What is the difference between series and parallel connection of 18650 lithium batteries

　　1、 Series connection of 18650 lithium batteries

　　By connecting multiple 18650 lithium batteries in series, the voltage value of the number of combined batteries can be obtained, but the current remains unchanged. The principle of series connection of lithium batteries is that as the voltage increases, the current remains unchanged. The high voltage caused by battery series connection also has some serious problems. If the 18650 lithium battery pack works in series, when one of the 18650 lithium batteries fails, it will affect the voltage drop of the entire battery pack, shorten the use time sharply, and the faulty 18650 lithium battery has a large internal resistance. If it still works forcibly at this time, it will cause a significant decrease in the output voltage of the entire battery pack. The basic parameter requirements for a series battery are not too high, but the consistency of the battery is still better. The main reason is that there is a decay process in the use of the battery. Inconsistent parameters can cause the decay rate of a certain battery section to accelerate, and if one section of the series circuit is damaged, the entire battery will be scrapped. However, fortunately, this effect is not very strong and the impact is not significant. As long as different types and capacities of batteries are not connected in series, It's basically no big deal.

　　2、 18650 lithium batteries in parallel

　　By combining multiple 18650 lithium batteries in parallel, you can obtain a larger battery capacity, which is more professional. Parallel connection of lithium batteries results in constant voltage and increased capacity. How many lithium batteries are connected in parallel, and the total capacity is the sum of the capacities of all individual lithium batteries.

　　3、 18650 lithium battery series parallel combination

　　The series parallel combination method is to first connect several sets of lithium battery packs that have been connected in series, and then connect them in parallel. This not only increases the output voltage of the battery pack, but also greatly increases the capacity of the 18650 lithium battery pack, just like the lithium battery used in transportation electric bicycles. This clock combination method is used to form a high voltage and high capacity of 36V/20Ah. A single 18650 lithium battery is generally 3.7V, and to achieve a high voltage of 36V, 10 sets of series connected batteries are required.

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