Lithium battery charging method

Lithium rechargeable batteries have been widely used. lithium iron phosphate batteries are also used more often because of their unique advantages. The charger of the lithium iron phosphate battery is different from the ordinary lithium battery. The maximum termination charging voltage of a lithium battery is 4.2 volts; The lithium iron phosphate battery is 3.65 volts(some online, the maximum can not be higher than 3.8 volts). The question is: Can you use the charger of the mobile phone(slightly modified) to charge the lithium iron phosphate battery? Or use the scrapped lithium battery to protect the circuit board(slightly modified) for charging protection of lithium iron phosphate batteries.?

However, the overall voltage has not yet reached the cut-off voltage of charging. If the battery continues to be charged, it will be overcharged. The same is true for discharge. The protection plate is not a single charge, but a protection. If it does not have the balance function, it is the worst protection, and the whole is not actually full. Even with equalizing protection plate, it is false equalizing. Through the bypass resistance, the full battery bypass continues to be filled with other batteries to achieve the overall filling effect. Because the bypass resistance power is limited, generally 100mAh is very large, which is actually a drop in the bucket for the whole battery pack. In fact, the balance of series batteries can be said to be the world's difficult problem, there is no low cost balance of large current, and the larger the series number, the more difficult the balance. In fact, it is because the battery in series is not easy to control due to overcharge and discharge, and the lithium battery is damaged very quickly due to overcharge and discharge, and there are safety problems. The lithium iron phosphate developed just now has a low capacity and low energy, which is inferior to lithium battery in all aspects.

The line is the detection line of the protection board, which does not need thick line. The red and black lines are the power supply lines, and the large current passing through requires thick line. The protection plate is used to detect the voltage of each single cell. It not only protects each cell from discharging, but also protects it from charging. Otherwise, it cannot be discharged or charged through the protection plate, playing a protective role.

When charging, it is the line connected by the balance charging board. Generally, it is directly connected in series from both ends. The voltage of the charger is greater than the voltage of the battery pack. The voltage of each single cell detected by the wiring is equivalent to that of a parallel regulator. The charging voltage of the single cell will not exceed the value of the regulator, while other single batteries continue to be charged through the bypass of the regulator. At this time, the electric quantity of each cell is close to full, so the charging current is small, and each cell is full. The charger can only protect the voltage of the whole battery pack, and the balance charging board is to ensure that each single cell is overcharged and each single cell is full, and cannot stop the charging of the whole battery pack because one cell is full.

1. Some mobile phone chargers are protected by themselves. When it is detected that the lithium battery voltage reaches 4.2v, they will stop charging. My idea is to connect a slightly more powerful silicon diode (positive voltage drop of about 0.6v) between the lithium iron phosphate battery and the charger, so that when the voltage of the lithium iron phosphate battery reaches 3.6v, and the diode voltage drop is exactly 4.2v, it can also be detected by the charger and stop charging.

2, the phone battery protection line, take out, used in the lithium iron phosphate battery charging protection, is also based on the principle of charging in series a diode, played a 4.2v protection.

The life of electricity is generally 300-500 charging cycles. It is assumed that the electric quantity provided by a complete discharge is 1Q. If the reduction of electric quantity after each charging cycle is not taken into account, the lithium battery can provide or supplement 300q-500q electricity in total within its service life. So we know that if you charge 1/2 every time, you can charge 600-1000 times; If you fill it 1/3 at a time, you can fill it 900-1500 times. And so on, if you charge it at random, you don't know how many times. But anyway, no matter how much you charge it, it's going to add up to 300q-500q which is constant. So, we can also understand: lithium battery life is related to the total charge of the battery, and has nothing to do with the number of charges. The effect of deep discharge and shallow discharge on the life of lithium battery is similar. So, some manufacturers say, "so-and-so powerful lithium battery, can charge more than 1500 times. This is pure consumer ignorance.

In fact, shallow discharge and shallow charge are more beneficial to lithium battery. Only when the power module of the product is calibrated for lithium battery can deep discharge and deep charge be necessary. Therefore, the use of lithium electric power supply products do not need to adhere to the process, all in order to facilitate, at any time charging, do not have to worry about the impact of life.

In the use of lithium batteries should be noted that the battery placed for a period of time will enter the dormant state, at this time the capacity is lower than the normal value, the use time is also shortened. But lithium battery is easy to activate, as long as after 3-5 normal charge and discharge cycle can activate the battery, restore the normal capacity. Due to the characteristics of lithium battery itself, it has almost no memory effect. Therefore, users do not need special methods and equipment in the activation process of new lithium batteries. Not only in theory, but in my own practice, the "natural activation" of a standard charge from the start is the best.

For the lithium battery "activation" problem, many people say: charging time must be more than 12 hours, repeated three times, in order to activate the battery. This "the first three charge to charge more than 12 hours", obviously from the nickel battery (such as nickel cadmium and nickel hydrogen) continued to say. So this kind of saying, can say to be misrepresented namely at the beginning. The charge and discharge characteristics of lithium battery and nickel battery are very different, and it can be very clear to tell you that all the serious and formal technical data I have looked up all emphasize that overcharge and overdischarge will cause great harm to lithium battery, especially liquid lithium ion battery. Therefore, it is best to charge according to the standard time and standard method, especially do not charge more than 12 hours.

