What is a supercapacitor and how to choose the right one

In energy storage products , super capacitors (Farad capacitors) with energy storage characteristics such as super power , super current , super wide working range, super safety, super long life, etc. are used alone, and the combined use with other energy storage products has become mainstream. . For users, it is very important to choose a suitable supercapacitor.

 1. Characteristics of super capacitors

A supercapacitor is first and foremost a capacitor, and it is unprecedented for a capacitor to reach the Farad level. The word "super" means that compared with ordinary capacitors, it has a super large electric energy storage capacity, while at the same time it retains super power characteristics. This provides opportunities for certain applications - fast charge and fast discharge, fast charge and slow discharge (long discharge time), slow charge and fast discharge.

Supercapacitors also offer some other unique energy storage advantages:

Environment: The working temperature of the supercapacitor is -40℃~70℃, which basically meets most environmental requirements;

Safety: No explosion due to acupuncture, extrusion, vibration, impact, burning, etc.;

Life: charge and discharge can reach more than 1 million cycles, generally more than 10 years is not a problem.

2. Which scenarios will be applied to supercapacitors ?

       If you need a device with high power characteristics and a certain amount of energy to drive electrical appliances, long-term maintenance-free, and use in a wide temperature range, especially when the safety requirements are relatively strict at minus 30 to 40 degrees, it is time to choose A suitable supercapacitor.

       Instantaneous high power, such as a drone ejection device; short-term current supply, such as a police flashlight; such as a braking energy recovery device; diesel vehicle starting in extreme cold weather or battery failure;

 Backup power supply for wind power generation, solar thermal power generation, nuclear power and other power generation terminals; various long-life, high reliability, maintenance-free, high power density backup power supplies;

3. Information you should know before choosing a supercapacitor

So what kind of supercapacitor can meet your needs? What are the crucial parameters of supercapacitors? Its main parameters are voltage (V), capacity (F) and rated current (A).

The power requirements, discharge time and system voltage changes in the specific application of supercapacitors play a decisive role in device selection. In simple terms, two types of parameters must be specified: 1) Operating voltage range; 2) Power output value or how long the current output lasts.

4. How to calculate the required supercapacitor capacity

(1) Constant current, that is, when the current and duration in the supercapacitor condition are constant:

C=It/( Vwork -Vmin)

For example: working starting voltage Vwork=5V; working cut-off voltage Vmin=4.2V; working time t=10s; working power supply I=100mA=0.1A The required capacitance is:

C =0.1*10/(5 -4.2)=1.25F

In this case, you can choose a product with a capacity of 5.5V1.5F.

(2) Constant power, that is, when the power output value is constant

C*ΔU2/2=PT

For example, continuous discharge under 200KW power for 10 seconds, the working voltage range is 450V-750V, the required capacitance capacity:

C=220kw10/(7502-4502)=11F

Therefore, a capacitor (energy storage system) with a capacity of 11F above 750V can meet this demand.

If the calculated capacitance is not within the range of a single unit, multiple supercapacitors can be connected in series and parallel to form a module to meet the specific needs of customers.

Multi-capacitor parallel calculation formula: C=C1+C2+C3+…+Cn

Multi-capacitor series calculation formula: 1/C=1/C1+1/C2+…+1/Cn

5. Suggestions for other product selections

(1) High-voltage series products have advantages in most cases

2.85V and 3.0V products launched by many companies, what are the advantages of high-voltage products?

The life index (1,000,000 cycle life) remains unchanged, and the specific power and specific energy increase under the same volume.

Under the condition of constant power and energy, the number of monomers is reduced, the overall system weight is reduced, and the system optimization design is realized.

(2) To meet special needs

In case of special application requirements, the simple voltage value reference is not meaningful. For example, high temperature above 65℃, 2.5V series products are a good choice. It should be noted that, like all electrochemical components, the ambient temperature will greatly affect the life of the supercapacitor, and the life will be doubled for every 10°C decrease in the high temperature environment.