What are the technical parameters of batteries?

A, electromotive force

Electromotive force is defined as the difference between the balance of the two electrode electrode potential, in order to lead acid accumulator The battery For example, E = Ф + 0 - Ф - 0 + RT/F * In (alpha - H2SO4 / alpha H2O).

Among them: E - electromotive force

Ф + 0 - the positive standard electrode potential, its value is 1.690

Ф - 0 - negative standard electrode potential, its value is 0.356

R - universal gas constant, the value of 8.314

T - temperature, and the battery temperature

F - Faraday constant, its value is 96500

Alpha - H2SO4 - activity of sulfuric acid and sulfuric acid concentration

Alpha H2O, water activity, related to the concentration of sulfuric acid

As you can see in the type, the standard of lead-acid battery electromotive force is 1.690 (- 0.0.356) = 2.046 V, so the nominal battery voltage is 2 V.Lead-acid battery electromotive force is related to temperature and the concentration of sulfuric acid.

Second, the rated capacity

In the conditions stipulated in the design (such as temperature, discharge rate and termination voltage, etc.), the battery should be able to release the lowest capacity, unit for ampere hour, expressed as a symbol of C. Capacity is strongly influenced by the discharge rate, so often in the letter "C" in Arabic numerals indicate the discharge rate of the lower right corner, such as C20 = 50, indicates that under 20 when rate has a capacity of 50 Ann hours. Theoretical capacity of the battery can be according to the amount of battery electrode active material in the reactive and calculated on Faraday's law of the active material of electrochemical equivalent calculated accurately. Due to side effects may occur in the battery and the special needs of design, the actual capacity is often lower than the theoretical capacity of the battery.

Third, the rated voltage

Typical working voltage of battery at room temperature, also called nominal voltage. It is reference when choosing different types of batteries. Actual working voltage vary with different conditions of use. Open circuit voltage of battery is equal to the balance of positive and negative electrode electrode potential difference. It is only related to the types of electrode active material, and has nothing to do with the number of active substances. Battery voltage is essentially a dc voltage, but in some special conditions, the electrode reaction caused by metal crystals or some into phase membrane phase transformation can cause tiny fluctuation of voltage, this phenomenon is called noise. Width of fluctuation in a small but frequency range is very wide, so it can be distinguished from the noise circuit self-excited.

Fourth, open circuit voltage

Voltage of the battery under open circuit state in referred to as the open circuit voltage. Open circuit voltage of battery is equal to the battery in the circuit (i.e., not an electric current passes through the poles) of the positive electrode potential and the cathode of the battery electrode potential difference. The open circuit voltage of the battery is open, said V open = Ф + V - Ф - namely, including Ф +, Ф - respectively is negative electrode potential of the battery. Open circuit voltage of battery, generally are less than its electromotive force. This is because the battery of the poles of electrode potential in electrolyte solution, usually not equilibrium electrode potential, but the stability of electrode potential. Can approximate commonly believed that the open circuit voltage of battery is electromotive force of the battery.

Five, the internal resistance

Battery internal resistance is the point at which the current through the battery internal resistance. It includes the ohmic resistance and the polarization resistance, polarization resistance and include the electrochemical polarization resistance and the concentration polarization resistance. As a result of the existence of internal resistance, the working voltage of the battery voltage is always less than the electromotive force of battery or open. Battery internal resistance is not constant, changing with time in the process of charging and discharging (larger) gradually, this is because the composition of the active material, electrolyte concentration and temperature are in constant change. Ohm resistance obey ohm's law, the polarization resistance increases with increasing current density, but it is not linear relationship. Used to increase with the increase of current density.

Internal resistance of battery performance is an important index, it directly affects the working voltage of the battery, working current, the output of energy and power, for the battery, its internal resistance as small as possible.

Six, charge and discharge rate

Sometimes rate and the rate of two kinds of representation. Rate is expressed as the charging and discharging rate of charge and discharge time, when the value is equal to the capacity of the battery on the Ann (hours) divided by the provisions of the charge and discharge current (Ann), the number of hours. Ratio is the another representation of charge and discharge rate, the rate of its numerical too bottom. Galvanic battery discharge rate is by a constant resistance discharge to the time of termination voltage. Affect the performance of battery discharge rate is bigger.

Seven, the impedance

Inside the battery has a great deal of electrodes, electrolyte interface area, so the battery can be equivalent to a small resistance, capacitance and inductance in series circuit. But the reality is much more complicated, especially the impedance of the battery and dc level varies with time, and the measured impedance applies only to specific measurement state.

Eight, life

Storage life means starting from the battery is made to use allows for the longest time, between unit for years. Including storage life and the life, total period according to the validity of the battery. The life of the storage battery is wet storage life and dry storage life. Cycle life is under the condition of meet the provisions of the battery can achieve maximum charge and discharge cycles. Within the prescribed circle life must also stipulates that when charging and discharging cycle test system, including charge and discharge rate, depth of discharge and environmental temperature range, etc.

Nine, self-discharge rate

Battery capacity loss rate on its own electricity in the storage process. With self-discharge loss capacity of the storage time of storage capacity before expressed as percentage.

Ten, battery related technical parameters are calculated

E for electromotive force, r for power resistance, within the voltage U = Ir, E = U + U outside inside

Scope of application: pure resistance circuit

Energy conversion in the closed circuit:

E=U+Ir

EI=UI+I^2R

P = EI release

P = the UI

Pure resistance in the circuit

P = I ^ 2 r

=E^2R/(R+r)^2

=E^2/(R^2+2r+r^2/R)

When r = R, P output is the largest and P output is E ^ 2/4r (mean inequality)

The page contains the contents of the machine translation.