the use of SuperCaps in conjunction with solar panels for “solar powered electric vehicles?”  I seem to recall many years ago, talk of solar powered vechicles was all the rage but of course, technology has not allowed us to power them very well using just the sun or keeping them powered when the sun goes down.

Given that Supercapacitors charge so quickly, I wonder what advances (if any) are being made in bring back solar as a charging or powering method for EVs in conjunction with supercaps.

??
J

On October 2, 2013 at 1:33pm
WB wrote:

@Jay

Actually, where I work we use super caps, 2 to 3 in series, and solar panels together to power a micro-controller, some sensors, and a RF transmitter.

I think it is the output current from solar cells that is limiting more advanced solar devices like transportation. When we are able make better solar cells, and probably better super caps, I imagine there will be something along those lines not too far off.

On October 6, 2013 at 10:55pm
Parvathy wrote:

Am working on supercapacitors., MnO2 is my material. Can someone suggest for an organic electrolyte best for this material? i look for a voltage range of 3-4V

On February 5, 2014 at 6:49am
soliman s riogelon wrote:

k

On March 19, 2014 at 8:01am
David Wallenus wrote:

Ultimo lithium ion capacitors applied for regenerative braking in a hybrid bus.
http://www.youtube.com/watch?v=ecslHC53sYk

I see lithium ion capacitors (LICs) are not yet included in this overview of technologies. I feel this is a shame as we are way past R&D level for this technology. Many commercial applications prove Ultimo’s usefulness.

The Ultimo capacitor is a hybrid device with up to three times the energy density of regular EDLCs. Similar or even improved life time and power remain.

On March 19, 2014 at 8:26am
Carl wrote:

Very interesting David! Thanks for posting this! I will study lithium
caps in more detail!

On March 24, 2014 at 11:22pm
ALOK Kumar Gupta wrote:

One who wants information regarding super capacitor, please contact me:
alok@saisoncomponents.com

On April 14, 2014 at 8:06am
Pedro wrote:

@Carl

Do you have a website of your own where you describe your projects in details ?

I currently have no skill in this field but I’d love to acquire some. For example I’d like to revive my Bosch cordless screwdriver with supercaps.

The comments here are already very interesting but having more info would really be great smile

On April 25, 2014 at 1:42pm
Samual wrote:

Hello guys , 
I need your help , i have sun tracking system and boost circuit ,
So i have to charge 26 volt and 4 amp , i am trying 10 super capacitor in series
I need your help to know how to charge the super capacitors
Thanks,

On April 25, 2014 at 8:36pm
Mishra wrote:

Hi Samual

you need to charge through Solar or electricity? Remember super capacitor will behave short circuit in initial stage. So if from solar than no problem but you should have voltage regulator such as LM317. Solar panel should be in series, can use 50 watt 2 nos.

On April 29, 2014 at 2:49pm
qasim ali wrote:

i am working on this i.e power sharing btween battery n supercapacitor…mail me for furthur details qasimaliskt@yahoo.com…thnx

On July 15, 2014 at 8:35am
PeteTy wrote:

Advantages
you dont list efficiency
the capacitors are about 97% efficient (IR droop fast charge)
batteries at best 80%

not sure i understand this LIMITATIONS
“Linear discharge voltage prevents using the full energy spectrum”
sounds like the difference between biPolar and fet transistors

most any electronic stuff that’s line connected nowdays runs from 300VDC stored in capacitors since mains are 50/60 cycles 90-240AC
kind of dont even notice droops and spikes
and ferrite transformers and hollow wire is a lot cheaper and lighter

most new computers run from 12Vdc to supply the .9v at 150A or so
hard to say if the storage is in the coil or capacitor or coil though

 

On July 17, 2014 at 8:25am
Steve Clayton wrote:

Has anyone worked with a capacitor and a reed switch? Looking to transfer the energy without a physical contact.

On August 11, 2014 at 3:03pm
Farriday wrote:

To Carl, 
RE: Capacitor equations.

If the supper cap works just like a capacitor then what you have is a circuit where a capacitor is hooked up to a load.  I have no reason why it would not be that way.

Googling capacitor discharge equations because I did not want to do the math from start with out paper and pencil. 

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capdis.html

Vc=V0 * exp(-t/RC)  is in red color second frame.

Vc is a function of time and V0 is the voltage it was charged to at the initial time.

So, here is how to get the time.  It is and algebraic equation and can be solved for time.  Well what is the minimum voltage the load will fuction at?

ln(Vc/V0)=-t/RC
-R*C*ln(Vc/V0)=t

So, fliping it arround and putting Vmin for Vc we get…

t=-R*C*ln(Vmin/V0)

One can plot this equation and lable the axes.