What affects lithium battery discharge current

What does discharge current mean

The current flowing through the circuit in the discharge process is called the discharge current. For instance, the 1C rate means the entire battery will discharge within one hour, so if a battery has 100 Amp-hrs of capacity with 1C discharge rate, it will have 100 Amps discharge current.

What is the normal discharge current

Different specifications of the battery, the discharge current is different, but should not exceed its maximum discharge current. As mentioned earlier, the discharge current of a Li-ion battery is calculated based on its discharge rate and capacity.

Generally, the discharge rate of lithium-ion batteries is recommended to be between 0.2C and 1C. Therefore, for a 100ah lithium battery, the discharge current is preferably between 20a-100a. Beyond this value, the current should be exceeded, which can be damaging to the battery.

How to calculate the discharge current

If you want to find out how to calculate the discharge current, there are specific parameters you need to know. The most common practice is to express the battery’s capacity as a function of time (the time of complete discharging of the battery). Battery capacity is represented by Cx, where x is the time taken to discharge the battery. For instance, if C10= Z, the time is 10 hours to discharge, and z should be the capacity after discharge.

In the case of discharge current, the discharge rate is equivalent to the battery capacity measured in Ah, which is divided by the time in hours to discharge the battery.  For instance, if the battery’s capacity is 500 Ah with a discharge time of 20 hours, then the discharge rate is given by 500 Ah/20 horse = 25 A discharge current, so the formula is (Cd=I Id) to calculate the discharge current.

Current change during li-ion battery discharge

There are variations in current during li-ion battery discharges. During the discharge of a lithium-ion battery, lithium ions move from the negative electrode to the positive electrode, thereby forming a circuit and current. Lithium battery discharge mode is generally continuous constant current discharge.

The battery specification also includes the maximum discharge current. If the discharge exceeds the maximum discharge current, the battery cell or BMS will be damaged, or the battery overcurrent protection will be triggered and the battery will have no output. But when plugged into the device, the entire cycle is reversed, and lithium ions are released by method and deposited on the anode, which causes the current to change in the battery.

Is discharge current negative or positive

Discharge current can be negative or positive depending on the flow of electrons. For instance, when the capacitor is charging the current directly from the negative plate to the positive plate as the positive charge is deposited on the plate. But if the capacitor discharges, current flows from the positive to the negative plate, and deposition occurs on the negative terminal. It depends on the situation of the charging and discharging rate, which makes the current act positive or negative.

What factors affect the battery discharge current

Multiple factors affect the battery discharge current, some of them are briefly success below:

Electric resistance

When the voltage is constant, the magnitude of the current is inversely proportional to the magnitude of the resistance. In general, lithium-ion batteries have lower electrical resistance than other types of batteries.

Effect of temperature

Another factor affecting the battery discharge current is the temperature. Temperature is vital in battery shell life, charging and voltage control, and overall performance. It is noticeable with an increase in temperature and more chemical directions. The average temperature is  65-90 F for storing the battery.

Voltage

Under the premise of a certain GWh of the battery pack, the higher the voltage of the battery, the smaller the capacity, so the current of the battery is also smaller. Generally speaking, the greater the discharge current of the battery, the greater the risk of the battery pack overheating or short circuiting. Therefore, in large-scale battery packs, people tend to choose high voltage battery specifications, so that the battery current can be controlled within a certain range.

Discharge rate

Under the premise of a certain battery capacity, the higher the discharge rate of the battery, the greater the discharge current. Some specific application scenarios have relatively high requirements on the discharge rate of batteries, such as power batteries, so their discharge currents are generally large.

The effect of discharge current on the battery

Discharge current affects the battery capacity. The larger the discharge current, the faster the battery SOC will drop. This is because the reaction doesn’t have enough time to move to its respective position.

What happens when the discharge current increase

When the discharge current is enhanced, it affects the battery overheat, causing severe damage. Excessive current is usually defined as the maximum current at which the battery can completely discharge over the current limit set by the manufacturers to prevent excessively or any damage to the battery and is mandatory to avoid excessive and continuous supply of current.

Conclusion

Discharge current is defined as the current being discharged by the battery, but sometimes the selection of the discharge current will affect the performance of the battery to a certain extent; therefore, the above content listed all the necessary factors and guides.