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What is 'super capacitor'? Can we replace batteries with super capacitors?

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pradeep_k_b

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Hi,recently i heard about super capacitors,and i think its available up to 500F,its really surprising.can we use this as a energy storage device?.can we replace batteries with this?
 

tpetar

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Exist even over 1000F / cap.


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.

http://www.cellergycap.com/index.php?option=com_content&view=article&id=17&Itemid=3

http://batteryuniversity.com/learn/article/whats_the_role_of_the_supercapacitor


 

tpetar

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tpetar

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tpetar

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Of course my friend.

- - - Updated - - -

This is not manufacturer, they are distributers of components, manufacturers can give better price, but check here:

http://www.tme.eu

Go to Passives/Supercapacitors

- - - Updated - - -

1F 2,5eur
100F 7,2eur
300F 12eur
400F 14eur


There is also ultra cheap 22F 2eur,....

Very important thing is to pay attention on voltage of supercap. Voltage can vary from product to product.

;-)
 
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tpetar

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They make "one" big cell to look like one, but inside are several single caps on lover voltages in serie. Of course this make easy to make bigger supercap system.
 

pradeep_k_b

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But i think super capacitors will discharge quickly than that of batteries....so is it possible to use this as a energy storage device?...and i heard something like its better for vehicles,can i replace my bike's lead acid battery with this super capacitor?
 

Tahmid

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Discharge rate depends on capacitance and load resistance.

You also have to keep in mind that the capacitor will discharge to 0V when completely discharged, and will have low voltages when being discharged (very low after half or more of it is discharged). You don't face this problem when you use lead acid batteries.
 

ninju

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It is due to nano technology. consider a cube of side 'a' units. Its surface area is 6 a^2. Now, cut it into two. Each has a total surface area of 4a^2, for a total area of 8 a ^2.

As you keep dividing into smaller and smaller pieces, the area drastically increases.

Capacitance is directly proportional to area. Hence ,using this principle, very large value capacitors are made. They are used to power automobiles. People are working on powering portable electronics, satellites etc.

Also, you can limit the amount of charge withdrawn at a time from a capacitor, thereby using it as a power source. These caps have the highest energy density. (energy stored per unit mass)

Its not possible to replace lead acid battery with this. Batteries convert chemical energy into electrical energy. This is merely a storage device. You'll have to charge it somewhere. Even though automobile batteries do get recharged to some extent while the automobile is running, it still is a battery and this is not. Also, this is more prone to accidents, as one accidental short can damage almost everything involved.Fun fact: Quite a few automobiles use their chassis as ground. Some use a positive potential and some use a negative potential. (This one was initially done to prevent rusting of the surface).
 

Externet

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A 16 V supercapacitor of 150 Farads could replace an automobile battery from figures I calculated a long ago if I remember well... But they are leaky; self discharge if not topped up often.
 

manishanand14

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can i replace my bike's lead acid battery with this super capacitor?
Since supercapacitor can absorb and release huge bursts of energy due to it's low ESR[equivalent series resistance] , they can be used to make hybrid batteries.

Even if you simply add a proper voltage rating Supercapacitor across your Moterbike battery in parallel, it will significantly improve it's performance, like mitigating the starting problem under low charge state.

You can't replace a bike's battery with a Supercapacitor.
 

tpetar

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If you full charge supercap, tomorrow you will see that cap is empty. He is not direct replacement for battery, bat can do the job in lots of situations very well.

Supercaps can be used in frequent discharging / charging situations, I give example city buses in earlier posts, city cars batteries, bykes,....

When supercap is charged he should be used soon as possible, caps are not good for keeping electricity in the long run.

Supercaps can give high energy for small time, and can give many many charge/discharge cycles.
 

Tahmid

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The energy stored in a 100F capacitor at 12V is (0.5 * 100 * 12 * 12)J = 7200J

The energy stored in a 12V 7.5Ah can be roughly estimated to be around (0.5 (12 + 10) * 7.5 * 3600)J = 297000J

So, you'd need a HUGE super capacitor to store the same amount of energy as the 7.5Ah battery. So, in general, the supercapacitor can not be substituted in place of batteries. In some situations, maybe it can, but it depends on the specific circuit.

In cases where LARGE current surges are required (and also, frequent charge/discharge cycles), you can easily use the super capacitor.

Hope this helps.
Tahmid.
 

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