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How to control Farad capacitor discharge time?


Controlling the discharge of supercapacitors:

The resistance of the supercapacitor hinders its rapid discharge. The time constant τ of the supercapacitor is 1~2s. It takes about 5τ to completely discharge the resistance-capacitor circuit, that is to say, if the short-circuit discharge takes about 5~10s (because of the special structure of the electrodes, they are It can actually take hours to get rid of the residual charge completely).

Discharge control time:

Supercapacitors can be charged and discharged rapidly, peak current is only limited by their internal resistance, and even a short circuit is not fatal. In fact, it depends on the size of the capacitor cell. Regarding the matching load, the small cell can put 10A, and the large cell can put 1000A. Another discharge rate constraint is heat. Repeatedly discharging at a severe rate will increase the capacitor temperature, which can lead to an open circuit.

Use caution

Farad capacitors have a fixed polarity. Polarity should be confirmed before use.


Should be used at nominal voltage. When the capacitor voltage exceeds the nominal voltage, the electrolyte will be decomposed, the capacitor will heat up, the capacity will decrease, and the internal resistance will increase, the life span will be shortened, and in some cases, the capacitor function will collapse.

After installing the Farad capacitor, do not forcibly skew or twist the capacitor. Otherwise, the capacitor leads will become loose, resulting in functional deterioration.

After the supercapacitor manufacturer passes the welding of the capacitor, the circuit board and the capacitor need to be cleaned. Because some impurities may cause a short circuit in the capacitor.

Do not place in places with relative humidity greater than 85% or containing toxic gases. Under these circumstances, the lead wire and capacitor case will corrode, resulting in an open circuit.

Can not be placed in high temperature, high humidity environment. It should be stored in an environment with a temperature of -30+50°C and a relative humidity of less than 60% to avoid sudden temperature rise and drop, otherwise it will cause damage.

When used on double-sided circuit boards, the connections are not accessible through capacitors. Because of the installation method of the supercapacitor, it will lead to a short circuit phenomenon.


When soldering the capacitor on the circuit board, do not touch the capacitor case to the circuit board. Otherwise, the solder will penetrate into the capacitor wire hole and affect the function of the capacitor.

Use capacitors in series. Due to technological reasons, the rated operating voltage of unipolar supercapacitors is generally around 2.8V, so it must be used in series in most cases, because it is difficult to ensure that the capacity of each cell in the series circuit is exactly the same, and it is difficult to ensure that the leakage of each cell is also The same, this will lead to different charging voltages of each cell in the series circuit, which may cause capacitor overvoltage damage. Therefore, supercapacitors must be connected in series with a voltage equalizing circuit. When the supercapacitors are used in series, there is a problem of voltage balance between the cells. A simple series connection will lead to overvoltage of one or several cell capacitors, and then damage these capacitors, and the overall function will be affected. Therefore, when the capacitors are used in series , need to get the technical support of the manufacturer.

The external ambient temperature has a significant impact on the service life. The supercapacitor module should be kept away from heat sources as much as possible.

Voltage drop when used as a backup power supply. Because the supercapacitor has the characteristics of large internal resistance, there is a voltage drop ΔV=IR at the moment of discharge.




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Contact: Manager Yang

Mobile: 19851325878



Address: 6th Floor, Building 2, Jingcheng Science and Technology Park, No. 933, Yonghe Road, Chongchuan District, Nantong City