Lithium Batteries Knowledge

Many people are elusive about newly-purchased lithium batteries. The author summarized 10 tips on how to use lithium batteries, and share them with you, hoping to help.

The quality of the charger directly determines the length of the life of the lithium-ion battery, so it is very important to choose a good quality charger. The output voltage of the charger must be matched according to your battery.

I believe that most consumers have heard that the life of a lithium battery is "500 times", 500 times of charge and discharge, beyond this number, the battery will "end of life", many friends in order to be able to extend the battery life, every time The battery is charged only when it is completely exhausted. Does this really extend the life of the battery? the answer is negative. The life of a lithium battery is "500 times", which does not refer to the number of times of charging, but a cycle of charging and discharging.

The use of chargers allows many electronic devices to operate normally. Without chargers, our lives will be troubled to a certain extent. In order to enhance everyone's understanding of the charger, this article will introduce the wireless charger related content, mainly to analyze whether the wireless charger is harmful to the mobile phone and explain the precautions of the wireless charger. If you are interested in chargers, you might as well continue reading.

Generally, a 3.7V lithium battery needs to have a "protection circuit board" for overcharging and overdischarging. If the battery does not have a protection circuit board, it can only be charged with a voltage of about 4.2V, because the ideal full charge voltage of a lithium battery is 4.2V. If the voltage is exceed 4.2V, the battery may is damaged, it is necessary to monitor the condition of the battery at the same time when charging with this method.

The main components of lithium-ion batteries include positive electrode, negative electrode, electrolyte, separator, positive electrode lead, negative electrode lead, safety device and battery casing, etc. Most of the materials are combustible materials. The distance between the positive and negative electrodes of a lithium-ion battery is extremely short. Any small defect on the separator between the positive and negative electrodes may form a short circuit, causing local high temperature, and causing the separation of the positive and negative electrodes in nearby locations to decompose and chain The reaction will eventually cause the battery to catch fire or explode.

The nature of the ignition of lithium-ion batteries is that the heat in the battery fails to be released according to the design intent, causing internal and external combustion materials to ignite after ignition. The main reasons for the fire are external short circuit, external high temperature and internal short circuit.

Different types of batteries have different internal resistances. The same type of battery has different internal resistance due to the inconsistency of internal chemical characteristics. The internal resistance of the battery is very small, we generally use the unit of milliohm 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 capacity, and a battery with a large internal resistance has a weak discharge capacity. In terms of the schematic diagram of the discharge circuit, we can consider the battery and the internal resistance separately, and divide it into a power supply with no internal resistance at all and connect it with a small resistance in series. At this time, if the external load is light, then the voltage distributed to this small resistor is small. On the contrary, if the external load is very heavy, then the voltage distributed to this small resistor is relatively large, and part of the power will be consumed in this Internal resistance (may be converted into heating, or some complex reverse electrochemical reaction). The internal resistance of a rechargeable battery when it leaves the factory is relatively small, but after long-term use, due to the exhaustion of the battery’s internal electrolyte and the decrease in the activity of the internal chemical substances in the battery, this internal resistance will gradually increase until the internal resistance is large enough. The power inside the battery cannot be released normally, and the battery is dead at this time. The vast majority of aging batteries are useless due to excessive internal resistance and have to be scrapped. Therefore, we should pay more attention to the discharged capacity of the battery rather than the charged capacity.

At present, major lithium battery manufacturers have designed various types of lithium battery protection chips for different types of lithium-ion battery overcharge, overdischarge, and overcurrent protection requirements to ensure battery safety performance and avoid deterioration of battery characteristics. Most of these lithium battery protection chips are suitable for lithium-ion batteries with 1-4 cells in series, and very few new products, such as Texas Instruments' BQ77PL900 chip, are suitable for lithium-ion batteries with 5-10 cells in series, and their protection functions Perfect and widely used in many lithium battery protection circuits. However, for many serial numbers, such as battery packs with more than 10 strings of lithium batteries in series or the number of protection chips are different from the actual number of lithium battery packs in series, if the current integrated circuit chips on the market are used to make the protection circuit, there will be no The disadvantage of not being flexible enough to achieve protection or use.

Low-temperature lithium-ion batteries are classified according to their discharge performance: energy storage low-temperature lithium-ion batteries, rate-type low-temperature lithium-ion batteries.