# How to increase the capacity of the battery? What is the difference between batteries connected in series and parallel?

The purpose of connecting batteries in parallel is to increase capacity. Therefore, charging batteries in parallel has different design characteristics compared with single-cell batteries, mainly reflected in the consistency of the charging current design and parallel batteries.

The characteristics of parallel batteries are: the voltage remains unchanged, the battery capacity is added, the internal resistance is reduced, and the power supply time is extended. The core content of parallel charging is the size and function of the parallel current. According to the theory of parallel connection, the main circuit current is equal to the sum of the branch circuit currents. Therefore, to achieve the same charging efficiency as a single battery for n parallel batteries that have been combined into a battery pack, the charging current should be the sum of n battery currents. Ohm’s law: This design is reasonable under the formula of I=U/R. However, the internal resistance of batteries connected in parallel will also change. According to the parallel internal resistance formula, the total internal resistance of two parallel batteries is equal to the ratio of the product of the internal resistance of the two batteries to the sum of their internal resistances. It decreases as the number of batteries increases. Therefore, the efficiency of battery parallel charging can be realized on the basis that the current is less than the sum of n parallel battery currents.

Pay attention to the consistency of batteries when connecting batteries in parallel, because parallel batteries with poor consistency will fail to charge or overcharge during charging, which will damage the battery structure and affect the life of the entire battery pack. Therefore, when choosing parallel batteries, you should avoid mixing batteries of different brands, different capacities, and different levels of old and new. The internal requirements for battery consistency are battery cell voltage difference ≤ 10mV, internal resistance difference ≤ 5mΩ, and capacity difference ≤ 20mA.

In fact, after the batteries are connected in parallel, there will be a charging protection chip to protect the battery. The battery manufacturer has fully considered the changing characteristics of the batteries after the parallel connection when making the parallel connection and also carried out the current design and battery cell selection according to the above requirements. Therefore, the user needs to charge the battery step by step according to the instructions of the parallel battery to avoid possible damage to the battery caused by incorrect charging.

The voltage of the batteries connected in series is equal to the sum of the voltages of the batteries connected in series. When the voltage is increased, the bulbs are connected in series. One switch can control all the bulbs connected in series in one circuit.

The use of batteries in series can increase the output voltage. What are the characteristics of connecting bulbs in series: the sum of the voltages of each bulb is the total voltage of the circuit

After the batteries are connected in series, the voltages are added, and the currents are equal, which increases the voltage; the batteries are connected in parallel, and the voltage remains unchanged (the premise is that the batteries with the same voltage can be connected in parallel, otherwise the high voltage will charge the low voltage. If the difference is too large, it there may be dangerous), the current is equal to the sum of each battery, which can often be considered as increasing the battery capacity and can provide more current.

As the voltage increases, the capacity remains the same.

## The difference between batteries connected in series and parallel:

### The battery in series:

It means that the batteries are connected end to end. That is, the positive pole of the first battery is connected to the negative pole of the second battery, the positive pole of the second battery is connected to the negative pole of the third battery, and so on;

The series voltage is equal to the sum of the battery voltages, and the current is similar to the current flowing through each battery;

Damage to one section of the battery pack will cause the entire battery pack to be unusable or the voltage to drop;

Connecting them in series can increase the total voltage.

### Batteries connected in parallel:

It means that the battery is connected first and last. That is, the positive poles of all batteries are connected, and the negative poles of all batteries are connected.

The parallel voltage is equal to the individual battery voltage, and the current is similar to the sum of the battery currents.

Although the endurance of the battery pack is enhanced, the damage caused by the short-circuit current is more serious;

## The parallel connection can increase the total current.

1. When the batteries are connected in parallel, the voltage is equal everywhere, that is, Ua=Ub=Uc=Uo; the current is the sum of the currents of each battery, that is, Io=Ia+Ib+Ic.

The parallel connection of batteries is suitable for occasions where the voltage is constant and the current needs to be increased.

1. When the batteries are connected in series, the current is equal everywhere, that is, Io=Ia=Ib=Ic; the voltage is the sum of the voltages of each battery, that is, Uo=Ua+Ub+Uc.

The use of batteries in series is suitable for occasions where the current remains constant and the voltage needs to be increased.

Whether connected in series or in parallel, the output power of the battery pack is increased.

Parallel connection: Several batteries, positive and positive, negative and negative are connected side by side, the voltage remains unchanged, the capacity increases, and the corresponding current also increases. Series connection: Several batteries are connected in series, that is, positive and negative, the negative of the first section is connected to the positive of the second section, and so on. As the voltage increases, the capacity remains the same. That is to say, if they are connected in series, the electromotive force is the sum of the electromotive force of the two batteries. If they are connected in parallel, the voltage they provide to the consumer is only as large as the electromotive force of one battery. Hope my answer can help you! I am also learning this part of knowledge, it is difficult.

## When connected in series, the voltage is the sum of the voltages of the two batteries. When connected in parallel, the voltage is equal to the voltage of these two batteries

Connect in series to increase the voltage, and connect in parallel to increase the capacity. For example, if you have two 1.5V, 2000mAh batteries, you can get a 3V, 2000mAh battery after connecting in series, and a 1.5V, 4000mAh battery after connecting in parallel.

The use of batteries in series is suitable for occasions where the current remains constant and the voltage needs to be increased.

Whether connected in series or in parallel, the output power of the battery pack is increased.

1. In series, the current is constant and the voltage is added; in parallel, the voltage is constant and the current is added
2. Although the voltage has not changed, two 12v batteries are connected in series to obtain a higher voltage to adapt to electrical appliances. If the current is above 100w, a draft of 10A is required. For example, the design value is an inverter with 12v input. The requirements are extremely high, so reducing the current is the main reason, and two parallel connections are required, but the allowable normal discharge current is doubled. If 24v is used, the current is only 5A. Therefore, high-voltage electrical appliances (such as electric vehicles) are used in many places for this reason. But there are also some appliances that are originally 12v. When their power (current) is large, the motor, in order to improve the working time of the battery or the current of a single battery is not enough to drive, the battery is only 12v, and the power of some electrical appliances is relatively large.