In addition, lithium batteries or chargers automatically stop charging when the battery is fully charged, and there is no so-called "trickle" of nickel chargers that last for more than 10 hours. In other words, if your lithium battery is fully charged, it will go blank on the charger. And none of us can guarantee that the battery charge-discharge protection circuit characteristics will never change and the quality of foolproof, so your battery will be in danger for a long time to wander around. This is another reason we oppose long - term charging.

In addition, on some machines, if the charger is not removed after charging for a certain period of time, the system will not only not stop charging, but also start the discharging - charging cycle. This may serve a purpose, but it is clearly bad for battery life. At the same time, long charging takes a long time and often takes place at night. In China's power grid, the voltage at night is high and fluctuates greatly in many places. Having said that lithium batteries are delicate, they are much less resistant to fluctuations in charge and discharge than nickel ones, which poses additional risks.

In addition, another aspect that cannot be ignored is that lithium battery is also not suitable for over discharge, over discharge on lithium battery is also very bad. This leads to the following question.

2. When should you start charging in normal use

Since the number of charges and discharges is limited, lithium batteries should be used up and recharged as much as possible. However, I found an experimental table about the charge and discharge cycle of lithium ion battery, and the data about the cycle life are listed as follows:

Cycle life (10%DOD):>1000

Cycle life (100%DOD):>200

DOD stands for discharge depth. As can be seen from the table, charging times are related to discharge depth, and the cycle life of 10%DOD is much longer than that of 100%DOD. , of course, if the conversion to the actual charge relative to the total capacity: * 1000 * 200 = 200 = 100100%, 10% of the latter to fully charge and discharge is still relatively good, but in front of the net friend of the idea to do some correction: under normal circumstances, you should have a reservation, according to the principle of battery remaining power run out to refill charging, but if your batteries in your expected to 2 days can't insist on the whole during the day, it should start charging in a timely manner, of course, if you are willing to carry the charger to the office when BieLun again.

And when you need to recharge in anticipation of an important event that will result in busy communications, even if the battery has a lot of power left, then you just charge it in advance, because you're not really losing "1" charge cycle life, which is "0.

The principle of recharging after a battery has run out of juice is not to take you to extremes. As popular as long charging is, "try to use up your machine's battery, preferably by shutting it down automatically." This is actually done on nickel batteries to avoid memory effects, but unfortunately it's also used on lithium batteries. There have been examples of people who continue to use a machine without charging after warnings that the battery is too low. Results in this example of the machine in the later charge and boot are no response, had to send to customer service maintenance. This is actually caused by the low voltage of the battery due to excessive discharge, so that it does not have the normal conditions for charging and starting up.

3, the correct approach to lithium battery

To sum up, the most important hints for the charging and discharging problems of lithium batteries in use are as follows:

1. Charge according to standard time and procedure, even the first three times;

2, when the machine power is too low, should try to timely start charging;

3. No special method is required for the activation of lithium battery, which will be activated naturally in normal use of the machine. If you insist on using the popular "first three 12-hour long charge and activate" method, it will not actually work.

So all the pursuit of 12 hours of super-long charging and automatic shut-down of lithium batteries is wrong. If you have done something wrong before, please correct it before it is too late.

4. Pay attention to fire prevention when using lithium batteries

Many people may be familiar with lithium batteries from mobile phones. In fact, it is used in many home appliances. There is no doubt that the advantages of lithium batteries such as high efficiency and light weight are rapidly spreading their application. But did you know that even careless use of it can get you in hot water?

Lithium battery has a light weight, high efficiency, the advantages of resistance to low temperature 40 ℃ (-), 0. 3mm thick, stamp size lithium battery can be used for more than 5 years, in recent years is gradually phased out the use of alkaline dry batteries and manganese batteries, widely used in many high-end home appliances and mobile phones.

Unlike the water-soluble electrolytes of zinc chloride and potassium hydroxide in existing manganese and alkaline dry batteries, lithium batteries use organic solvents. The positive electrode of lithium battery is made of manganese dioxide, lead fluoride and sulfurous chloride. The lithium metal foil used in the negative electrode is compared with the zinc chloride used in the negative electrode of the general battery.

However, lithium batteries in the use of the process often appear in the heat, combustion phenomenon, the light affect the use of the host, the heavy will burn down the host cause a fire. It is reported that in recent years, there have been a number of accidents in Japan caused by household fires caused by the hot burning of lithium batteries.

So why do lithium batteries get hot and burn? The original lithium battery in many materials and water contact, can occur violent chemical reactions and release a lot of heat resulting in heating, combustion phenomenon. The manganese dioxide of lithium battery positive pole, dip in a small drop of water to be able to appear calorific phenomenon only. After the chlorinated sulfite in the lithium battery contacts with the water, in the generation of hydrochloric acid and sulfur dioxide at the same time to release heat energy, several factors make the lithium battery into the life of the "fire", so people must pay attention to the use of lithium battery waterproof, moisture-proof. After all kinds of hosts are out of service, the lithium battery should be taken off and placed in dry and low temperature for safekeeping, in order to prevent and avoid the family fire accident caused by improper use of lithium battery.

The page contains the contents of the machine translation.