Lithium battery manufacturers tell you the difference between parallel and series batteries. The series or parallel connection of batteries, resistors, capacitors and other electrical components should conform to Ohm's law, series formula and parallel formula. The main difference between parallel and series batteries is the difference in voltage and capacity.
Lithium battery manufacturers tell you the difference between parallel and series batteries
Parallel connection: several batteries, positive and positive, negative and negative, are connected side by side, with constant voltage, increased capacity and corresponding current.
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 does not change.
For example, if you have two 1.5V, 2000mA batteries in series, you will get a 3V, 2000mA battery in series, and a 1.5V, 4000ma battery in parallel.
The supply current can be increased when the parallel voltage of battery is constant; The series connection of batteries can increase the supply voltage without changing the current.
In parallel, in order to get more power, two or more batteries can be connected in parallel. In addition to connecting the batteries in parallel, another way is to use larger batteries. Due to the limitation of the available batteries, this method is not applicable in all cases.
In addition, the large size of the battery is not suitable for the special battery. Most of the chemical batteries can be used in parallel, and lithium-ion batteries are most suitable for parallel use. The battery pack composed of four batteries in parallel keeps the voltage at 1.2V, while the current and running time are quadrupled.
In series, the portable device that needs high power is usually powered by two or more batteries connected in series. If high voltage batteries are used, the size of conductors and switches can be very small.
1、Advantages and disadvantages of battery charging and discharging in series and parallel
1. Advantages of battery parallel discharge: let each battery discharge, balanced, good! There is no defect. The defect is the imbalance or other problems inside the battery.
2. Disadvantages of battery series discharge: battery series discharge, the discharge time is limited by the minimum capacity, easy to cause large capacity of electricity is not released, small capacity of over discharge;
3. New battery series discharge is no problem, old battery, especially the battery with large capacity difference series discharge is not suitable!
Advantages and disadvantages of battery charging and discharging in series and parallel
1. The disadvantages of battery parallel constant current charging are: it is easy to cause bias current - single heating - thermal runaway - other heating - thermal runaway one by one;
2. Advantages of battery parallel constant voltage charging: the battery is not easy to overcharge, easy to balance with voltage;
3. Advantages of battery series charging: let each battery charge the same amount of electricity;
4. Disadvantages of battery series charging: not easy to balance;
5. The new battery with good balance performance is suitable for series charging;
6. Old batteries or batteries with poor consistency are suitable for parallel constant voltage charging.
Small conclusion: battery series discharge is better than battery parallel discharge. It is better to discharge the new battery in series, but it is better to discharge the old battery or the battery with poor consistency in parallel.
The above is the difference between parallel and series batteries. Do not mix different brands of lithium batteries, different capacity or new and old lithium batteries, choose the same performance batteries. When the battery is low, replace all batteries. When lithium batteries are used in series, the same type of batteries should be used.
In short, the purpose of paralleling lithium batteries is to increase capacity. Therefore, parallel charging of lithium batteries also has different design features compared with single-cell lithium batteries, which is mainly reflected in the consistency of charging current design and parallel batteries.
The characteristics of parallel lithium batteries are: the voltage remains the same, 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 effect of parallel current. According to the parallel theory, the current of the main circuit is equal to the sum of the currents of the branches. Therefore, n parallel lithium batteries that have been combined into a battery pack must achieve the same charging efficiency as a single battery, and the charging current should be the sum of n lithium battery currents. , Under the formula of Ohm’s law: I=U/R, this design is reasonable. However, the internal resistance of the batteries in parallel will also change. According to the parallel internal resistance formula, the total internal resistance of two parallel lithium batteries is equal to the ratio of the product of the internal resistance of the two batteries and the sum of the internal resistance. The number of parallel batteries increases and decreases. Therefore, the efficiency of parallel charging of Puxun lithium batteries can be achieved on the basis that the current is less than the sum of the currents of n parallel lithium batteries.
Pay attention to the consistency of the battery in parallel connection of lithium batteries, because the parallel connection of lithium batteries with poor consistency will fail to charge or overcharge during the charging process, which will damage the battery structure and affect the life of the entire battery. Therefore, it is necessary to avoid mixing lithium batteries of different brands, different capacities, and different degrees of new and old when choosing batteries in parallel. The internal requirements for battery consistency are: lithium battery cell voltage difference ≤10mV, internal resistance difference ≤5mΩ, and capacity difference ≤20mA.
In fact, after lithium batteries are connected in parallel, there will be a charging protection chip to protect the lithium batteries. Pu Xun lithium battery manufacturers have fully considered the changing characteristics of lithium batteries after paralleling when making parallel lithium batteries, and the current is also carried out in accordance with the above requirements. The design and battery cell selection, therefore, users need to charge step by step according to the instructions of parallel lithium batteries to avoid possible damage to the battery caused by incorrect charging.
After the batteries are connected in series, the voltages are added together, and the currents are equal, which increases the voltage; the batteries are connected in parallel and the voltage remains the same (provided 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 There is also danger), the current is equal to the sum of the batteries, which can often be regarded as increasing the battery capacity and can provide more current.
The difference between battery series and parallel:
It means that the battery is connected end to end. That is, the positive electrode of the first battery is connected to the negative electrode of the second battery, the positive electrode of the second battery is connected to the negative electrode of the third battery, and so on; the series voltage is equal to the sum of the battery voltages, and the current is equal to the current flowing through each battery; Damage to a section of the battery pack will cause the entire battery pack to be unusable or the voltage drop; the series connection can increase the total voltage.
Refers to the battery's first-to-first connection and end-to-end connection. 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 voltage of a single battery, and the current is equal 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.
Regardless of whether it is connected in series or in parallel, the output power of the battery pack increases.