May , 2020
Different types of batteries have different internal resistances. For the same type of battery, due to the inconsistent internal chemical characteristics, the internal resistance is also different. The internal resistance of the battery is very small, we generally use milliohm units to mean it. Internal resistance is an important technical indicator to measure battery performance. Under normal circumstances, a battery with a small internal resistance has a strong high-current discharge capability, and a battery with a large internal resistance has a weak discharge capability. In terms of the schematic diagram of the discharge circuit, we can dissect the battery and the internal resistance and divide it into a power supply with no internal resistance connected in series with a small resistance......
The overwhelming majority of 18650 lithium batteries are encapsulated in steel shells. Due to the lack of protection, over-charged batteries will suddenly increase their internal pressure and explode when they exceed the withstand value. Short circuit, excessive temperature or squeezing or even puncturing the battery may cause the battery to explode.
Parallel connection: Several batteries, the positive electrode and the positive electrode, the negative electrode and the negative electrode are connected together side by side, the voltage remains unchanged, the capacity increases, and the corresponding current also increases.
Serial connection: Several batteries are connected in series, that is, the positive electrode and the negative electrode. The negative electrode of the first battery is connected to the positive electrode of the second battery, and so on. The voltage increases, the capacity does not change.
Generally, a 3.7V lithium battery needs an overcharge and overdischarge protection circuit board. If the battery does not have a protection board, it can only be charged with a voltage of about 4.2V, because the ideal full charge voltage of the lithium battery is 4.2V, and the voltage may be damaged if it exceeds 4.2V. The battery is charged by this method and the battery status needs to be monitored at all times.
Why does the lithium ion battery capacity loss? Can the power loss of the lithium ion battery be repaired?
Lithium-ion batteries are the driving force of electronic products. If the battery consumption of electronic products is too large, the battery life of electronic products will be greatly reduced. Many users complain that the battery life of their electronic products is too short. If they are used for a long time, the battery life of the lithium-ion batteries of electronic products will be relatively weakened. The common problem of lithium-ion batteries in daily use is power loss. The more exhausted, the greater the battery loss.
The impact of high temperature on lithium-ion batteries, is high temperature the cause of bulging lithium-ion batteries?
Among all environmental factors, temperature has the greatest influence on the battery's charge and discharge performance. The electrochemical reaction at the electrode / electrolyte interface is related to the ambient temperature. The temperature rise means that the output power of the lithium ion battery will rise. The temperature also affects the transfer speed of the electrolyte. The temperature rises faster, the transfer temperature decreases, and the transfer slows down. The battery charge and discharge performance will also be affected. However, if the temperature is too high above 45 ° C, the chemical balance in the battery will be destroyed, causing side reactions.
The following uses a lithium ion battery with a standard voltage of 4.2V as an example
If the voltage is 4.2V after full charge, it is ok. If the battery time is more than 0.7 times of the new battery, it means the battery is not bad. If the volume voltage is higher than 4.2V after full charge, it means that the charger has problems. (Note The voltmeter must be accurate). Please see the introduction below.