Super Cap

Super cap, super capacitor for short. Maxfarad super cap's Application Guidelines

Do not apply a reversed voltage. Reverse polarity is not recommended. If a reversed voltage is applied for a long time, the leakage current will increase abruptly, which may cause a decrease in the capacity, an increase in the internal resistance, and cause electrolyte leakage or damage to the capacitor in some cases.

Do not apply any voltage higher than the operating maximum voltage. Super cap are rated with a nominal recommended working or applied voltage. If an over voltage is applied to the capacitor, the leakage current will increase abruptly and the capacitor will become overheated, which may cause a decrease in the capacity, an increase in the internal resistance, and cause leakage or damage to the capacitor in some cases. But, surge voltage can usually be tolerated by the super cap.

Ripple Current Super caps have a higher internal resistance than aluminum electrolytic capacitors and are more susceptible to internal heat generation when exposed to ripple current, this may cause a decrease in the capacity, an increase in the internal resistance, and cause electrolyte leakage or damage to the capacitor in some cases.

Charging and Discharging. Super cap can be charged using various methods, including constant current, constant power, constant voltage or by paralleling to an energy source, i.e. battery, fuel cell, DC converter, etc. In general, characteristics of constant current and constant resistance discharging are respectively represented by the equation (1) and (2) below:
Discharging time (t) of constant current discharge t = C x (Vo-V1) / l…..(1) Discharging time (t) of constant resistance discharge t = -CRIn(V1/Vo)…..(2) t = discharging time(s) vo = initial voltage (v) v1 = terminal voltage (v) l = current during back-up (A) The maximum recommended charge current, I, for a super cap is calculated as follows: I = Vw / 5R where Vw is the charge voltage and R is the super cap DC ESR

Do not use in a circuit where quick charge and discharge are repeated very often. In a circuit where quick charge and discharge are repeated very often, the capacitor will become overheated, which may cause a decrease in the capacitance, an increase in the internal resistance, and cause electrolyte leakage or damage to the capacitor in some cases. Reduce the charge and discharge currents while selecting a capacitor with low internal resistance, and make sure that the capacitor surface temperature does not rise more than 10°C.

Super cap life depends on the ambient temperature. The lifetime of super cap is seriously affected by change in ambient temperature. If the temperature is lowered by 10°C, the lifetime will be approximately doubled. As a result, it is recommended to use the super cap at the lowest temperature possible to decrease internal degradation and ESR increase. If the capacitor is used at a temperature exceeding its maximum guaranteed temperature, not only is its life shortened, but increased vapor pressure of electrolyte or electrochemical reactions may increase the internal pressure, and cause electrolyte leakage or damage to the capacitor in some cases.

Voltage drop occurs during back-up operation. In applications where the discharge current is large, or a large current flows instantaneously, super cap may not operate at the start of discharge because of the large voltage drop (IR drop) caused by the capacitors internal resistance (ESR). The formula for the voltage drop, Vdrop, during a discharge at I current for t seconds is: Vdrop = I(R + t/C)

Series Connecting of super cap. A series connection can cause an imbalance in the voltage across a super cap causing the capacitors to have an over voltage which can cause electrolyte degradation, excessive gas generation, increased ESR, decrease in capacitance and reduced life. To prevent voltage imbalance, passive or active voltage balancing is recommended. Passive voltage balancing should be performed using divider resistors placed in parallel with the super cap. Using resistance values between100 Ω/F to 470 Ω/F are recommended.

About vibration. A terminal blank, a terminal bend, and a crease may occur by adding too much vibration to a capacitor. When there becomes too much vibration, please contact our company.

When used on a double sided printed circuit board, do not design exposed circuit board traces under the super cap. An electrical short could occur if the super cap electrolyte should leak onto the circuit board.

Do not store in high temperature and high humidity conditions. Avoid high temperature or high humidity or direct rays when storing capacitors. Avoid direct contact with water, salt water or oil, toxic gases, or dusty environment.

When soldering the super cap to the wiring board, do not attach the body of the super cap to the circuit boards. If the body of the capacitor is attached directly to the circuit board, the flux or solder can blow through the mounting holes in the circuit board, possibly causing internal damage to the super cap.

Do not overheat when soldered. Excessive heat may cause deterioration of the electrical characteristics of the aerogel super cap, electrolyte leakage or an increase in internal pressure.

Circuit board cleaning after soldering. Circuit boards can be immersed or ultrasonically cleaned using suitable cleaning solvents for up to 5 minutes and up to 60°C maximum temperatures. The boards should be thoroughly rinsed and dried.

Be careful not to apply an excessive force to the capacitor body, terminals or lead wires. If the capacitor body is subjected to stress such as grabbing, falling, bend, pushing or twisting after mounted, its terminals may come off, leading to open, short or liquid leakage.

Emergency procedures. If a super cap is found to be overheating or starts to smell, immediately switch off the unit’s main power or load to stop operation. Do not expose your face and hands if exposed to electrolyte. Wash exposed area thoroughly with soap and water.